├── Dockerfile ├── src ├── crypto │ ├── curve │ │ ├── curve_ed25519.h │ │ ├── curve_ristretto.h │ │ ├── curve_ed25519.c │ │ ├── curve_ristretto.c │ │ └── curve.h │ ├── kdf │ │ ├── kdf_naor_reingold.h │ │ ├── kdf_sdhi.h │ │ ├── kdf_default.h │ │ ├── kdf_default.c │ │ ├── kdf.h │ │ ├── kdf_sdhi.c │ │ └── kdf_naor_reingold.c │ ├── voprf │ │ ├── voprf_mul_twohashdh.h │ │ ├── voprf_exp_twohashdh.h │ │ ├── voprf_twohashdh.h │ │ ├── voprf_exp_twohashdh.c │ │ ├── voprf_mul_twohashdh.c │ │ ├── voprf_twohashdh.c │ │ └── voprf.h │ └── dleqproof │ │ ├── dleqproof.h │ │ └── dleqproof.c └── service │ ├── SimpleAnonCredUtils.h │ ├── SimpleAnonCredClientDemo.cpp │ ├── SimpleAnonCredUtils.cpp │ ├── SimpleAnonCredServer.cpp │ ├── SimpleAnonCredServiceHandler.h │ ├── SimpleAnonCredClient.h │ ├── SimpleAnonCredServiceHandler.cpp │ └── SimpleAnonCredClient.cpp ├── LICENSE ├── CONTRIBUTING.md ├── service.thrift ├── Makefile ├── CODE_OF_CONDUCT.md ├── commit_log.txt ├── tests ├── dleqproof_test.cpp ├── kdf_test.cpp └── voprf_test.cpp ├── docs └── ARCHITECTURE.md └── README.md /Dockerfile: -------------------------------------------------------------------------------- 1 | ARG UBUNTU_VERSION 2 | 3 | FROM ubuntu:${UBUNTU_VERSION} 4 | 5 | WORKDIR /root 6 | RUN apt-get update && \ 7 | apt-get install -y libthrift-0.16.0 thrift-compiler g++ \ 8 | libboost-dev libthrift-dev libsodium-dev make 9 | 10 | COPY . . 11 | 12 | RUN make all 13 | 14 | ENV PATH="${WORKDIR}:${PATH}" 15 | 16 | CMD ["server"] 17 | -------------------------------------------------------------------------------- /src/crypto/curve/curve_ed25519.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #pragma once 9 | 10 | #include "src/crypto/curve/curve.h" 11 | 12 | /** 13 | * Implementation for curve ed25519. 14 | * Example: 15 | * curve_t c; 16 | * curve_ed25519_init(&c); 17 | * unsigned char r[c.scalar_bytes]; 18 | * c.scalar_random(r, c.scalar_bytes); 19 | */ 20 | 21 | void curve_ed25519_init(curve_t* /* curve */); 22 | -------------------------------------------------------------------------------- /src/service/SimpleAnonCredUtils.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #pragma once 9 | 10 | #include 11 | #include 12 | 13 | namespace anon_cred { 14 | namespace util { 15 | std::string binToHex(const std::vector& bin); 16 | std::vector hexToBin( 17 | const std::string& hex, 18 | size_t desiredBinSize = 0); 19 | } // namespace util 20 | } // namespace anon_cred 21 | -------------------------------------------------------------------------------- /src/crypto/kdf/kdf_naor_reingold.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | 10 | #include "src/crypto/kdf/kdf.h" 11 | 12 | /** 13 | * Implementation for KDF naor reingold. 14 | * 15 | * This is a KDF inspired by the Naor-Reingold PRF. The size of primary keys are 16 | * relatively large (about 256 * kdf_sdhi). 17 | * 18 | * See https://research.fb.com/dit for details. 19 | */ 20 | 21 | void kdf_naor_reingold_init(kdf_t* /* kdf */, curve_t* /* curve */); 22 | -------------------------------------------------------------------------------- /src/crypto/kdf/kdf_sdhi.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | 10 | #include "src/crypto/kdf/kdf.h" 11 | 12 | /** 13 | * Implementation for KDF sdhi. 14 | * . primary private key (psk): random generated 15 | * . primary public key: ppk = g^psk 16 | * . primary key: primary_key = ppk || psk 17 | * . private key: sk = 1 / (psk + hash(attr[0], attr[1], ...)) 18 | * . public key: pk = g^sk 19 | */ 20 | 21 | void kdf_sdhi_init(kdf_t* /* kdf */, curve_t* /* curve */); 22 | -------------------------------------------------------------------------------- /src/crypto/kdf/kdf_default.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | 10 | #include "src/crypto/kdf/kdf.h" 11 | 12 | /** 13 | * Implementation for KDF default. 14 | * Note: This KDF does NOT support public key proof. 15 | * 16 | * . primary key: random generated 17 | * . private key: sk = hash(primary_key, attr[0], attr[1], ...) 18 | * . public key: pk = g^sk, where g is the generator of the curve 19 | */ 20 | 21 | void kdf_default_init(kdf_t* /* kdf */, curve_t* /* curve */); 22 | -------------------------------------------------------------------------------- /src/crypto/curve/curve_ristretto.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #pragma once 9 | 10 | #include "src/crypto/curve/curve.h" 11 | 12 | #ifdef __cplusplus 13 | extern "C" { 14 | #endif 15 | 16 | /** 17 | * Implementation for curve ristretto. 18 | * Example: 19 | * curve_t c; 20 | * curve_ristretto_init(&c); 21 | * unsigned char r[c.scalar_bytes]; 22 | * c.scalar_random(r, c.scalar_bytes); 23 | */ 24 | 25 | void curve_ristretto_init(curve_t* /* curve */); 26 | 27 | #ifdef __cplusplus 28 | } 29 | #endif 30 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | MIT License 2 | 3 | Copyright (c) Meta Platforms, Inc. and affiliates. 4 | 5 | Permission is hereby granted, free of charge, to any person obtaining a copy 6 | of this software and associated documentation files (the "Software"), to deal 7 | in the Software without restriction, including without limitation the rights 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 9 | copies of the Software, and to permit persons to whom the Software is 10 | furnished to do so, subject to the following conditions: 11 | 12 | The above copyright notice and this permission notice shall be included in all 13 | copies or substantial portions of the Software. 14 | 15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 21 | SOFTWARE. 22 | -------------------------------------------------------------------------------- /src/service/SimpleAnonCredClientDemo.cpp: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | #include 10 | #include 11 | #include "demo/SimpleAnonCredClient.h" 12 | 13 | int main() { 14 | std::shared_ptr socket( 15 | new apache::thrift::transport::TSocket("127.0.0.1", 9090)); 16 | std::shared_ptr transport( 17 | new apache::thrift::transport::TBufferedTransport(socket)); 18 | std::shared_ptr protocol( 19 | new apache::thrift::protocol::TBinaryProtocol(transport)); 20 | anon_cred::SimpleAnonCredClient client(protocol); 21 | transport->open(); 22 | 23 | std::string token = "test_credential"; 24 | std::vector attributes = {"some", "random", "attributes"}; 25 | 26 | client.getPrimaryPublicKey(); 27 | client.getPublicKey(attributes); 28 | client.getCredential(token, attributes); 29 | client.redeemCredential(token, attributes); 30 | return 0; 31 | } 32 | -------------------------------------------------------------------------------- /src/crypto/voprf/voprf_mul_twohashdh.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #pragma once 9 | 10 | #include "src/crypto/voprf/voprf.h" 11 | 12 | /** 13 | * (Double) Hashed Diffie-Hellman (two hash DH) implementations with 14 | * multiplactive blinding. 15 | * . (client) blind: 16 | * . pick random scalar r 17 | * . blinded_element = hash_1(input) * g^r 18 | * . (server) evaluate: 19 | * . evaluated_element = blinded_element ^ sk 20 | * . (client) unblind: 21 | * . unblinded_element = evaluated_element * pk^(-r) 22 | * . = hash_1(input) ^ sk 23 | * . (client) client_finalize: 24 | * . client_final_evaluation = hash_2(input, unblinded_element) 25 | * . (server) server_finalize: 26 | * . server_final_evaluation = hash_2(input, hash_1(input) ^ sk) 27 | * . client_final_evaluation and server_final_evaluation should match 28 | * 29 | * Example with curve ed25519: 30 | * curve_t c; 31 | * voprf_t v; 32 | * curve_ed25519_init(&c); 33 | * voprf_mul_twohashdh_init(&v, &c); 34 | * v.blind(&v, ...); 35 | */ 36 | 37 | void voprf_mul_twohashdh_init(voprf_t* /* voprf */, curve_t* /* curve */); 38 | -------------------------------------------------------------------------------- /CONTRIBUTING.md: -------------------------------------------------------------------------------- 1 | # Contributing to acs 2 | We want to make contributing to this project as easy and transparent as 3 | possible. 4 | 5 | ## Pull Requests 6 | We actively welcome your pull requests. 7 | 8 | 1. Fork the repo and create your branch from `main`. 9 | 2. If you've added code that should be tested, add tests. 10 | 3. If you've changed APIs, update the documentation. 11 | 4. Ensure the test suite passes. 12 | 5. Make sure your code lints. 13 | 6. If you haven't already, complete the Contributor License Agreement ("CLA"). 14 | 15 | ## Contributor License Agreement ("CLA") 16 | In order to accept your pull request, we need you to submit a CLA. You only need 17 | to do this once to work on any of Facebook's open source projects. 18 | 19 | Complete your CLA here: 20 | 21 | ## Issues 22 | We use GitHub issues to track public bugs. Please ensure your description is 23 | clear and has sufficient instructions to be able to reproduce the issue. 24 | 25 | Facebook has a [bounty program](https://www.facebook.com/whitehat/) for the safe 26 | disclosure of security bugs. In those cases, please go through the process 27 | outlined on that page and do not file a public issue. 28 | 29 | ## License 30 | By contributing to acs, you agree that your contributions will be licensed 31 | under the LICENSE file in the root directory of this source tree. 32 | -------------------------------------------------------------------------------- /src/service/SimpleAnonCredUtils.cpp: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include "demo/SimpleAnonCredUtils.h" 9 | #include 10 | #include "gen-cpp/service_types.h" 11 | 12 | namespace anon_cred { 13 | namespace util { 14 | std::string binToHex(const std::vector& bin) { 15 | char buf[bin.size() * 2 + 1]; 16 | sodium_bin2hex(buf, bin.size() * 2 + 1, bin.data(), bin.size()); 17 | return std::string(buf); 18 | } 19 | 20 | std::vector hexToBin( 21 | const std::string& hex, 22 | size_t desiredBinSize) { 23 | std::vector bin( 24 | desiredBinSize == 0 ? hex.size() : desiredBinSize); 25 | size_t length; 26 | if (sodium_hex2bin( 27 | bin.data(), 28 | bin.size(), 29 | hex.data(), 30 | hex.size(), 31 | nullptr, 32 | &length, 33 | nullptr) != 0 || 34 | (desiredBinSize != 0 && desiredBinSize != length)) { 35 | thrift::TokenEncodingException exception; 36 | exception.message = "Failed to convert token " + hex + " to binary"; 37 | throw exception; 38 | } 39 | bin.resize(length); 40 | return bin; 41 | } 42 | } // namespace util 43 | } // namespace anon_cred 44 | -------------------------------------------------------------------------------- /src/crypto/voprf/voprf_exp_twohashdh.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #pragma once 9 | 10 | #include "src/crypto/voprf/voprf.h" 11 | 12 | #ifdef __cplusplus 13 | extern "C" { 14 | #endif 15 | 16 | /** 17 | * (Double) Hashed Diffie-Hellman (two hash DH) implementations with 18 | * exponential blinding. 19 | * . (client) blind: 20 | * . pick random scalar r 21 | * . blinded_element = hash_1(input) ^ r 22 | * . (server) evaluate: 23 | * . evaluated_element = blinded_element ^ sk 24 | * . (client) unblind: 25 | * . unblinded_element = evaluated_element ^ (1/r) 26 | * . = hash_1(input) ^ sk 27 | * . (client) client_finalize: 28 | * . client_final_evaluation = hash_2(input, unblinded_element) 29 | * . (server) server_finalize: 30 | * . server_final_evaluation = hash_2(input, hash_1(input) ^ sk) 31 | * . client_final_evaluation and server_final_evaluation should match 32 | * 33 | * Example with curve ed25519: 34 | * curve_t c; 35 | * voprf_t v; 36 | * curve_ed25519_init(&c); 37 | * voprf_exp_twohashdh_init(&v, &c); 38 | * v.blind(&v, ...); 39 | */ 40 | 41 | void voprf_exp_twohashdh_init(voprf_t* /* voprf */, curve_t* /* curve */); 42 | 43 | #ifdef __cplusplus 44 | } 45 | #endif 46 | -------------------------------------------------------------------------------- /src/service/SimpleAnonCredServer.cpp: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | #include 10 | #include 11 | #include 12 | #include "demo/SimpleAnonCredServiceHandler.h" 13 | #include "gen-cpp/SimpleAnonCredService.h" 14 | 15 | using namespace ::apache::thrift; 16 | using namespace ::apache::thrift::protocol; 17 | using namespace ::apache::thrift::transport; 18 | using namespace ::apache::thrift::server; 19 | using namespace ::anon_cred; 20 | 21 | int main(int argc, char** argv) { 22 | int port = 9090; 23 | ::std::shared_ptr handler( 24 | new SimpleAnonCredServiceHandler()); 25 | ::std::shared_ptr processor( 26 | new SimpleAnonCredServiceProcessor(handler)); 27 | ::std::shared_ptr serverTransport(new TServerSocket(port)); 28 | ::std::shared_ptr transportFactory( 29 | new TBufferedTransportFactory()); 30 | ::std::shared_ptr protocolFactory( 31 | new TBinaryProtocolFactory()); 32 | 33 | TSimpleServer server( 34 | processor, serverTransport, transportFactory, protocolFactory); 35 | server.serve(); 36 | return 0; 37 | } 38 | -------------------------------------------------------------------------------- /src/service/SimpleAnonCredServiceHandler.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #pragma once 9 | 10 | #include "gen-cpp/SimpleAnonCredService.h" 11 | 12 | extern "C" { 13 | #include "src/crypto/curve/curve_ristretto.h" 14 | #include "src/crypto/kdf/kdf_sdhi.h" 15 | #include "src/crypto/voprf/voprf_mul_twohashdh.h" 16 | } 17 | 18 | namespace anon_cred { 19 | 20 | using namespace thrift; 21 | 22 | class SimpleAnonCredServiceHandler : virtual public SimpleAnonCredServiceIf { 23 | public: 24 | SimpleAnonCredServiceHandler(); 25 | void getPrimaryPublicKey(GetPrimaryPublicKeyResponse& response); 26 | void getPublicKeyAndProof( 27 | GetPublicKeyResponse& response, 28 | const GetPublicKeyRequest& request); 29 | void signCredential( 30 | SignCredentialResponse& response, 31 | const SignCredentialRequest& request); 32 | void redeemCredential(const RedeemCredentialRequest& request); 33 | 34 | private: 35 | void deriveKeyPair( 36 | std::vector& sk, 37 | std::vector& pk, 38 | std::vector& pkProof, 39 | const std::vector& attributes); 40 | 41 | curve_t curve_; 42 | voprf_t voprf_; 43 | kdf_t kdf_; 44 | 45 | std::vector primaryKey_; 46 | }; 47 | 48 | } // namespace anon_cred 49 | -------------------------------------------------------------------------------- /src/service/SimpleAnonCredClient.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #pragma once 9 | 10 | #include 11 | #include 12 | #include 13 | #include 14 | #include 15 | #include "gen-cpp/SimpleAnonCredService.h" 16 | 17 | extern "C" { 18 | #include "src/crypto/curve/curve_ristretto.h" 19 | #include "src/crypto/kdf/kdf_sdhi.h" 20 | #include "src/crypto/voprf/voprf_mul_twohashdh.h" 21 | } 22 | 23 | namespace anon_cred { 24 | 25 | class SimpleAnonCredClient { 26 | public: 27 | SimpleAnonCredClient( 28 | std::shared_ptr<::apache::thrift::protocol::TProtocol> prot); 29 | void getPrimaryPublicKey(); 30 | void getPublicKey(const std::vector& attributes); 31 | void getCredential( 32 | const std::string& cred, 33 | const std::vector& attributes); 34 | void redeemCredential( 35 | const std::string& cred, 36 | const std::vector& attributes); 37 | 38 | std::vector primaryPublicKey; 39 | std::vector publicKey; 40 | std::vector unBlindedElement; 41 | 42 | private: 43 | curve_t curve_; 44 | voprf_t voprf_; 45 | kdf_t kdf_; 46 | thrift::SimpleAnonCredServiceClient thriftClient_; 47 | }; 48 | 49 | } // namespace anon_cred 50 | -------------------------------------------------------------------------------- /src/crypto/voprf/voprf_twohashdh.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include "src/crypto/voprf/voprf.h" 9 | 10 | /* 11 | This is a header for helper functions used in voprf_exp_twohashdh and 12 | voprf_mul_twohashdh. Do not use this as an implementation directly 13 | */ 14 | 15 | enum voprf_error setup( 16 | voprf_t* voprf, 17 | unsigned char* sk, 18 | size_t sk_len, 19 | unsigned char* pk, 20 | size_t pk_len); 21 | 22 | enum voprf_error evaluate( 23 | voprf_t* voprf, 24 | unsigned char* evaluated_element, 25 | size_t evaluated_element_len, 26 | unsigned char* proof_c, 27 | size_t proof_c_len, 28 | unsigned char* proof_s, 29 | size_t proof_s_len, 30 | const unsigned char* sk, 31 | size_t sk_len, 32 | const unsigned char* blinded_element, 33 | size_t blinded_element_len, 34 | int flag_proof_generate); 35 | 36 | enum voprf_error client_finalize( 37 | voprf_t* voprf, 38 | unsigned char* final_evaluation, 39 | size_t final_evaluation_len, 40 | const unsigned char* input, 41 | size_t input_len, 42 | const unsigned char* unblinded_element, 43 | size_t unblinded_element_len); 44 | 45 | enum voprf_error server_finalize( 46 | voprf_t* voprf, 47 | unsigned char* final_evaluation, 48 | size_t final_evaluation_len, 49 | const unsigned char* input, 50 | size_t input_len, 51 | const unsigned char* sk, 52 | size_t sk_len); 53 | -------------------------------------------------------------------------------- /service.thrift: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | /** 9 | * Apache Thrift interface for demo server. 10 | * 11 | * Tested with Apache Thrift v0.16.0 12 | */ 13 | 14 | namespace cpp anon_cred.thrift 15 | 16 | exception AnonCredServiceException { 17 | 1: string message; 18 | } 19 | 20 | exception TokenEncodingException { 21 | 1: string message; 22 | } 23 | 24 | exception VoprfErrorException { 25 | 1: string message; 26 | 2: i32 errorcode; 27 | } 28 | 29 | exception CredentialMismatchException { 30 | 1: string message; 31 | } 32 | 33 | struct GetPrimaryPublicKeyResponse { 34 | 1: string primay_public_key; 35 | } 36 | 37 | struct GetPublicKeyRequest { 38 | 1: list attributes; 39 | } 40 | 41 | struct GetPublicKeyResponse { 42 | 1: string public_key; 43 | 2: string public_key_proof; 44 | } 45 | 46 | struct SignCredentialRequest { 47 | 1: string blinded_token; 48 | 2: list attributes; 49 | } 50 | 51 | struct SignCredentialResponse { 52 | 1: string evaluated_token; 53 | 2: string proof_c; 54 | 3: string proof_s; 55 | } 56 | 57 | struct RedeemCredentialRequest { 58 | 1: string token; 59 | 2: string shared_secret; 60 | 3: list attributes; 61 | } 62 | 63 | service SimpleAnonCredService { 64 | // Client gets a primary public key from server 65 | GetPrimaryPublicKeyResponse getPrimaryPublicKey(); 66 | // Client gets a public key and pk_proof from server 67 | GetPublicKeyResponse getPublicKeyAndProof(1: GetPublicKeyRequest request); 68 | // Client sends a blinded token to server and gets a evaluated token 69 | SignCredentialResponse signCredential( 70 | 1: SignCredentialRequest request, 71 | ) throws ( 72 | 1: TokenEncodingException tokenEncodingException, 73 | 2: VoprfErrorException voprfErrorException, 74 | ); 75 | // Client redeems token with shared_secret. Server validates the token 76 | void redeemCredential(1: RedeemCredentialRequest request) throws ( 77 | 1: TokenEncodingException tokenEncodingException, 78 | 2: VoprfErrorException voprfErrorException, 79 | 3: CredentialMismatchException credentialMismatchException, 80 | ); 81 | } 82 | -------------------------------------------------------------------------------- /Makefile: -------------------------------------------------------------------------------- 1 | CC = gcc 2 | CFLAGS = -O2 -I. 3 | CXX = g++ 4 | CXX_FLAGS = -O2 --std=c++17 -I. 5 | CXX_LIBS = -lthrift -lsodium 6 | 7 | ######################################## 8 | 9 | THRIFT_PATH = gen-cpp 10 | _THRIFT_OBJS = service_types.o SimpleAnonCredService.o 11 | THRIFT_OBJS = $(foreach n, $(_THRIFT_OBJS), $(THRIFT_PATH)/$(n)) 12 | 13 | ######################################## 14 | 15 | CURVE_PATH = src/crypto/curve 16 | VOPRF_PATH = src/crypto/voprf 17 | KDF_PATH = src/crypto/kdf 18 | DLEQPROOF_PATH = src/crypto/dleqproof 19 | 20 | _CURVE_OBJS = curve_ristretto.o 21 | _VOPRF_OBJS = voprf_mul_twohashdh.o voprf_twohashdh.o 22 | _KDF_OBJS = kdf_sdhi.o 23 | _DLEQPROOF_OBJS = dleqproof.o 24 | 25 | 26 | CRYPTO_OBJS = $(foreach n, $(_CURVE_OBJS), $(CURVE_PATH)/$(n)) \ 27 | $(foreach n, $(_VOPRF_OBJS), $(VOPRF_PATH)/$(n)) \ 28 | $(foreach n, $(_KDF_OBJS), $(KDF_PATH)/$(n)) \ 29 | $(foreach n, $(_DLEQPROOF_OBJS), $(DLEQPROOF_PATH)/$(n)) 30 | 31 | ######################################## 32 | 33 | SERVER_PATH = src/service 34 | _SERVER_OBJS = SimpleAnonCredServiceHandler.o 35 | SERVER_OBJS = $(foreach n, $(_SERVER_OBJS), $(SERVER_PATH)/$(n)) 36 | SERVER_TARGET = server 37 | 38 | CLIENT_PATH = src/service 39 | _CLIENT_OBJS = SimpleAnonCredClient.o 40 | CLIENT_OBJS = $(foreach n, $(_CLIENT_OBJS), $(CLIENT_PATH)/$(n)) 41 | CLIENT_TARGET = client 42 | 43 | UTIL_PATH = src/service 44 | _UTIL_OBJS = SimpleAnonCredUtils.o 45 | UTIL_OBJS = $(foreach n, $(_UTIL_OBJS), $(UTIL_PATH)/$(n)) 46 | 47 | ######################################## 48 | 49 | TEST_PATH = tests 50 | _TEST_SOURCES = dleqproof_test.cpp kdf_test.cpp voprf_test.cpp 51 | TEST_SOURCES = $(foreach n, $(_TEST_SOURCES), $(TEST_PATH)/$(n)) 52 | TEST_TARGETS = $(TEST_SOURCES:.cpp=) 53 | 54 | ######################################## 55 | 56 | all: thrift $(SERVER_TARGET) $(CLIENT_TARGET) 57 | 58 | tests: $(TEST_TARGETS) 59 | 60 | thrift: service.thrift 61 | thrift --gen cpp $< 62 | 63 | $(SERVER_TARGET): $(CRYPTO_OBJS) $(THRIFT_OBJS) $(UTIL_OBJS) $(SERVER_OBJS) $(SERVER_PATH)/SimpleAnonCredServer.cpp 64 | $(CXX) $(CXX_FLAGS) $^ -o $@ $(CXX_LIBS) 65 | 66 | $(CLIENT_TARGET): $(CRYPTO_OBJS) $(THRIFT_OBJS) $(UTIL_OBJS) $(CLIENT_OBJS) $(CLIENT_PATH)/SimpleAnonCredClientDemo.cpp 67 | $(CXX) $(CXX_FLAGS) $^ -o $@ $(CXX_LIBS) 68 | 69 | $(CURVE_PATH)/%.o: $(CURVE_PATH)/%.c 70 | $(CC) $(CFLAGS) -c -o $@ $< 71 | 72 | $(VOPRF_PATH)/%.o: $(VOPRF_PATH)/%.c 73 | $(CC) $(CFLAGS) -c -o $@ $< 74 | 75 | $(KDF_PATH)/%.o: $(KDF_PATH)/%.c 76 | $(CC) $(CFLAGS) -c -o $@ $< 77 | 78 | $(DLEQPROOF_PATH)/%.o: $(DLEQPROOF_PATH)/%.c 79 | $(CC) $(CFLAGS) -c -o $@ $< 80 | 81 | %.o: %.cpp 82 | $(CXX) $(CXX_FLAGS) -c -o $@ $< 83 | 84 | $(TEST_PATH)/%: $(TEST_PATH)/%.cpp $(CRYPTO_OBJS) 85 | $(CXX) $(CXX_FLAGS) $^ -o $@ $(CXX_LIBS) 86 | 87 | .PHONY: clean tests 88 | clean: 89 | rm -f $(CRYPTO_OBJS) $(THRIFT_OBJS) 90 | rm -f $(SERVER_OBJS) $(CLIENT_OBJS) $(UTIL_OBJS) 91 | rm -f $(TEST_TARGETS) 92 | rm -f $(SERVER_TARGET) $(CLIENT_TARGET) 93 | rm -rf $(THRIFT_PATH) 94 | -------------------------------------------------------------------------------- /CODE_OF_CONDUCT.md: -------------------------------------------------------------------------------- 1 | # Code of Conduct 2 | 3 | ## Our Pledge 4 | 5 | In the interest of fostering an open and welcoming environment, we as 6 | contributors and maintainers pledge to make participation in our project and 7 | our community a harassment-free experience for everyone, regardless of age, body 8 | size, disability, ethnicity, sex characteristics, gender identity and expression, 9 | level of experience, education, socio-economic status, nationality, personal 10 | appearance, race, religion, or sexual identity and orientation. 11 | 12 | ## Our Standards 13 | 14 | Examples of behavior that contributes to creating a positive environment 15 | include: 16 | 17 | * Using welcoming and inclusive language 18 | * Being respectful of differing viewpoints and experiences 19 | * Gracefully accepting constructive criticism 20 | * Focusing on what is best for the community 21 | * Showing empathy towards other community members 22 | 23 | Examples of unacceptable behavior by participants include: 24 | 25 | * The use of sexualized language or imagery and unwelcome sexual attention or 26 | advances 27 | * Trolling, insulting/derogatory comments, and personal or political attacks 28 | * Public or private harassment 29 | * Publishing others' private information, such as a physical or electronic 30 | address, without explicit permission 31 | * Other conduct which could reasonably be considered inappropriate in a 32 | professional setting 33 | 34 | ## Our Responsibilities 35 | 36 | Project maintainers are responsible for clarifying the standards of acceptable 37 | behavior and are expected to take appropriate and fair corrective action in 38 | response to any instances of unacceptable behavior. 39 | 40 | Project maintainers have the right and responsibility to remove, edit, or 41 | reject comments, commits, code, wiki edits, issues, and other contributions 42 | that are not aligned to this Code of Conduct, or to ban temporarily or 43 | permanently any contributor for other behaviors that they deem inappropriate, 44 | threatening, offensive, or harmful. 45 | 46 | ## Scope 47 | 48 | This Code of Conduct applies within all project spaces, and it also applies when 49 | an individual is representing the project or its community in public spaces. 50 | Examples of representing a project or community include using an official 51 | project e-mail address, posting via an official social media account, or acting 52 | as an appointed representative at an online or offline event. Representation of 53 | a project may be further defined and clarified by project maintainers. 54 | 55 | This Code of Conduct also applies outside the project spaces when there is a 56 | reasonable belief that an individual's behavior may have a negative impact on 57 | the project or its community. 58 | 59 | ## Enforcement 60 | 61 | Instances of abusive, harassing, or otherwise unacceptable behavior may be 62 | reported by contacting the project team at . All 63 | complaints will be reviewed and investigated and will result in a response that 64 | is deemed necessary and appropriate to the circumstances. The project team is 65 | obligated to maintain confidentiality with regard to the reporter of an incident. 66 | Further details of specific enforcement policies may be posted separately. 67 | 68 | Project maintainers who do not follow or enforce the Code of Conduct in good 69 | faith may face temporary or permanent repercussions as determined by other 70 | members of the project's leadership. 71 | 72 | ## Attribution 73 | 74 | This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4, 75 | available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html 76 | 77 | [homepage]: https://www.contributor-covenant.org 78 | 79 | For answers to common questions about this code of conduct, see 80 | https://www.contributor-covenant.org/faq 81 | -------------------------------------------------------------------------------- /src/crypto/kdf/kdf_default.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | #include 10 | 11 | #include "src/crypto/curve/curve.h" 12 | #include "src/crypto/dleqproof/dleqproof.h" 13 | #include "src/crypto/kdf/kdf.h" 14 | #include "src/crypto/kdf/kdf_default.h" 15 | 16 | #define CURVE_SUCCESS_CHECK(EXP) \ 17 | if (EXP != CURVE_SUCCESS) { \ 18 | return KDF_CURVE_OPERATION_ERROR; \ 19 | } 20 | 21 | static enum kdf_error generate_primary_key( 22 | kdf_t* kdf, 23 | unsigned char* primary_key, 24 | size_t primary_key_len) { 25 | if (primary_key_len != kdf->primary_key_bytes) { 26 | return KDF_BUFFER_LENGTH_ERROR; 27 | } 28 | randombytes_buf((void*)primary_key, primary_key_len); 29 | return KDF_SUCCESS; 30 | } 31 | 32 | static enum kdf_error derive_key_pair( 33 | kdf_t* kdf, 34 | unsigned char* sk, 35 | size_t sk_len, 36 | unsigned char* pk, 37 | size_t pk_len, 38 | unsigned char* pk_proof, 39 | size_t pk_proof_len, 40 | const unsigned char* primary_key, 41 | size_t primary_key_len, 42 | int n_attributes, 43 | const unsigned char** attribute_arr, 44 | const size_t* attribute_len_arr, 45 | int flag_pk_proof_generate) { 46 | const size_t scalar_bytes = kdf->curve->scalar_bytes; 47 | const size_t element_bytes = kdf->curve->element_bytes; 48 | 49 | if (sk_len != scalar_bytes || pk_len != element_bytes || 50 | primary_key_len != kdf->primary_key_bytes) { 51 | return KDF_BUFFER_LENGTH_ERROR; 52 | } 53 | // Hash attribute to attribute secret key scalar 54 | unsigned char round_hmac_key[crypto_auth_hmacsha256_KEYBYTES]; 55 | unsigned char out[crypto_auth_hmacsha256_BYTES]; 56 | 57 | memcpy(round_hmac_key, primary_key, crypto_auth_hmacsha256_KEYBYTES); 58 | for (int i = 0; i < n_attributes; ++i) { 59 | crypto_auth_hmacsha256( 60 | out, attribute_arr[i], attribute_len_arr[i], round_hmac_key); 61 | memcpy(round_hmac_key, out, crypto_auth_hmacsha256_KEYBYTES); 62 | } 63 | 64 | CURVE_SUCCESS_CHECK(kdf->curve->hash_to_scalar( 65 | sk, 66 | (const unsigned char*[]){out}, 67 | (const size_t[]){crypto_auth_hmacsha256_BYTES}, 68 | 1)); 69 | CURVE_SUCCESS_CHECK(kdf->curve->group_exp_generator(pk, pk_len, sk, sk_len)); 70 | 71 | sodium_memzero(round_hmac_key, crypto_auth_hmacsha256_KEYBYTES); 72 | sodium_memzero(out, crypto_auth_hmacsha256_BYTES); 73 | 74 | return KDF_SUCCESS; 75 | } 76 | 77 | static enum kdf_error verify_public_key( 78 | kdf_t* kdf, 79 | const unsigned char* pk, 80 | size_t pk_len, 81 | const unsigned char* pk_proof, 82 | size_t pk_proof_len, 83 | const unsigned char* ppk, 84 | size_t ppk_len, 85 | int n_attributes, 86 | const unsigned char** attribute_arr, 87 | const size_t* attribute_len_arr) { 88 | return KDF_SUCCESS; 89 | } 90 | 91 | static enum kdf_error derive_primary_public_key( 92 | kdf_t* kdf, 93 | unsigned char* ppk, 94 | size_t ppk_len, 95 | const unsigned char* primary_key, 96 | size_t primary_key_len) { 97 | return KDF_SUCCESS; 98 | } 99 | 100 | void kdf_default_init(kdf_t* kdf, curve_t* curve) { 101 | kdf->curve = curve; 102 | kdf->primary_private_key_bytes = crypto_auth_hmacsha256_KEYBYTES; 103 | kdf->primary_public_key_bytes = 0; 104 | kdf->primary_key_bytes = crypto_auth_hmacsha256_KEYBYTES; 105 | kdf->public_key_proof_bytes = 0; 106 | kdf->generate_primary_key = generate_primary_key; 107 | kdf->derive_key_pair = derive_key_pair; 108 | kdf->verify_public_key = verify_public_key; 109 | kdf->derive_primary_public_key = derive_primary_public_key; 110 | } 111 | -------------------------------------------------------------------------------- /commit_log.txt: -------------------------------------------------------------------------------- 1 | Commit on 2022-01-15 - 1763926298 2 | Commit on 2022-01-30 - 1763926298 3 | Commit on 2022-01-29 - 1763926298 4 | Commit on 2022-03-10 - 1763926298 5 | Commit on 2022-03-08 - 1763926298 6 | Commit on 2022-03-31 - 1763926298 7 | 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2025-05-25 - 1763926305 110 | Commit on 2025-06-03 - 1763926305 111 | Commit on 2025-06-06 - 1763926305 112 | Commit on 2025-06-23 - 1763926305 113 | Commit on 2025-07-05 - 1763926305 114 | Commit on 2025-09-07 - 1763926305 115 | Commit on 2025-09-06 - 1763926305 116 | Commit on 2025-09-16 - 1763926305 117 | Commit on 2025-09-26 - 1763926305 118 | Commit on 2025-09-21 - 1763926306 119 | -------------------------------------------------------------------------------- /src/crypto/voprf/voprf_exp_twohashdh.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | 10 | #include "src/crypto/curve/curve.h" 11 | #include "src/crypto/dleqproof/dleqproof.h" 12 | #include "src/crypto/voprf/voprf_exp_twohashdh.h" 13 | #include "src/crypto/voprf/voprf_twohashdh.h" 14 | 15 | #define CURVE_SUCCESS_CHECK(EXP) \ 16 | if (EXP != CURVE_SUCCESS) { \ 17 | return VOPRF_CURVE_OPERATION_ERROR; \ 18 | } 19 | 20 | static enum voprf_error blind( 21 | struct voprf* voprf, 22 | unsigned char* blinded_element, 23 | size_t blinded_element_len, 24 | unsigned char* blinding_factor, 25 | size_t blinding_factor_len, 26 | const unsigned char* input, 27 | size_t input_len) { 28 | size_t element_bytes = voprf->curve->element_bytes; 29 | size_t scalar_bytes = voprf->curve->scalar_bytes; 30 | if (blinded_element_len != element_bytes || 31 | blinding_factor_len != scalar_bytes) { 32 | return VOPRF_BUFFER_LENGTH_ERROR; 33 | } 34 | 35 | // Sample random blinding factor 36 | CURVE_SUCCESS_CHECK( 37 | voprf->curve->scalar_random(blinding_factor, blinding_factor_len)); 38 | 39 | unsigned char hashed_message_point[element_bytes]; 40 | 41 | // Hash and blind input 42 | CURVE_SUCCESS_CHECK(voprf->curve->hash_to_curve( 43 | hashed_message_point, 44 | (const unsigned char*[]){input}, 45 | (const size_t[]){input_len}, 46 | 1)); 47 | CURVE_SUCCESS_CHECK(voprf->curve->group_exp( 48 | blinded_element, 49 | blinded_element_len, 50 | blinding_factor, 51 | blinded_element_len, 52 | hashed_message_point, 53 | element_bytes)); 54 | return VOPRF_SUCCESS; 55 | } 56 | 57 | static enum voprf_error verifiable_unblind( 58 | struct voprf* voprf, 59 | unsigned char* unblinded_element, 60 | size_t unblinded_element_len, 61 | const unsigned char* proof_c, 62 | size_t proof_c_len, 63 | const unsigned char* proof_s, 64 | size_t proof_s_len, 65 | const unsigned char* blinding_factor, 66 | size_t blinding_factor_len, 67 | const unsigned char* evaluated_element, 68 | size_t evaluated_element_len, 69 | const unsigned char* blinded_element, 70 | size_t blinded_element_len, 71 | const unsigned char* pk, 72 | size_t pk_len, 73 | int flag_proof_verify) { 74 | size_t element_bytes = voprf->curve->element_bytes; 75 | size_t scalar_bytes = voprf->curve->scalar_bytes; 76 | if (unblinded_element_len != element_bytes || 77 | blinding_factor_len != scalar_bytes || 78 | evaluated_element_len != element_bytes || 79 | blinded_element_len != element_bytes) { 80 | return VOPRF_BUFFER_LENGTH_ERROR; 81 | } 82 | CURVE_SUCCESS_CHECK( 83 | voprf->curve->check_on_curve(evaluated_element, evaluated_element_len)); 84 | CURVE_SUCCESS_CHECK( 85 | voprf->curve->check_on_curve(blinded_element, blinded_element_len)); 86 | 87 | // Verify proof 88 | if (flag_proof_verify) { 89 | if (proof_c == NULL || proof_s == NULL) { 90 | return VOPRF_PROOF_ERROR; 91 | } 92 | if (proof_c_len != scalar_bytes || proof_s_len != scalar_bytes || 93 | pk_len != element_bytes) { 94 | return VOPRF_BUFFER_LENGTH_ERROR; 95 | } 96 | 97 | const size_t generator_len = voprf->curve->element_bytes; 98 | unsigned char generator[generator_len]; 99 | CURVE_SUCCESS_CHECK(voprf->curve->get_generator(generator, generator_len)); 100 | dleqproof_protocol_t dleqproof; 101 | dleqproof_init(&dleqproof, voprf->curve); 102 | if (dleqproof.verify( 103 | &dleqproof, 104 | proof_c, 105 | proof_c_len, 106 | proof_s, 107 | proof_s_len, 108 | generator, 109 | generator_len, 110 | blinded_element, 111 | blinded_element_len, 112 | pk, 113 | pk_len, 114 | evaluated_element, 115 | evaluated_element_len) != DLEQPROOF_SUCCESS) { 116 | return VOPRF_PROOF_ERROR; 117 | } 118 | } 119 | 120 | // Unblind evaluation 121 | unsigned char inv_blinding_factor[voprf->curve->scalar_bytes]; 122 | 123 | CURVE_SUCCESS_CHECK(voprf->curve->scalar_inv( 124 | inv_blinding_factor, scalar_bytes, blinding_factor, blinding_factor_len)); 125 | CURVE_SUCCESS_CHECK(voprf->curve->group_exp( 126 | unblinded_element, 127 | unblinded_element_len, 128 | inv_blinding_factor, 129 | scalar_bytes, 130 | evaluated_element, 131 | evaluated_element_len)); 132 | return VOPRF_SUCCESS; 133 | } 134 | 135 | void voprf_exp_twohashdh_init(voprf_t* voprf, curve_t* curve) { 136 | voprf->final_evaluation_bytes = crypto_hash_sha512_BYTES; 137 | voprf->curve = curve; 138 | voprf->setup = setup; 139 | voprf->blind = blind; 140 | voprf->evaluate = evaluate; 141 | voprf->verifiable_unblind = verifiable_unblind; 142 | voprf->client_finalize = client_finalize; 143 | voprf->server_finalize = server_finalize; 144 | } 145 | -------------------------------------------------------------------------------- /src/crypto/dleqproof/dleqproof.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #pragma once 9 | 10 | #include 11 | 12 | #include "src/crypto/curve/curve.h" 13 | 14 | enum dleqproof_error { 15 | DLEQPROOF_SUCCESS = 0, 16 | DLEQPROOF_UNKNOWN_ERROR = -1, 17 | DLEQPROOF_BUFFER_LENGTH_ERROR = 1, 18 | DLEQPROOF_CURVE_OPERATION_ERROR = 2, 19 | DLEQPROOF_VERIFY_FAIL = 3, 20 | }; 21 | 22 | /** 23 | * An interface for DLEQPROOF protocol. 24 | * 25 | * Discrete log equivalence proof (DLEQ proof) 26 | * A DLEQ proof allows the server to prove to the client that the pairs 27 | * (element1, base1) and (element2, base2) have the same discrete log relation x 28 | * (i.e. element1 = base1 ^ x, element2 = base2 ^ x) without release x to the 29 | * client. 30 | * 31 | * A default implementation is provided. 32 | */ 33 | 34 | typedef struct dleqproof_protocol dleqproof_protocol_t; 35 | 36 | struct dleqproof_protocol { 37 | /** 38 | * The elliptic curve used in this dleqproof protocol. 39 | */ 40 | curve_t* curve; 41 | 42 | /** 43 | * Computes proof from base1, base2, element1, element2, discrete_log. 44 | * proof_c = hash(base1, base2, element1, element2, base1 ^ r, base2 ^ r) 45 | * proof_s = r - proof_c * discrete_log 46 | * where r is random generated scalar. 47 | * 48 | * @param protocol A pointer to dleqproof_protocol struct. 49 | * @param proof_c Mutable unsigned char buffer for output. 50 | * @param proof_c_len The size of this buffer should be scalar_bytes of the 51 | * curve. 52 | * @param proof_s Mutable unsigned char buffer for output. 53 | * @param proof_s_len The size of this buffer should be scalar_bytes of the 54 | * curve. 55 | * @param base1 Input element 56 | * @param base1_len The size of this buffer should be element_bytes of the 57 | * curve. 58 | * @param base2 Input element 59 | * @param base2_len The size of this buffer should be element_bytes of the 60 | * curve. 61 | * @param element1 Input element 62 | * @param element1_len The size of this buffer should be element_bytes of the 63 | * curve. 64 | * @param element2 Input element 65 | * @param element2_len The size of this buffer should be element_bytes of the 66 | * curve. 67 | * @param discrete_log Input scalar 68 | * @param discrete_log_len The size of this buffer should be scalar_bytes of 69 | * the curve. 70 | * @return DLEQPROOF_SUCCESS on success. DLEQPROOF_ERROR if there are 71 | * . curve errors. 72 | */ 73 | 74 | enum dleqproof_error (*prove)( 75 | dleqproof_protocol_t* /* protocol */, 76 | unsigned char* /* proof_c */, 77 | size_t /* proof_c_len */, 78 | unsigned char* /* proof_s */, 79 | size_t /* proof_s_len */, 80 | const unsigned char* /* base1 */, 81 | size_t /* base1_len */, 82 | const unsigned char* /* base2 */, 83 | size_t /* base2_len */, 84 | const unsigned char* /* element1 */, 85 | size_t /* element1_len */, 86 | const unsigned char* /* element2 */, 87 | size_t /* element2_len */, 88 | const unsigned char* /* discrete_log */, 89 | size_t /* discrete_log_len */); 90 | 91 | /** 92 | * Verify proof with base1, base2, element1, element2. 93 | * 94 | * @param protocol A pointer to dleqproof_protocol struct. 95 | * @param proof_c Input scalar 96 | * @param proof_c_len The size of this buffer should be scalar_bytes of the 97 | * curve. 98 | * @param proof_s Input scalar 99 | * @param proof_s_len The size of this buffer should be scalar_bytes of the 100 | * curve. 101 | * @param base1 Input element 102 | * @param base1_len The size of this buffer should be element_bytes of the 103 | * curve. 104 | * @param base2 Input element 105 | * @param base2_len The size of this buffer should be element_bytes of the 106 | * curve. 107 | * @param element1 Input element 108 | * @param element1_len The size of this buffer should be element_bytes of the 109 | * curve. 110 | * @param element2 Input element 111 | * @param element2_len The size of this buffer should be element_bytes of the 112 | * curve. 113 | * @return DLEQPROOF_SUCCESS on success, DLEQPROOF_FAIL if verification fails. 114 | * DLEQPROOF_ERROR if there are curve errors. 115 | */ 116 | enum dleqproof_error (*verify)( 117 | dleqproof_protocol_t* /* protocol */, 118 | const unsigned char* /* proof_c */, 119 | size_t /* proof_c_len */, 120 | const unsigned char* /* proof_s */, 121 | size_t /* proof_s_len */, 122 | const unsigned char* /* base1 */, 123 | size_t /* base1_len */, 124 | const unsigned char* /* base2 */, 125 | size_t /* base2_len */, 126 | const unsigned char* /* element1 */, 127 | size_t /* element1_len */, 128 | const unsigned char* /* element2 */, 129 | size_t /* element2_len */); 130 | }; 131 | 132 | /** 133 | * A default dleqproof_protocal implementation. 134 | * Example with curve ed25519: 135 | * curve_t c; 136 | * dleqproof_protocol_t p; 137 | * curve_ed25519_init(&c); 138 | * dleqproof_init(&p, &c); 139 | * p.prove(&p, ...); 140 | */ 141 | 142 | void dleqproof_init(dleqproof_protocol_t* /* protocol */, curve_t* /* curve */); 143 | -------------------------------------------------------------------------------- /src/crypto/voprf/voprf_mul_twohashdh.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | 10 | #include "src/crypto/curve/curve.h" 11 | #include "src/crypto/dleqproof/dleqproof.h" 12 | #include "src/crypto/voprf/voprf_mul_twohashdh.h" 13 | #include "src/crypto/voprf/voprf_twohashdh.h" 14 | 15 | #define CURVE_SUCCESS_CHECK(EXP) \ 16 | if (EXP != CURVE_SUCCESS) { \ 17 | return VOPRF_CURVE_OPERATION_ERROR; \ 18 | } 19 | 20 | static enum voprf_error blind( 21 | struct voprf* voprf, 22 | unsigned char* blinded_element, 23 | size_t blinded_element_len, 24 | unsigned char* blinding_factor, 25 | size_t blinding_factor_len, 26 | const unsigned char* input, 27 | size_t input_len) { 28 | size_t element_bytes = voprf->curve->element_bytes; 29 | size_t scalar_bytes = voprf->curve->scalar_bytes; 30 | if (blinded_element_len != element_bytes || 31 | blinding_factor_len != scalar_bytes) { 32 | return VOPRF_BUFFER_LENGTH_ERROR; 33 | } 34 | 35 | // Sample random blinding factor 36 | CURVE_SUCCESS_CHECK( 37 | voprf->curve->scalar_random(blinding_factor, blinding_factor_len)); 38 | 39 | unsigned char blinding_factor_point[element_bytes]; 40 | unsigned char hashed_message_point[element_bytes]; 41 | 42 | // Hash and blind input 43 | CURVE_SUCCESS_CHECK(voprf->curve->group_exp_generator( 44 | blinding_factor_point, 45 | element_bytes, 46 | blinding_factor, 47 | blinding_factor_len)); 48 | CURVE_SUCCESS_CHECK(voprf->curve->hash_to_curve( 49 | hashed_message_point, 50 | (const unsigned char*[]){input}, 51 | (const size_t[]){input_len}, 52 | 1)); 53 | CURVE_SUCCESS_CHECK(voprf->curve->group_op( 54 | blinded_element, 55 | blinded_element_len, 56 | hashed_message_point, 57 | element_bytes, 58 | blinding_factor_point, 59 | element_bytes)); 60 | return VOPRF_SUCCESS; 61 | } 62 | 63 | static enum voprf_error verifiable_unblind( 64 | struct voprf* voprf, 65 | unsigned char* unblinded_element, 66 | size_t unblinded_element_len, 67 | const unsigned char* proof_c, 68 | size_t proof_c_len, 69 | const unsigned char* proof_s, 70 | size_t proof_s_len, 71 | const unsigned char* blinding_factor, 72 | size_t blinding_factor_len, 73 | const unsigned char* evaluated_element, 74 | size_t evaluated_element_len, 75 | const unsigned char* blinded_element, 76 | size_t blinded_element_len, 77 | const unsigned char* pk, 78 | size_t pk_len, 79 | int flag_proof_verify) { 80 | size_t element_bytes = voprf->curve->element_bytes; 81 | size_t scalar_bytes = voprf->curve->scalar_bytes; 82 | if (unblinded_element_len != element_bytes || 83 | blinding_factor_len != scalar_bytes || 84 | evaluated_element_len != element_bytes || 85 | blinded_element_len != element_bytes || pk_len != element_bytes) { 86 | return VOPRF_BUFFER_LENGTH_ERROR; 87 | } 88 | CURVE_SUCCESS_CHECK( 89 | voprf->curve->check_on_curve(evaluated_element, evaluated_element_len)); 90 | CURVE_SUCCESS_CHECK( 91 | voprf->curve->check_on_curve(blinded_element, blinded_element_len)); 92 | 93 | // Verify proof 94 | if (flag_proof_verify) { 95 | if (proof_c == NULL || proof_s == NULL) { 96 | return VOPRF_PROOF_ERROR; 97 | } 98 | if (proof_c_len != scalar_bytes || proof_s_len != scalar_bytes) { 99 | return VOPRF_BUFFER_LENGTH_ERROR; 100 | } 101 | const size_t generator_len = voprf->curve->element_bytes; 102 | unsigned char generator[generator_len]; 103 | CURVE_SUCCESS_CHECK(voprf->curve->get_generator(generator, generator_len)); 104 | dleqproof_protocol_t dleqproof; 105 | dleqproof_init(&dleqproof, voprf->curve); 106 | if (dleqproof.verify( 107 | &dleqproof, 108 | proof_c, 109 | proof_c_len, 110 | proof_s, 111 | proof_s_len, 112 | generator, 113 | generator_len, 114 | blinded_element, 115 | blinded_element_len, 116 | pk, 117 | pk_len, 118 | evaluated_element, 119 | evaluated_element_len) != DLEQPROOF_SUCCESS) { 120 | return VOPRF_PROOF_ERROR; 121 | } 122 | } 123 | 124 | // Unblind evaluation 125 | unsigned char cancellation_point[element_bytes]; 126 | CURVE_SUCCESS_CHECK(voprf->curve->group_exp( 127 | cancellation_point, 128 | element_bytes, 129 | blinding_factor, 130 | blinded_element_len, 131 | pk, 132 | pk_len)); 133 | CURVE_SUCCESS_CHECK(voprf->curve->group_inv_op( 134 | unblinded_element, 135 | unblinded_element_len, 136 | evaluated_element, 137 | evaluated_element_len, 138 | cancellation_point, 139 | element_bytes)); 140 | return VOPRF_SUCCESS; 141 | } 142 | 143 | void voprf_mul_twohashdh_init(voprf_t* voprf, curve_t* curve) { 144 | voprf->final_evaluation_bytes = crypto_hash_sha512_BYTES; 145 | voprf->curve = curve; 146 | voprf->setup = setup; 147 | voprf->blind = blind; 148 | voprf->evaluate = evaluate; 149 | voprf->verifiable_unblind = verifiable_unblind; 150 | voprf->client_finalize = client_finalize; 151 | voprf->server_finalize = server_finalize; 152 | } 153 | -------------------------------------------------------------------------------- /src/crypto/voprf/voprf_twohashdh.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | 10 | #include "src/crypto/curve/curve.h" 11 | #include "src/crypto/dleqproof/dleqproof.h" 12 | #include "src/crypto/voprf/voprf.h" 13 | #include "src/crypto/voprf/voprf_twohashdh.h" 14 | 15 | #define CURVE_SUCCESS_CHECK(EXP) \ 16 | if (EXP != CURVE_SUCCESS) { \ 17 | return VOPRF_CURVE_OPERATION_ERROR; \ 18 | } 19 | 20 | enum voprf_error setup( 21 | voprf_t* voprf, 22 | unsigned char* sk, 23 | size_t sk_len, 24 | unsigned char* pk, 25 | size_t pk_len) { 26 | size_t element_bytes = voprf->curve->element_bytes; 27 | size_t scalar_bytes = voprf->curve->scalar_bytes; 28 | if (sk_len != scalar_bytes || pk_len != element_bytes) { 29 | return VOPRF_BUFFER_LENGTH_ERROR; 30 | } 31 | CURVE_SUCCESS_CHECK(voprf->curve->scalar_random(sk, sk_len)); 32 | CURVE_SUCCESS_CHECK( 33 | voprf->curve->group_exp_generator(pk, pk_len, sk, sk_len)); 34 | return VOPRF_SUCCESS; 35 | } 36 | 37 | enum voprf_error evaluate( 38 | voprf_t* voprf, 39 | unsigned char* evaluated_element, 40 | size_t evaluated_element_len, 41 | unsigned char* proof_c, 42 | size_t proof_c_len, 43 | unsigned char* proof_s, 44 | size_t proof_s_len, 45 | const unsigned char* sk, 46 | size_t sk_len, 47 | const unsigned char* blinded_element, 48 | size_t blinded_element_len, 49 | int flag_proof_generate) { 50 | size_t element_bytes = voprf->curve->element_bytes; 51 | size_t scalar_bytes = voprf->curve->scalar_bytes; 52 | if (evaluated_element_len != element_bytes || sk_len != scalar_bytes || 53 | blinded_element_len != element_bytes) { 54 | return VOPRF_BUFFER_LENGTH_ERROR; 55 | } 56 | CURVE_SUCCESS_CHECK( 57 | voprf->curve->check_on_curve(blinded_element, blinded_element_len)); 58 | // Perform evaluation 59 | CURVE_SUCCESS_CHECK(voprf->curve->group_exp( 60 | evaluated_element, 61 | evaluated_element_len, 62 | sk, 63 | sk_len, 64 | blinded_element, 65 | blinded_element_len)); 66 | if (flag_proof_generate) { 67 | if (proof_c == NULL || proof_s == NULL) { 68 | return VOPRF_PROOF_ERROR; 69 | } 70 | if (proof_c_len != scalar_bytes || proof_s_len != scalar_bytes) { 71 | return VOPRF_BUFFER_LENGTH_ERROR; 72 | } 73 | size_t generator_len = element_bytes; 74 | unsigned char generator[generator_len]; 75 | CURVE_SUCCESS_CHECK(voprf->curve->get_generator(generator, element_bytes)); 76 | size_t pk_len = element_bytes; 77 | unsigned char pk[pk_len]; 78 | CURVE_SUCCESS_CHECK( 79 | voprf->curve->group_exp_generator(pk, element_bytes, sk, scalar_bytes)); 80 | dleqproof_protocol_t dleqproof; 81 | dleqproof_init(&dleqproof, voprf->curve); 82 | if (dleqproof.prove( 83 | &dleqproof, 84 | proof_c, 85 | proof_c_len, 86 | proof_s, 87 | proof_s_len, 88 | generator, 89 | generator_len, 90 | blinded_element, 91 | blinded_element_len, 92 | pk, 93 | pk_len, 94 | evaluated_element, 95 | evaluated_element_len, 96 | sk, 97 | sk_len) != CURVE_SUCCESS) { 98 | return VOPRF_PROOF_ERROR; 99 | } 100 | } 101 | 102 | return VOPRF_SUCCESS; 103 | } 104 | 105 | static enum voprf_error hash_final_evaluation( 106 | struct voprf* voprf, 107 | unsigned char* final_evaluation, 108 | const unsigned char* input, 109 | size_t input_len, 110 | const unsigned char* evaluation_element) { 111 | // TODO: Use indifferentiable hash function 112 | size_t element_len = voprf->curve->element_bytes; 113 | 114 | crypto_hash_sha512_state state; 115 | if (crypto_hash_sha512_init(&state) != CURVE_SUCCESS) { 116 | return VOPRF_HASH_OPERATION_ERROR; 117 | } 118 | if (crypto_hash_sha512_update(&state, input, input_len) != CURVE_SUCCESS) { 119 | return VOPRF_HASH_OPERATION_ERROR; 120 | } 121 | if (crypto_hash_sha512_update(&state, evaluation_element, element_len) != 122 | CURVE_SUCCESS) { 123 | return VOPRF_HASH_OPERATION_ERROR; 124 | } 125 | if (crypto_hash_sha512_final(&state, final_evaluation) != CURVE_SUCCESS) { 126 | return VOPRF_HASH_OPERATION_ERROR; 127 | } 128 | 129 | return VOPRF_SUCCESS; 130 | } 131 | 132 | enum voprf_error client_finalize( 133 | voprf_t* voprf, 134 | unsigned char* final_evaluation, 135 | size_t final_evaluation_len, 136 | const unsigned char* input, 137 | size_t input_len, 138 | const unsigned char* unblinded_element, 139 | size_t unblinded_element_len) { 140 | size_t element_bytes = voprf->curve->element_bytes; 141 | size_t final_evaluation_bytes = voprf->final_evaluation_bytes; 142 | if (final_evaluation_len != final_evaluation_bytes || 143 | unblinded_element_len != element_bytes) { 144 | return VOPRF_BUFFER_LENGTH_ERROR; 145 | } 146 | return hash_final_evaluation( 147 | voprf, final_evaluation, input, input_len, unblinded_element); 148 | } 149 | 150 | enum voprf_error server_finalize( 151 | voprf_t* voprf, 152 | unsigned char* final_evaluation, 153 | size_t final_evaluation_len, 154 | const unsigned char* input, 155 | size_t input_len, 156 | const unsigned char* sk, 157 | size_t sk_len) { 158 | size_t element_bytes = voprf->curve->element_bytes; 159 | size_t scalar_bytes = voprf->curve->scalar_bytes; 160 | size_t final_evaluation_bytes = voprf->final_evaluation_bytes; 161 | if (final_evaluation_len != final_evaluation_bytes || 162 | sk_len != scalar_bytes) { 163 | return VOPRF_BUFFER_LENGTH_ERROR; 164 | } 165 | unsigned char hashed_message[element_bytes]; 166 | unsigned char evaluation_element[element_bytes]; 167 | CURVE_SUCCESS_CHECK(voprf->curve->hash_to_curve( 168 | hashed_message, 169 | (const unsigned char*[]){input}, 170 | (const size_t[]){input_len}, 171 | 1)); 172 | CURVE_SUCCESS_CHECK(voprf->curve->group_exp( 173 | evaluation_element, 174 | element_bytes, 175 | sk, 176 | sk_len, 177 | hashed_message, 178 | element_bytes)); 179 | return hash_final_evaluation( 180 | voprf, final_evaluation, input, input_len, evaluation_element); 181 | } 182 | -------------------------------------------------------------------------------- /src/service/SimpleAnonCredServiceHandler.cpp: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include "demo/SimpleAnonCredServiceHandler.h" 9 | #include 10 | #include "demo/SimpleAnonCredUtils.h" 11 | 12 | namespace anon_cred { 13 | 14 | using namespace thrift; 15 | 16 | SimpleAnonCredServiceHandler::SimpleAnonCredServiceHandler() { 17 | curve_ristretto_init(&curve_); 18 | voprf_mul_twohashdh_init(&voprf_, &curve_); 19 | kdf_sdhi_init(&kdf_, &curve_); 20 | auto primayKeyBytes = kdf_.primary_key_bytes; 21 | primaryKey_.resize(primayKeyBytes); 22 | kdf_.generate_primary_key(&kdf_, primaryKey_.data(), primayKeyBytes); 23 | std::cout << "Generated primary key: " << util::binToHex(primaryKey_) 24 | << std::endl; 25 | } 26 | void SimpleAnonCredServiceHandler::getPrimaryPublicKey( 27 | GetPrimaryPublicKeyResponse& response) { 28 | std::vector primaryPublicKey(kdf_.primary_private_key_bytes); 29 | kdf_.derive_primary_public_key( 30 | &kdf_, 31 | primaryPublicKey.data(), 32 | primaryPublicKey.size(), 33 | primaryKey_.data(), 34 | primaryKey_.size()); 35 | response.primay_public_key = util::binToHex(primaryPublicKey); 36 | std::cout << "Primary public key: " << util::binToHex(primaryPublicKey) 37 | << std::endl; 38 | } 39 | 40 | void SimpleAnonCredServiceHandler::getPublicKeyAndProof( 41 | GetPublicKeyResponse& response, 42 | const GetPublicKeyRequest& request) { 43 | std::vector pk, sk, pkProof; 44 | deriveKeyPair(sk, pk, pkProof, request.attributes); 45 | response.public_key = util::binToHex(pk); 46 | response.public_key_proof = util::binToHex(pkProof); 47 | 48 | std::cout << "Public key: " << util::binToHex(pk) << std::endl; 49 | std::cout << "Public key proof: " << util::binToHex(pkProof) << std::endl; 50 | } 51 | 52 | void SimpleAnonCredServiceHandler::signCredential( 53 | SignCredentialResponse& response, 54 | const SignCredentialRequest& request) { 55 | auto elementBytes = curve_.element_bytes; 56 | auto scalarBytes = curve_.scalar_bytes; 57 | std::vector pk, sk, pkProof; 58 | deriveKeyPair(sk, pk, pkProof, request.attributes); 59 | auto blindedElement = 60 | util::hexToBin(request.blinded_token, request.blinded_token.size() / 2); 61 | std::vector blindedSignature(elementBytes); 62 | std::vector proofC(scalarBytes); 63 | std::vector proofS(scalarBytes); 64 | auto evaluateErrorcode = voprf_.evaluate( 65 | &voprf_, 66 | blindedSignature.data(), 67 | blindedSignature.size(), 68 | proofC.data(), 69 | proofC.size(), 70 | proofS.data(), 71 | proofS.size(), 72 | sk.data(), 73 | sk.size(), 74 | blindedElement.data(), 75 | blindedElement.size(), 76 | 1); 77 | if (evaluateErrorcode != VOPRF_SUCCESS) { 78 | VoprfErrorException exception; 79 | exception.errorcode = evaluateErrorcode; 80 | exception.message = "signCredential throws voprf_error, see voprf.h"; 81 | throw exception; 82 | } 83 | 84 | response.evaluated_token = util::binToHex(blindedSignature); 85 | response.proof_c = util::binToHex(proofC); 86 | response.proof_s = util::binToHex(proofS); 87 | 88 | std::cout << "Blinded token: " << request.blinded_token << std::endl; 89 | std::cout << "Evaluated token: " << response.evaluated_token << std::endl; 90 | std::cout << "Proof.c: " << response.proof_c << std::endl; 91 | std::cout << "Proof.s: " << response.proof_s << std::endl; 92 | } 93 | 94 | // TODO: Add check for token expiration and reuse limit 95 | void SimpleAnonCredServiceHandler::redeemCredential( 96 | const RedeemCredentialRequest& request) { 97 | auto elementBytes = curve_.element_bytes; 98 | auto scalarBytes = curve_.scalar_bytes; 99 | std::vector pk, sk, pkProof; 100 | deriveKeyPair(sk, pk, pkProof, request.attributes); 101 | auto finalEvaluationBytes = voprf_.final_evaluation_bytes; 102 | std::vector finalEvaluation(finalEvaluationBytes); 103 | auto serverFinalizeErrorcode = voprf_.server_finalize( 104 | &voprf_, 105 | finalEvaluation.data(), 106 | finalEvaluation.size(), 107 | (const unsigned char*)request.token.data(), 108 | request.token.size(), 109 | sk.data(), 110 | sk.size()); 111 | if (serverFinalizeErrorcode != VOPRF_SUCCESS) { 112 | VoprfErrorException exception; 113 | exception.errorcode = serverFinalizeErrorcode; 114 | exception.message = "redeemCredential throws voprf_error, see voprf.h"; 115 | throw exception; 116 | } 117 | std::cout << "Server secret: " << util::binToHex(finalEvaluation) 118 | << std::endl; 119 | std::cout << "Client secret: " << request.shared_secret << std::endl; 120 | auto clientEvaluation = 121 | util::hexToBin(request.shared_secret, finalEvaluationBytes); 122 | if (sodium_memcmp( 123 | clientEvaluation.data(), 124 | finalEvaluation.data(), 125 | finalEvaluationBytes) != 0) { 126 | CredentialMismatchException exception; 127 | exception.message = 128 | "Secrets mismatch, client secret: " + request.shared_secret; 129 | throw exception; 130 | } 131 | std::cout << "Redeem credential success!" << std::endl; 132 | } 133 | 134 | void SimpleAnonCredServiceHandler::deriveKeyPair( 135 | std::vector& sk, 136 | std::vector& pk, 137 | std::vector& pkProof, 138 | const std::vector& attributes) { 139 | auto elementBytes = curve_.element_bytes; 140 | auto scalarBytes = curve_.scalar_bytes; 141 | auto pkProofBytes = kdf_.public_key_proof_bytes; 142 | sk.resize(scalarBytes); 143 | pk.resize(elementBytes); 144 | pkProof.resize(pkProofBytes); 145 | auto attributeArrSize = attributes.size(); 146 | std::vector attributeArr; 147 | std::vector attributeLenArr; 148 | for (const std::string& s : attributes) { 149 | attributeLenArr.push_back(s.size()); 150 | attributeArr.push_back((const unsigned char*)s.data()); 151 | } 152 | kdf_.derive_key_pair( 153 | &kdf_, 154 | sk.data(), 155 | sk.size(), 156 | pk.data(), 157 | pk.size(), 158 | pkProof.data(), 159 | pkProof.size(), 160 | primaryKey_.data(), 161 | primaryKey_.size(), 162 | attributeArrSize, 163 | attributeArr.data(), 164 | attributeLenArr.data(), 165 | 1); 166 | } 167 | 168 | } // namespace anon_cred 169 | -------------------------------------------------------------------------------- /tests/dleqproof_test.cpp: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | #include 10 | #include 11 | extern "C" { 12 | #include "src/crypto/curve/curve.h" 13 | #include "src/crypto/curve/curve_ed25519.h" 14 | #include "src/crypto/curve/curve_ristretto.h" 15 | #include "src/crypto/dleqproof/dleqproof.h" 16 | } 17 | 18 | namespace { 19 | 20 | enum class CryptoCurve { 21 | CURVE_RISTRETTO, 22 | CURVE_ED25519, 23 | }; 24 | 25 | struct DleqproofTest : public testing::TestWithParam { 26 | void SetUp() override { 27 | switch (GetParam()) { 28 | case CryptoCurve::CURVE_ED25519: 29 | curve_ed25519_init(&curve_); 30 | break; 31 | case CryptoCurve::CURVE_RISTRETTO: 32 | curve_ristretto_init(&curve_); 33 | break; 34 | } 35 | dleqproof_init(&protocol_, &curve_); 36 | } 37 | 38 | void TearDown() override {} 39 | 40 | curve_t curve_; 41 | dleqproof_protocol_t protocol_; 42 | }; 43 | 44 | TEST_P(DleqproofTest, ProveAndVerifyTest) { 45 | unsigned char x1[curve_.scalar_bytes]; 46 | unsigned char x2[curve_.scalar_bytes]; 47 | unsigned char base1[curve_.element_bytes]; 48 | unsigned char base2[curve_.element_bytes]; 49 | unsigned char element1[curve_.element_bytes]; 50 | unsigned char element2[curve_.element_bytes]; 51 | unsigned char proof_c[curve_.scalar_bytes]; 52 | unsigned char proof_s[curve_.scalar_bytes]; 53 | 54 | curve_.scalar_random(x1, curve_.scalar_bytes); 55 | curve_.scalar_random(x2, curve_.scalar_bytes); 56 | curve_.get_generator(base1, curve_.element_bytes); 57 | 58 | // initialize base2 and make it on curve 59 | unsigned char* token = (unsigned char*)"test"; 60 | const size_t token_len = 4; 61 | curve_.hash_to_curve( 62 | base2, (const unsigned char*[]){token}, (const size_t[]){token_len}, 1); 63 | 64 | curve_.group_exp( 65 | element1, 66 | curve_.element_bytes, 67 | x1, 68 | curve_.scalar_bytes, 69 | base1, 70 | curve_.element_bytes); 71 | curve_.group_exp( 72 | element2, 73 | curve_.element_bytes, 74 | x1, 75 | curve_.scalar_bytes, 76 | base2, 77 | curve_.element_bytes); 78 | 79 | // Prove and verify 80 | EXPECT_EQ( 81 | protocol_.prove( 82 | &protocol_, 83 | proof_c, 84 | curve_.scalar_bytes, 85 | proof_s, 86 | curve_.scalar_bytes, 87 | base1, 88 | curve_.element_bytes, 89 | base2, 90 | curve_.element_bytes, 91 | element1, 92 | curve_.element_bytes, 93 | element2, 94 | curve_.element_bytes, 95 | x1, 96 | curve_.scalar_bytes), 97 | DLEQPROOF_SUCCESS); 98 | EXPECT_EQ( 99 | protocol_.verify( 100 | &protocol_, 101 | proof_c, 102 | curve_.scalar_bytes, 103 | proof_s, 104 | curve_.scalar_bytes, 105 | base1, 106 | curve_.element_bytes, 107 | base2, 108 | curve_.element_bytes, 109 | element1, 110 | curve_.element_bytes, 111 | element2, 112 | curve_.element_bytes), 113 | DLEQPROOF_SUCCESS); 114 | 115 | // Fail to verify by providing different discrete log 116 | EXPECT_EQ( 117 | protocol_.prove( 118 | &protocol_, 119 | proof_c, 120 | curve_.scalar_bytes, 121 | proof_s, 122 | curve_.scalar_bytes, 123 | base1, 124 | curve_.element_bytes, 125 | base2, 126 | curve_.element_bytes, 127 | element1, 128 | curve_.element_bytes, 129 | element2, 130 | curve_.element_bytes, 131 | x2, 132 | curve_.scalar_bytes), 133 | DLEQPROOF_SUCCESS); 134 | EXPECT_EQ( 135 | protocol_.verify( 136 | &protocol_, 137 | proof_c, 138 | curve_.scalar_bytes, 139 | proof_s, 140 | curve_.scalar_bytes, 141 | base1, 142 | curve_.element_bytes, 143 | base2, 144 | curve_.element_bytes, 145 | element1, 146 | curve_.element_bytes, 147 | element2, 148 | curve_.element_bytes), 149 | DLEQPROOF_VERIFY_FAIL); 150 | 151 | // Fail to verify by providing wrong base 152 | EXPECT_EQ( 153 | protocol_.prove( 154 | &protocol_, 155 | proof_c, 156 | curve_.scalar_bytes, 157 | proof_s, 158 | curve_.scalar_bytes, 159 | base2, 160 | curve_.element_bytes, 161 | base2, 162 | curve_.element_bytes, 163 | element1, 164 | curve_.element_bytes, 165 | element2, 166 | curve_.element_bytes, 167 | x1, 168 | curve_.scalar_bytes), 169 | DLEQPROOF_SUCCESS); 170 | EXPECT_EQ( 171 | protocol_.verify( 172 | &protocol_, 173 | proof_c, 174 | curve_.scalar_bytes, 175 | proof_s, 176 | curve_.scalar_bytes, 177 | base1, 178 | curve_.element_bytes, 179 | base2, 180 | curve_.element_bytes, 181 | element1, 182 | curve_.element_bytes, 183 | element2, 184 | curve_.element_bytes), 185 | DLEQPROOF_VERIFY_FAIL); 186 | } 187 | 188 | TEST_P(DleqproofTest, NotOnCurveTest) { 189 | unsigned char x[curve_.scalar_bytes]; 190 | unsigned char base1[curve_.element_bytes]; 191 | unsigned char base2[curve_.element_bytes]; 192 | unsigned char proof_c[curve_.scalar_bytes]; 193 | unsigned char proof_s[curve_.scalar_bytes]; 194 | unsigned char element1[curve_.element_bytes]; 195 | unsigned char element2[curve_.element_bytes]; 196 | 197 | curve_.scalar_random(x, curve_.scalar_bytes); 198 | curve_.get_generator(base1, curve_.element_bytes); 199 | 200 | // initialize base2 and make it not on curve 201 | char h[] = "cd10942ca1885798e1987b43b068f9b8f344576b44f570a5debf734949210960"; 202 | sodium_hex2bin(base2, curve_.element_bytes, h, strlen(h), NULL, NULL, NULL); 203 | 204 | curve_.group_exp( 205 | element1, 206 | curve_.element_bytes, 207 | x, 208 | curve_.scalar_bytes, 209 | base1, 210 | curve_.element_bytes); 211 | curve_.group_exp( 212 | element2, 213 | curve_.element_bytes, 214 | x, 215 | curve_.scalar_bytes, 216 | base2, 217 | curve_.element_bytes); 218 | 219 | EXPECT_EQ( 220 | protocol_.prove( 221 | &protocol_, 222 | proof_c, 223 | curve_.scalar_bytes, 224 | proof_s, 225 | curve_.scalar_bytes, 226 | base1, 227 | curve_.element_bytes, 228 | base2, 229 | curve_.element_bytes, 230 | element1, 231 | curve_.element_bytes, 232 | element2, 233 | curve_.element_bytes, 234 | x, 235 | curve_.scalar_bytes), 236 | DLEQPROOF_CURVE_OPERATION_ERROR); 237 | } 238 | 239 | INSTANTIATE_TEST_SUITE_P( 240 | VOPRFLib, 241 | DleqproofTest, 242 | testing::Values(CryptoCurve::CURVE_ED25519, CryptoCurve::CURVE_RISTRETTO)); 243 | 244 | } // namespace 245 | -------------------------------------------------------------------------------- /src/crypto/kdf/kdf.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #pragma once 9 | 10 | #include 11 | 12 | #include "src/crypto/curve/curve.h" 13 | 14 | enum kdf_error { 15 | KDF_SUCCESS = 0, 16 | KDF_UNKNOWN_ERROR = -1, 17 | KDF_BUFFER_LENGTH_ERROR = 1, 18 | KDF_CURVE_OPERATION_ERROR = 2, 19 | KDF_PK_PROOF_ERROR = 3, 20 | }; 21 | 22 | /** 23 | * Key derivation function (KDF) is used to derive general private and public 24 | * key pairs for VOPRF evaluate (sign) and finalize (redeem). For some KDFs, an 25 | * optional “public key proof” (pk_proof) can be generated. The proof can be 26 | * verified (by verify_attr_public_key) by the client to improve key 27 | * transparency. 28 | */ 29 | 30 | typedef struct kdf kdf_t; 31 | 32 | struct kdf { 33 | /** 34 | * The size of the primary key. 35 | */ 36 | size_t primary_key_bytes; 37 | 38 | /** 39 | * The size of the primary public key. (0 if the KDF does not support public 40 | * key proof) 41 | */ 42 | size_t primary_public_key_bytes; 43 | 44 | /** 45 | * The size of the primary private key. 46 | */ 47 | size_t primary_private_key_bytes; 48 | 49 | /** 50 | * The size of the public key proof. (0 if the KDF does not support public 51 | * key proof) 52 | */ 53 | size_t public_key_proof_bytes; 54 | 55 | /** 56 | * The elliptic curve used in this KDF. 57 | */ 58 | curve_t* curve; 59 | 60 | /** 61 | * Generated a random primary key. Some KDFs’ primary keys contain “private” 62 | * and “public” part, i.e. primary private key and primary public key. Some 63 | * KDFs’ primary keys only contain a single secret. 64 | * 65 | * @param kdf A pointer to kdf struct. 66 | * @param primary_key Mutable unsigned char buffers for output. 67 | * @param primary_key_len The size of this buffer should be primary_key_bytes 68 | * of the kdf. 69 | */ 70 | enum kdf_error (*generate_primary_key)( 71 | kdf_t* /* kdf */, 72 | unsigned char* /* primary_key */, 73 | size_t /* primary_key_len */); 74 | 75 | /** 76 | * Derive primary public key from primary key. 77 | * Client can use this primary public key to verify the public key generated 78 | * from derive_primary_public_key(). 79 | * Note: some KDFs may not support public key verification. For those KDFs, 80 | * this method will do nothing and return KDF_SUCCESS directly. 81 | * 82 | * @param kdf A pointer to kdf struct. 83 | * @param ppk Mutable unsigned char buffers for primary public key. 84 | * @param ppk_len The size of this buffer should be primary_public_key_bytes 85 | * of the KDF. 86 | * @param primary_key Immutable unsigned char buffers for primary key. 87 | * @param primary_key_len The size of these buffers should be 88 | * primary_key_bytes of the curve. 89 | */ 90 | enum kdf_error (*derive_primary_public_key)( 91 | kdf_t* /* kdf */, 92 | unsigned char* /* ppk */, 93 | size_t /* ppk_len */, 94 | const unsigned char* /* primary_key */, 95 | size_t /* primary_key_len */ 96 | ); 97 | 98 | /** 99 | * Derive private key and public key from primary key and some attribute 100 | * strings. This private and public key pair can be used for VOPRF operations. 101 | * Optionally, generate a public key proof for clients to verify the public 102 | * key (with primary public key and attribute strings). 103 | * Note: some KDFs may not support public key verification. For those KDFs, 104 | * this method will ignore the parameter pk_proof and flag_pk_proof_generate. 105 | * 106 | * @param kdf A pointer to kdf struct. 107 | * @param sk Mutable unsigned char buffer for private key. 108 | * @param sk_len The size of this buffer should be scalar_bytes of the curve. 109 | * @param pk Mutable unsigned char buffer for public key. 110 | * @param pk_len The size of this buffer should be element_bytes of the curve. 111 | * @param pk_proof Mutable unsigned char buffer for public key proof. This is 112 | * optional if flag_pk_proof_generate = 0. 113 | * @param pk_proof_len The size of this buffer should be 114 | * public_key_proof_bytes of the kdf. This is optional if 115 | * flag_pk_proof_generate = 0. 116 | * @param primary_key Unsigned char buffer for primary key. 117 | * @param primary_key_len The size of this buffer should be primary_key_bytes 118 | * of the curve. 119 | * @param n_attributes Number of elements in attribute array 120 | * @param attribute_arr A pointer to an array, storing pointers to unsigned 121 | * char buffers. The size of the array should be n_attributes. 122 | * @param attribute_len_array A pointer to an array, storing the length of the 123 | * unsigned char buffer corresponding to the same index of attribute_arr.The 124 | * size of the array should be n_attributes. 125 | * @param flag_pk_proof_generate Use flag_pk_proof_generate = 1 if pk_proof is 126 | * needed, 0 otherwise. 127 | */ 128 | enum kdf_error (*derive_key_pair)( 129 | kdf_t* /* kdf */, 130 | unsigned char* /* sk */, 131 | size_t /* sk_len */, 132 | unsigned char* /* pk */, 133 | size_t /* pk_len */, 134 | unsigned char* /* pk_proof */, 135 | size_t /* pk_proof_len */, 136 | const unsigned char* /* primary_key */, 137 | size_t /* primary_key_len */, 138 | int /* n_attributes */, 139 | const unsigned char** /* attribute_arr */, 140 | const size_t* /* attribute_len_arr */, 141 | int /* flag_pk_proof_generate */); 142 | 143 | /** 144 | * (Client side) Verify the public key received with public key proof and 145 | * primary public key. 146 | * Note: some KDFs may not support public key verification. For those KDFs, 147 | * this method will do nothing and return KDF_SUCCESS directly. 148 | * 149 | * @param kdf A pointer to kdf struct. 150 | * @param pk Unsigned char buffer for public key. 151 | * @param pk_len The size of this buffer should be element_bytes of the curve. 152 | * @param pk_proof Unsigned char buffer for public key proof. 153 | * @param pk_proof_len The size of this buffer should be 154 | * public_key_proof_bytes of the kdf. 155 | * @param ppk Unsigned char buffer for primary public key. 156 | * @param ppk_len The size of this buffer should be primary_public_key_bytes 157 | * of the curve. 158 | * @param n_attributes Number of elements in attribute array 159 | * @param attribute_arr A pointer to an array, storing pointers to unsigned 160 | * char buffers. The size of the array should be n_attributes. 161 | * @param attribute_len_array A pointer to an array, storing the length of the 162 | * unsigned char buffer corresponding to the same index of attribute_arr.The 163 | * size of the array should be n_attributes. 164 | */ 165 | enum kdf_error (*verify_public_key)( 166 | kdf_t* /* kdf */, 167 | const unsigned char* /* pk */, 168 | size_t /* pk_len */, 169 | const unsigned char* /* pk_proof */, 170 | size_t /* pk_proof_len */, 171 | const unsigned char* /* ppk */, 172 | size_t /* ppk_len */, 173 | int /* n_attributes */, 174 | const unsigned char** /* attribute_arr */, 175 | const size_t* /* attribute_len_arr */); 176 | }; 177 | -------------------------------------------------------------------------------- /src/crypto/kdf/kdf_sdhi.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | #include 10 | 11 | #include "src/crypto/curve/curve.h" 12 | #include "src/crypto/dleqproof/dleqproof.h" 13 | #include "src/crypto/kdf/kdf.h" 14 | #include "src/crypto/kdf/kdf_sdhi.h" 15 | 16 | #define CURVE_SUCCESS_CHECK(EXP) \ 17 | if (EXP != CURVE_SUCCESS) { \ 18 | return KDF_CURVE_OPERATION_ERROR; \ 19 | } 20 | 21 | static enum kdf_error generate_primary_key( 22 | kdf_t* kdf, 23 | unsigned char* primary_key, 24 | size_t primary_key_len) { 25 | size_t element_bytes = kdf->curve->element_bytes; 26 | size_t scalar_bytes = kdf->curve->scalar_bytes; 27 | if (primary_key_len != kdf->primary_key_bytes) { 28 | return KDF_BUFFER_LENGTH_ERROR; 29 | } 30 | CURVE_SUCCESS_CHECK(kdf->curve->scalar_random(primary_key, scalar_bytes)); 31 | CURVE_SUCCESS_CHECK(kdf->curve->group_exp_generator( 32 | primary_key + kdf->primary_private_key_bytes, 33 | element_bytes, 34 | primary_key, 35 | scalar_bytes)); 36 | return KDF_SUCCESS; 37 | } 38 | 39 | static enum kdf_error derive_key_pair( 40 | kdf_t* kdf, 41 | unsigned char* sk, 42 | size_t sk_len, 43 | unsigned char* pk, 44 | size_t pk_len, 45 | unsigned char* pk_proof, 46 | size_t pk_proof_len, 47 | const unsigned char* primary_key, 48 | size_t primary_key_len, 49 | int n_attributes, 50 | const unsigned char** attribute_arr, 51 | const size_t* attribute_len_arr, 52 | int flag_pk_proof_generate) { 53 | const size_t scalar_bytes = kdf->curve->scalar_bytes; 54 | const size_t element_bytes = kdf->curve->element_bytes; 55 | 56 | if (sk_len != scalar_bytes || pk_len != element_bytes || 57 | primary_key_len != kdf->primary_key_bytes) { 58 | return KDF_BUFFER_LENGTH_ERROR; 59 | } 60 | 61 | const unsigned char* primary_private_key_ptr = primary_key; 62 | 63 | // Hash attribute to scalar 64 | unsigned char attr_hash[scalar_bytes]; 65 | CURVE_SUCCESS_CHECK(kdf->curve->hash_to_scalar( 66 | attr_hash, attribute_arr, attribute_len_arr, n_attributes)); 67 | 68 | unsigned char tmp_inverse[scalar_bytes]; 69 | CURVE_SUCCESS_CHECK(kdf->curve->scalar_add( 70 | tmp_inverse, 71 | scalar_bytes, 72 | primary_private_key_ptr, 73 | kdf->primary_private_key_bytes, 74 | attr_hash, 75 | scalar_bytes)); 76 | CURVE_SUCCESS_CHECK( 77 | kdf->curve->scalar_inv(sk, scalar_bytes, tmp_inverse, scalar_bytes)); 78 | CURVE_SUCCESS_CHECK(kdf->curve->group_exp_generator(pk, pk_len, sk, sk_len)); 79 | 80 | if (flag_pk_proof_generate) { 81 | if (pk_proof == NULL) { 82 | return KDF_PK_PROOF_ERROR; 83 | } 84 | if (pk_proof_len != kdf->public_key_proof_bytes) { 85 | return KDF_BUFFER_LENGTH_ERROR; 86 | } 87 | unsigned char generator[element_bytes]; 88 | CURVE_SUCCESS_CHECK(kdf->curve->get_generator(generator, element_bytes)); 89 | 90 | unsigned char tmp_inverse_element[element_bytes]; 91 | CURVE_SUCCESS_CHECK(kdf->curve->group_exp_generator( 92 | tmp_inverse_element, element_bytes, tmp_inverse, scalar_bytes)); 93 | dleqproof_protocol_t dleqproof; 94 | dleqproof_init(&dleqproof, kdf->curve); 95 | if (dleqproof.prove( 96 | &dleqproof /* protocol */, 97 | pk_proof /* proof_c */, 98 | scalar_bytes, 99 | pk_proof + scalar_bytes /* proof_s */, 100 | scalar_bytes, 101 | generator /* base1 */, 102 | element_bytes, 103 | pk /* base2 */, 104 | pk_len, 105 | tmp_inverse_element /* element1 */, 106 | element_bytes, 107 | generator /* element2 */, 108 | element_bytes, 109 | tmp_inverse /* discrete_log */, 110 | scalar_bytes) != DLEQPROOF_SUCCESS) { 111 | return KDF_PK_PROOF_ERROR; 112 | } 113 | } 114 | sodium_memzero(tmp_inverse, scalar_bytes); 115 | return KDF_SUCCESS; 116 | } 117 | 118 | static enum kdf_error verify_public_key( 119 | kdf_t* kdf, 120 | const unsigned char* pk, 121 | size_t pk_len, 122 | const unsigned char* pk_proof, 123 | size_t pk_proof_len, 124 | const unsigned char* ppk, 125 | size_t ppk_len, 126 | int n_attributes, 127 | const unsigned char** attribute_arr, 128 | const size_t* attribute_len_arr) { 129 | size_t scalar_bytes = kdf->curve->scalar_bytes; 130 | size_t element_bytes = kdf->curve->element_bytes; 131 | if (pk_len != element_bytes || pk_proof_len != kdf->public_key_proof_bytes || 132 | ppk_len != kdf->primary_private_key_bytes) { 133 | return KDF_BUFFER_LENGTH_ERROR; 134 | } 135 | // Hash attribute to scalar 136 | unsigned char attr_hash[scalar_bytes]; 137 | CURVE_SUCCESS_CHECK(kdf->curve->hash_to_scalar( 138 | attr_hash, attribute_arr, attribute_len_arr, n_attributes)); 139 | 140 | unsigned char generator[element_bytes]; 141 | unsigned char tmp_attr_element[element_bytes]; 142 | unsigned char tmp_inverse_element[element_bytes]; 143 | CURVE_SUCCESS_CHECK(kdf->curve->get_generator(generator, element_bytes)); 144 | CURVE_SUCCESS_CHECK(kdf->curve->group_exp_generator( 145 | tmp_attr_element, element_bytes, attr_hash, scalar_bytes)); 146 | CURVE_SUCCESS_CHECK(kdf->curve->group_op( 147 | tmp_inverse_element, 148 | element_bytes, 149 | ppk, 150 | ppk_len, 151 | tmp_attr_element, 152 | element_bytes)); 153 | 154 | dleqproof_protocol_t dleqproof; 155 | dleqproof_init(&dleqproof, kdf->curve); 156 | return dleqproof.verify( 157 | &dleqproof /* protocol */, 158 | pk_proof /* proof_c */, 159 | scalar_bytes, 160 | pk_proof + scalar_bytes /* proof_s */, 161 | scalar_bytes, 162 | generator /* base1 */, 163 | element_bytes, 164 | pk /* base2 */, 165 | pk_len, 166 | tmp_inverse_element /* element1 */, 167 | element_bytes, 168 | generator /* element2 */, 169 | element_bytes) == DLEQPROOF_SUCCESS 170 | ? KDF_SUCCESS 171 | : KDF_PK_PROOF_ERROR; 172 | } 173 | 174 | static enum kdf_error derive_primary_public_key( 175 | kdf_t* kdf, 176 | unsigned char* ppk, 177 | size_t ppk_len, 178 | const unsigned char* primary_key, 179 | size_t primary_key_len) { 180 | if (ppk_len != kdf->primary_private_key_bytes || 181 | primary_key_len != kdf->primary_key_bytes) { 182 | return KDF_BUFFER_LENGTH_ERROR; 183 | } 184 | memcpy( 185 | ppk, 186 | primary_key + kdf->primary_private_key_bytes, 187 | kdf->primary_public_key_bytes); 188 | return KDF_SUCCESS; 189 | } 190 | 191 | void kdf_sdhi_init(kdf_t* kdf, curve_t* curve) { 192 | kdf->curve = curve; 193 | kdf->primary_private_key_bytes = curve->scalar_bytes; 194 | kdf->primary_public_key_bytes = curve->element_bytes; 195 | kdf->primary_key_bytes = curve->scalar_bytes + curve->element_bytes; 196 | kdf->public_key_proof_bytes = 2 * curve->scalar_bytes; 197 | kdf->generate_primary_key = generate_primary_key; 198 | kdf->derive_key_pair = derive_key_pair; 199 | kdf->verify_public_key = verify_public_key; 200 | kdf->derive_primary_public_key = derive_primary_public_key; 201 | } 202 | -------------------------------------------------------------------------------- /src/service/SimpleAnonCredClient.cpp: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include "demo/SimpleAnonCredClient.h" 9 | #include "demo/SimpleAnonCredUtils.h" 10 | 11 | namespace anon_cred { 12 | 13 | SimpleAnonCredClient::SimpleAnonCredClient( 14 | std::shared_ptr<::apache::thrift::protocol::TProtocol> prot) 15 | : thriftClient_(prot) { 16 | if (sodium_init() == -1) { 17 | throw std::runtime_error("sodium_init failed"); 18 | } 19 | curve_ristretto_init(&curve_); 20 | voprf_mul_twohashdh_init(&voprf_, &curve_); 21 | kdf_sdhi_init(&kdf_, &curve_); 22 | primaryPublicKey.resize(kdf_.primary_public_key_bytes); 23 | publicKey.resize(curve_.element_bytes); 24 | unBlindedElement.resize(curve_.element_bytes); 25 | } 26 | 27 | void SimpleAnonCredClient::getPrimaryPublicKey() { 28 | thrift::GetPrimaryPublicKeyResponse getPrimaryPublicKeyResp; 29 | thriftClient_.getPrimaryPublicKey(getPrimaryPublicKeyResp); 30 | std::cout << "Returned primary public key: " 31 | << getPrimaryPublicKeyResp.primay_public_key << std::endl; 32 | primaryPublicKey = util::hexToBin( 33 | getPrimaryPublicKeyResp.primay_public_key, kdf_.primary_public_key_bytes); 34 | } 35 | 36 | void SimpleAnonCredClient::getPublicKey( 37 | const std::vector& attributes) { 38 | auto attributeArrSize = attributes.size(); 39 | std::vector attributeArr; 40 | std::vector attributeLenArr; 41 | for (const std::string& s : attributes) { 42 | attributeLenArr.push_back(s.size()); 43 | attributeArr.push_back((const unsigned char*)s.data()); 44 | } 45 | 46 | thrift::GetPublicKeyRequest getPublicKeyReq; 47 | getPublicKeyReq.attributes = attributes; 48 | thrift::GetPublicKeyResponse getPublicKeyResp; 49 | thriftClient_.getPublicKeyAndProof(getPublicKeyResp, getPublicKeyReq); 50 | std::cout << "Returned public key: " << getPublicKeyResp.public_key 51 | << std::endl; 52 | std::cout << "Returned public key proof: " 53 | << getPublicKeyResp.public_key_proof << std::endl; 54 | publicKey = util::hexToBin(getPublicKeyResp.public_key, curve_.element_bytes); 55 | auto pkProof = util::hexToBin( 56 | getPublicKeyResp.public_key_proof, kdf_.public_key_proof_bytes); 57 | auto pkVerifyResult = kdf_.verify_public_key( 58 | &kdf_, 59 | publicKey.data(), 60 | publicKey.size(), 61 | pkProof.data(), 62 | pkProof.size(), 63 | primaryPublicKey.data(), 64 | primaryPublicKey.size(), 65 | attributeArrSize, 66 | attributeArr.data(), 67 | attributeLenArr.data()); 68 | 69 | if (pkVerifyResult == KDF_SUCCESS) { 70 | std::cout << "Public key proof validation success" << std::endl; 71 | } else { 72 | throw std::runtime_error("Public key proof validation failed"); 73 | } 74 | } 75 | 76 | void SimpleAnonCredClient::getCredential( 77 | const std::string& cred, 78 | const std::vector& attributes) { 79 | auto attributeArrSize = attributes.size(); 80 | std::vector attributeArr; 81 | std::vector attributeLenArr; 82 | for (const std::string& s : attributes) { 83 | attributeLenArr.push_back(s.size()); 84 | attributeArr.push_back((const unsigned char*)s.data()); 85 | } 86 | auto elementBytes = curve_.element_bytes; 87 | auto scalarBytes = curve_.scalar_bytes; 88 | 89 | // blind 90 | std::vector blindedElement(elementBytes); 91 | std::vector blindingFactor(scalarBytes); 92 | voprf_.blind( 93 | &voprf_, 94 | blindedElement.data(), 95 | blindedElement.size(), 96 | blindingFactor.data(), 97 | blindingFactor.size(), 98 | (const unsigned char*)cred.data(), 99 | cred.size()); 100 | auto blindedElementHex = util::binToHex(blindedElement); 101 | std::cout << "Blinded token: " << blindedElementHex << std::endl; 102 | 103 | // evaluate (sign, send to server) 104 | thrift::SignCredentialRequest signReq; 105 | thrift::SignCredentialResponse signResp; 106 | signReq.blinded_token = blindedElementHex; 107 | signReq.attributes = attributes; 108 | thriftClient_.signCredential(signResp, signReq); 109 | std::cout << "Returned evaluated token: " << signResp.evaluated_token 110 | << std::endl; 111 | auto blindedSignature = 112 | util::hexToBin(signResp.evaluated_token, elementBytes); 113 | auto proofC = util::hexToBin(signResp.proof_c, scalarBytes); 114 | auto proofS = util::hexToBin(signResp.proof_s, scalarBytes); 115 | 116 | // unblind and verify proof 117 | auto signatureVerifyResult = voprf_.verifiable_unblind( 118 | &voprf_, 119 | unBlindedElement.data(), 120 | unBlindedElement.size(), 121 | proofC.data(), 122 | proofC.size(), 123 | proofS.data(), 124 | proofS.size(), 125 | blindingFactor.data(), 126 | blindingFactor.size(), 127 | blindedSignature.data(), 128 | blindedSignature.size(), 129 | blindedElement.data(), 130 | blindedElement.size(), 131 | publicKey.data(), 132 | publicKey.size(), 133 | 1); 134 | if (signatureVerifyResult == VOPRF_SUCCESS) { 135 | std::cout << "Sign token proof verification success" << std::endl; 136 | } else { 137 | throw std::runtime_error("Sign token proof verification failed"); 138 | } 139 | std::cout << "Unblinded token: " << util::binToHex(unBlindedElement) 140 | << std::endl; 141 | } 142 | 143 | void SimpleAnonCredClient::redeemCredential( 144 | const std::string& cred, 145 | const std::vector& attributes) { 146 | auto attributeArrSize = attributes.size(); 147 | std::vector attributeArr; 148 | std::vector attributeLenArr; 149 | for (const std::string& s : attributes) { 150 | attributeLenArr.push_back(s.size()); 151 | attributeArr.push_back((const unsigned char*)s.data()); 152 | } 153 | auto elementBytes = curve_.element_bytes; 154 | auto scalarBytes = curve_.scalar_bytes; 155 | auto finalEvaluationBytes = voprf_.final_evaluation_bytes; 156 | std::vector clientSecret(finalEvaluationBytes); 157 | voprf_.client_finalize( 158 | &voprf_, 159 | clientSecret.data(), 160 | clientSecret.size(), 161 | (const unsigned char*)cred.data(), 162 | cred.size(), 163 | unBlindedElement.data(), 164 | unBlindedElement.size()); 165 | std::cout << "Client secret: " << util::binToHex(clientSecret) << std::endl; 166 | 167 | // redeem (server finalize, send to server) 168 | thrift::RedeemCredentialRequest redeemReq; 169 | redeemReq.token = cred; 170 | redeemReq.attributes = attributes; 171 | redeemReq.shared_secret = util::binToHex(clientSecret); 172 | try { 173 | thriftClient_.redeemCredential(redeemReq); 174 | std::cout << "Redeem credential success!" << std::endl; 175 | } catch (thrift::TokenEncodingException& e) { 176 | std::cout << "redeemCredential throws TokenEncodingException" << std::endl; 177 | } catch (thrift::VoprfErrorException& e) { 178 | std::cout << "redeemCredential throws VoprfErrorException with ErrorCode " 179 | << e.errorcode << std::endl; 180 | } catch (thrift::CredentialMismatchException& e) { 181 | std::cout << "redeemCredential failed. Credential mismatch!" << std::endl; 182 | } 183 | } 184 | 185 | } // namespace anon_cred 186 | -------------------------------------------------------------------------------- /src/crypto/curve/curve_ed25519.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | #include 10 | 11 | #include "src/crypto/curve/curve.h" 12 | #include "src/crypto/curve/curve_ed25519.h" 13 | 14 | static enum curve_error scalar_random(unsigned char* r, size_t r_len) { 15 | if (r_len != crypto_core_ed25519_SCALARBYTES) { 16 | return CURVE_BUFFER_LENGTH_ERROR; 17 | } 18 | crypto_core_ed25519_scalar_random(r); 19 | return CURVE_SUCCESS; 20 | } 21 | 22 | static enum curve_error scalar_add( 23 | unsigned char* z, 24 | size_t z_len, 25 | const unsigned char* x, 26 | size_t x_len, 27 | const unsigned char* y, 28 | size_t y_len) { 29 | if (z_len != crypto_core_ed25519_SCALARBYTES || 30 | x_len != crypto_core_ed25519_SCALARBYTES || 31 | y_len != crypto_core_ed25519_SCALARBYTES) { 32 | return CURVE_BUFFER_LENGTH_ERROR; 33 | } 34 | crypto_core_ed25519_scalar_add(z, x, y); 35 | return CURVE_SUCCESS; 36 | } 37 | 38 | static enum curve_error scalar_sub( 39 | unsigned char* z, 40 | size_t z_len, 41 | const unsigned char* x, 42 | size_t x_len, 43 | const unsigned char* y, 44 | size_t y_len) { 45 | if (z_len != crypto_core_ed25519_SCALARBYTES || 46 | x_len != crypto_core_ed25519_SCALARBYTES || 47 | y_len != crypto_core_ed25519_SCALARBYTES) { 48 | return CURVE_BUFFER_LENGTH_ERROR; 49 | } 50 | crypto_core_ed25519_scalar_sub(z, x, y); 51 | return CURVE_SUCCESS; 52 | } 53 | 54 | static enum curve_error scalar_mult( 55 | unsigned char* z, 56 | size_t z_len, 57 | const unsigned char* x, 58 | size_t x_len, 59 | const unsigned char* y, 60 | size_t y_len) { 61 | if (z_len != crypto_core_ed25519_SCALARBYTES || 62 | x_len != crypto_core_ed25519_SCALARBYTES || 63 | y_len != crypto_core_ed25519_SCALARBYTES) { 64 | return CURVE_BUFFER_LENGTH_ERROR; 65 | } 66 | crypto_core_ed25519_scalar_mul(z, x, y); 67 | return CURVE_SUCCESS; 68 | } 69 | 70 | static enum curve_error scalar_inv( 71 | unsigned char* r, 72 | size_t r_len, 73 | const unsigned char* s, 74 | size_t s_len) { 75 | if (r_len != crypto_core_ed25519_SCALARBYTES || 76 | s_len != crypto_core_ed25519_SCALARBYTES) { 77 | return CURVE_BUFFER_LENGTH_ERROR; 78 | } 79 | return crypto_core_ed25519_scalar_invert(r, s) ? CURVE_INVALID_INPUT 80 | : CURVE_SUCCESS; 81 | } 82 | 83 | static enum curve_error group_add( 84 | unsigned char* r, 85 | size_t r_len, 86 | const unsigned char* p, 87 | size_t p_len, 88 | const unsigned char* q, 89 | size_t q_len) { 90 | if (r_len != crypto_core_ed25519_BYTES || 91 | p_len != crypto_core_ed25519_BYTES || 92 | q_len != crypto_core_ed25519_BYTES) { 93 | return CURVE_BUFFER_LENGTH_ERROR; 94 | } 95 | return crypto_core_ed25519_add(r, p, q) ? CURVE_INVALID_INPUT : CURVE_SUCCESS; 96 | } 97 | 98 | static enum curve_error group_sub( 99 | unsigned char* r, 100 | size_t r_len, 101 | const unsigned char* p, 102 | size_t p_len, 103 | const unsigned char* q, 104 | size_t q_len) { 105 | if (r_len != crypto_core_ed25519_BYTES || 106 | p_len != crypto_core_ed25519_BYTES || 107 | q_len != crypto_core_ed25519_BYTES) { 108 | return CURVE_BUFFER_LENGTH_ERROR; 109 | } 110 | return crypto_core_ed25519_sub(r, p, q) ? CURVE_INVALID_INPUT : CURVE_SUCCESS; 111 | } 112 | 113 | static enum curve_error group_exp( 114 | unsigned char* q, 115 | size_t q_len, 116 | const unsigned char* n, 117 | size_t n_len, 118 | const unsigned char* p, 119 | size_t p_len) { 120 | if (q_len != crypto_core_ed25519_BYTES || 121 | n_len != crypto_core_ed25519_SCALARBYTES || 122 | p_len != crypto_core_ed25519_BYTES) { 123 | return CURVE_BUFFER_LENGTH_ERROR; 124 | } 125 | // The function verifies that p is on the prime-order subgroup before 126 | // performing the multiplication. return CURVE_INVALID_INPUT if not 127 | return crypto_scalarmult_ed25519_noclamp(q, n, p) ? CURVE_INVALID_INPUT 128 | : CURVE_SUCCESS; 129 | } 130 | 131 | static enum curve_error group_exp_generator( 132 | unsigned char* q, 133 | size_t q_len, 134 | const unsigned char* n, 135 | size_t n_len) { 136 | if (q_len != crypto_core_ed25519_BYTES || 137 | n_len != crypto_core_ed25519_SCALARBYTES) { 138 | return CURVE_BUFFER_LENGTH_ERROR; 139 | } 140 | return crypto_scalarmult_ed25519_base_noclamp(q, n) ? CURVE_INVALID_INPUT 141 | : CURVE_SUCCESS; 142 | } 143 | 144 | static enum curve_error check_on_curve(const unsigned char* p, size_t p_len) { 145 | if (p_len != crypto_core_ed25519_BYTES) { 146 | return CURVE_BUFFER_LENGTH_ERROR; 147 | } 148 | return crypto_core_ed25519_is_valid_point(p) ? CURVE_SUCCESS 149 | : CURVE_NOT_ON_CURVE; 150 | } 151 | 152 | static enum curve_error hash_to_scalar( 153 | unsigned char* result, 154 | const unsigned char** buf_arr, 155 | const size_t* buf_len, 156 | int n_buf) { 157 | unsigned char hash[crypto_hash_sha512_BYTES]; 158 | crypto_hash_sha512_state state; 159 | if (crypto_hash_sha512_init(&state)) { 160 | return CURVE_HASH_ERROR; 161 | }; 162 | for (int i = 0; i < n_buf; ++i) { 163 | if (crypto_hash_sha512_update(&state, buf_arr[i], buf_len[i])) { 164 | return CURVE_HASH_ERROR; 165 | } 166 | } 167 | if (crypto_hash_sha512_final(&state, hash)) { 168 | return CURVE_HASH_ERROR; 169 | } 170 | 171 | // Reduce to scalar 172 | crypto_core_ed25519_scalar_reduce(result, hash); 173 | return CURVE_SUCCESS; 174 | } 175 | 176 | // We use crypto_core_ed25519_from_uniform in this implementation 177 | // to align with the hash_to_point implementation in libsignal. 178 | static enum curve_error hash_to_curve( 179 | unsigned char* result, 180 | const unsigned char** buf_arr, 181 | const size_t* buf_len, 182 | int n_buf) { 183 | unsigned char hash[crypto_hash_sha512_BYTES]; 184 | crypto_hash_sha512_state state; 185 | if (crypto_hash_sha512_init(&state)) { 186 | return CURVE_HASH_ERROR; 187 | } 188 | for (int i = 0; i < n_buf; ++i) { 189 | if (crypto_hash_sha512_update(&state, buf_arr[i], buf_len[i])) { 190 | return CURVE_HASH_ERROR; 191 | } 192 | } 193 | if (crypto_hash_sha512_final(&state, hash)) { 194 | return CURVE_HASH_ERROR; 195 | } 196 | 197 | if (crypto_core_ed25519_from_uniform(result, hash)) { 198 | return CURVE_HASH_ERROR; 199 | } 200 | return CURVE_SUCCESS; 201 | } 202 | 203 | static enum curve_error get_generator(unsigned char* g, size_t g_len) { 204 | if (g_len != crypto_core_ed25519_BYTES) { 205 | return CURVE_BUFFER_LENGTH_ERROR; 206 | } 207 | // We get generator g by computing g^1 208 | // Create a scalar 1 with little endian 209 | static const unsigned char one[crypto_scalarmult_curve25519_SCALARBYTES] = { 210 | 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 211 | 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 212 | 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}; 213 | return crypto_scalarmult_ed25519_base_noclamp(g, one); 214 | } 215 | 216 | void curve_ed25519_init(curve_t* curve) { 217 | curve->scalar_bytes = crypto_core_ed25519_SCALARBYTES; 218 | curve->element_bytes = crypto_core_ed25519_BYTES; 219 | curve->scalar_random = scalar_random; 220 | curve->scalar_add = scalar_add; 221 | curve->scalar_sub = scalar_sub; 222 | curve->scalar_mult = scalar_mult; 223 | curve->scalar_inv = scalar_inv; 224 | curve->group_op = group_add; 225 | curve->group_inv_op = group_sub; 226 | curve->group_exp = group_exp; 227 | curve->group_exp_generator = group_exp_generator; 228 | curve->check_on_curve = check_on_curve; 229 | curve->hash_to_scalar = hash_to_scalar; 230 | curve->hash_to_curve = hash_to_curve; 231 | curve->get_generator = get_generator; 232 | } 233 | -------------------------------------------------------------------------------- /src/crypto/curve/curve_ristretto.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | 10 | #include "src/crypto/curve/curve.h" 11 | #include "src/crypto/curve/curve_ristretto.h" 12 | #include "sodium/crypto_core_ristretto255.h" 13 | 14 | static enum curve_error scalar_random(unsigned char* r, size_t r_len) { 15 | if (r_len != crypto_core_ristretto255_SCALARBYTES) { 16 | return CURVE_BUFFER_LENGTH_ERROR; 17 | } 18 | crypto_core_ristretto255_scalar_random(r); 19 | return CURVE_SUCCESS; 20 | } 21 | 22 | static enum curve_error scalar_add( 23 | unsigned char* z, 24 | size_t z_len, 25 | const unsigned char* x, 26 | size_t x_len, 27 | const unsigned char* y, 28 | size_t y_len) { 29 | if (z_len != crypto_core_ristretto255_SCALARBYTES || 30 | x_len != crypto_core_ristretto255_SCALARBYTES || 31 | y_len != crypto_core_ristretto255_SCALARBYTES) { 32 | return CURVE_BUFFER_LENGTH_ERROR; 33 | } 34 | crypto_core_ristretto255_scalar_add(z, x, y); 35 | return CURVE_SUCCESS; 36 | } 37 | 38 | static enum curve_error scalar_sub( 39 | unsigned char* z, 40 | size_t z_len, 41 | const unsigned char* x, 42 | size_t x_len, 43 | const unsigned char* y, 44 | size_t y_len) { 45 | if (z_len != crypto_core_ristretto255_SCALARBYTES || 46 | x_len != crypto_core_ristretto255_SCALARBYTES || 47 | y_len != crypto_core_ristretto255_SCALARBYTES) { 48 | return CURVE_BUFFER_LENGTH_ERROR; 49 | } 50 | crypto_core_ristretto255_scalar_sub(z, x, y); 51 | return CURVE_SUCCESS; 52 | } 53 | 54 | static enum curve_error scalar_mult( 55 | unsigned char* z, 56 | size_t z_len, 57 | const unsigned char* x, 58 | size_t x_len, 59 | const unsigned char* y, 60 | size_t y_len) { 61 | if (z_len != crypto_core_ristretto255_SCALARBYTES || 62 | x_len != crypto_core_ristretto255_SCALARBYTES || 63 | y_len != crypto_core_ristretto255_SCALARBYTES) { 64 | return CURVE_BUFFER_LENGTH_ERROR; 65 | } 66 | crypto_core_ristretto255_scalar_mul(z, x, y); 67 | return CURVE_SUCCESS; 68 | } 69 | 70 | static enum curve_error scalar_inv( 71 | unsigned char* r, 72 | size_t r_len, 73 | const unsigned char* s, 74 | size_t s_len) { 75 | if (r_len != crypto_core_ristretto255_SCALARBYTES || 76 | s_len != crypto_core_ristretto255_SCALARBYTES) { 77 | return CURVE_BUFFER_LENGTH_ERROR; 78 | } 79 | return crypto_core_ristretto255_scalar_invert(r, s) ? CURVE_INVALID_INPUT 80 | : CURVE_SUCCESS; 81 | } 82 | 83 | static enum curve_error group_add( 84 | unsigned char* r, 85 | size_t r_len, 86 | const unsigned char* p, 87 | size_t p_len, 88 | const unsigned char* q, 89 | size_t q_len) { 90 | if (r_len != crypto_core_ristretto255_BYTES || 91 | p_len != crypto_core_ristretto255_BYTES || 92 | q_len != crypto_core_ristretto255_BYTES) { 93 | return CURVE_BUFFER_LENGTH_ERROR; 94 | } 95 | return crypto_core_ristretto255_add(r, p, q) ? CURVE_INVALID_INPUT 96 | : CURVE_SUCCESS; 97 | } 98 | 99 | static enum curve_error group_sub( 100 | unsigned char* r, 101 | size_t r_len, 102 | const unsigned char* p, 103 | size_t p_len, 104 | const unsigned char* q, 105 | size_t q_len) { 106 | if (r_len != crypto_core_ristretto255_BYTES || 107 | p_len != crypto_core_ristretto255_BYTES || 108 | q_len != crypto_core_ristretto255_BYTES) { 109 | return CURVE_BUFFER_LENGTH_ERROR; 110 | } 111 | return crypto_core_ristretto255_sub(r, p, q) ? CURVE_INVALID_INPUT 112 | : CURVE_SUCCESS; 113 | } 114 | 115 | static enum curve_error group_exp( 116 | unsigned char* q, 117 | size_t q_len, 118 | const unsigned char* n, 119 | size_t n_len, 120 | const unsigned char* p, 121 | size_t p_len) { 122 | if (q_len != crypto_core_ristretto255_BYTES || 123 | n_len != crypto_core_ristretto255_SCALARBYTES || 124 | p_len != crypto_core_ristretto255_BYTES) { 125 | return CURVE_BUFFER_LENGTH_ERROR; 126 | } 127 | return crypto_scalarmult_ristretto255(q, n, p) ? CURVE_INVALID_INPUT 128 | : CURVE_SUCCESS; 129 | } 130 | 131 | static enum curve_error group_exp_generator( 132 | unsigned char* q, 133 | size_t q_len, 134 | const unsigned char* n, 135 | size_t n_len) { 136 | if (q_len != crypto_core_ristretto255_BYTES || 137 | n_len != crypto_core_ristretto255_SCALARBYTES) { 138 | return CURVE_BUFFER_LENGTH_ERROR; 139 | } 140 | return crypto_scalarmult_ristretto255_base(q, n) ? CURVE_INVALID_INPUT 141 | : CURVE_SUCCESS; 142 | } 143 | 144 | static enum curve_error check_on_curve(const unsigned char* p, size_t p_len) { 145 | if (p_len != crypto_core_ristretto255_BYTES) { 146 | return CURVE_BUFFER_LENGTH_ERROR; 147 | } 148 | return crypto_core_ristretto255_is_valid_point(p) ? CURVE_SUCCESS 149 | : CURVE_NOT_ON_CURVE; 150 | } 151 | 152 | static enum curve_error hash_to_scalar( 153 | unsigned char* result, 154 | const unsigned char** buf_arr, 155 | const size_t* buf_len, 156 | int n_buf) { 157 | unsigned char hash[crypto_hash_sha512_BYTES]; 158 | crypto_hash_sha512_state state; 159 | if (crypto_hash_sha512_init(&state)) { 160 | return CURVE_HASH_ERROR; 161 | }; 162 | for (int i = 0; i < n_buf; ++i) { 163 | if (crypto_hash_sha512_update(&state, buf_arr[i], buf_len[i])) { 164 | return CURVE_HASH_ERROR; 165 | } 166 | } 167 | if (crypto_hash_sha512_final(&state, hash)) { 168 | return CURVE_HASH_ERROR; 169 | } 170 | 171 | // Reduce to scalar 172 | crypto_core_ristretto255_scalar_reduce(result, hash); 173 | return CURVE_SUCCESS; 174 | } 175 | 176 | static enum curve_error hash_to_curve( 177 | unsigned char* result, 178 | const unsigned char** buf_arr, 179 | const size_t* buf_len, 180 | int n_buf) { 181 | unsigned char hash[crypto_hash_sha512_BYTES]; 182 | crypto_hash_sha512_state state; 183 | if (crypto_hash_sha512_init(&state)) { 184 | return CURVE_HASH_ERROR; 185 | } 186 | for (int i = 0; i < n_buf; ++i) { 187 | if (crypto_hash_sha512_update(&state, buf_arr[i], buf_len[i])) { 188 | return CURVE_HASH_ERROR; 189 | } 190 | } 191 | if (crypto_hash_sha512_final(&state, hash)) { 192 | return CURVE_HASH_ERROR; 193 | } 194 | if (crypto_core_ristretto255_from_hash(result, hash)) { 195 | return CURVE_HASH_ERROR; 196 | } 197 | return CURVE_SUCCESS; 198 | } 199 | 200 | static enum curve_error get_generator(unsigned char* g, size_t g_len) { 201 | if (g_len != crypto_core_ristretto255_BYTES) { 202 | return CURVE_BUFFER_LENGTH_ERROR; 203 | } 204 | // We get generator g by computing g^1 205 | // Create a scalar 1 with little endian 206 | static const unsigned char one[crypto_scalarmult_curve25519_SCALARBYTES] = { 207 | 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 208 | 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 209 | 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}; 210 | return crypto_scalarmult_ristretto255_base(g, one); 211 | } 212 | 213 | void curve_ristretto_init(curve_t* curve) { 214 | curve->scalar_bytes = crypto_core_ristretto255_SCALARBYTES; 215 | curve->element_bytes = crypto_core_ristretto255_BYTES; 216 | curve->scalar_random = scalar_random; 217 | curve->scalar_add = scalar_add; 218 | curve->scalar_sub = scalar_sub; 219 | curve->scalar_mult = scalar_mult; 220 | curve->scalar_inv = scalar_inv; 221 | curve->group_op = group_add; 222 | curve->group_inv_op = group_sub; 223 | curve->group_exp = group_exp; 224 | curve->group_exp_generator = group_exp_generator; 225 | curve->check_on_curve = check_on_curve; 226 | curve->hash_to_scalar = hash_to_scalar; 227 | curve->hash_to_curve = hash_to_curve; 228 | curve->get_generator = get_generator; 229 | } 230 | -------------------------------------------------------------------------------- /src/crypto/dleqproof/dleqproof.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | 10 | #include "src/crypto/curve/curve.h" 11 | #include "src/crypto/dleqproof/dleqproof.h" 12 | 13 | #define CURVE_SUCCESS_CHECK(EXP) \ 14 | if (EXP != CURVE_SUCCESS) { \ 15 | return DLEQPROOF_CURVE_OPERATION_ERROR; \ 16 | } 17 | 18 | static enum dleqproof_error dleqproof_generate_proof_hash_challenge( 19 | curve_t* curve, 20 | unsigned char* proof_hash_challenge, 21 | size_t proof_hash_challenge_len, 22 | const unsigned char* base1, 23 | size_t base1_len, 24 | const unsigned char* base2, 25 | size_t base2_len, 26 | const unsigned char* element1, 27 | size_t element1_len, 28 | const unsigned char* element2, 29 | size_t element2_len, 30 | const unsigned char* r_base1, 31 | size_t r_base1_len, 32 | const unsigned char* r_base2, 33 | size_t r_base2_len) { 34 | size_t element_bytes = curve->element_bytes; 35 | size_t scalar_bytes = curve->scalar_bytes; 36 | if (proof_hash_challenge_len != scalar_bytes || base1_len != element_bytes || 37 | base2_len != element_bytes || element1_len != element_bytes || 38 | element2_len != element_bytes || r_base1_len != element_bytes || 39 | r_base2_len != element_bytes) { 40 | return DLEQPROOF_BUFFER_LENGTH_ERROR; 41 | } 42 | 43 | CURVE_SUCCESS_CHECK(curve->hash_to_scalar( 44 | proof_hash_challenge, /* result */ 45 | (const unsigned char*[]){ 46 | base1, element1, base2, element2, r_base1, r_base2}, /* buf_arr */ 47 | (const size_t[]){ 48 | element_bytes, 49 | element_bytes, 50 | element_bytes, 51 | element_bytes, 52 | element_bytes, 53 | element_bytes}, /* buf_len */ 54 | 6 /* n_buf */)); 55 | return DLEQPROOF_SUCCESS; 56 | } 57 | 58 | static enum dleqproof_error dleqproof_prove( 59 | dleqproof_protocol_t* protocol, 60 | unsigned char* proof_c, 61 | size_t proof_c_len, 62 | unsigned char* proof_s, 63 | size_t proof_s_len, 64 | const unsigned char* base1, 65 | size_t base1_len, 66 | const unsigned char* base2, 67 | size_t base2_len, 68 | const unsigned char* element1, 69 | size_t element1_len, 70 | const unsigned char* element2, 71 | size_t element2_len, 72 | const unsigned char* discrete_log, 73 | size_t discrete_log_len) { 74 | size_t element_bytes = protocol->curve->element_bytes; 75 | size_t scalar_bytes = protocol->curve->scalar_bytes; 76 | 77 | if (proof_c_len != scalar_bytes || proof_s_len != scalar_bytes || 78 | base1_len != element_bytes || base2_len != element_bytes || 79 | element1_len != element_bytes || element2_len != element_bytes || 80 | discrete_log_len != scalar_bytes) { 81 | return DLEQPROOF_BUFFER_LENGTH_ERROR; 82 | } 83 | 84 | // Sample a random scalar r 85 | unsigned char r[scalar_bytes]; 86 | CURVE_SUCCESS_CHECK(protocol->curve->scalar_random(r, scalar_bytes)); 87 | 88 | // Compute base1 ^ r 89 | unsigned char r_base1[element_bytes]; 90 | CURVE_SUCCESS_CHECK(protocol->curve->group_exp( 91 | r_base1, element_bytes, r, scalar_bytes, base1, element_bytes)); 92 | 93 | // Compute base2 ^ r 94 | unsigned char r_base2[element_bytes]; 95 | CURVE_SUCCESS_CHECK(protocol->curve->group_exp( 96 | r_base2, element_bytes, r, scalar_bytes, base2, element_bytes)); 97 | 98 | // Compute hash challenge 99 | enum dleqproof_error generate_proof_hash_challenge_error = 100 | dleqproof_generate_proof_hash_challenge( 101 | protocol->curve, 102 | proof_c, 103 | proof_c_len, 104 | base1, 105 | base1_len, 106 | base2, 107 | base2_len, 108 | element1, 109 | element1_len, 110 | element2, 111 | element2_len, 112 | r_base1 /* base1^r */, 113 | element_bytes, 114 | r_base2 /* base2^r */, 115 | element_bytes); 116 | if (generate_proof_hash_challenge_error != DLEQPROOF_SUCCESS) { 117 | return generate_proof_hash_challenge_error; 118 | } 119 | 120 | // Compute challenge response: s <- (r - c * discreteLog) 121 | unsigned char tmp[scalar_bytes]; 122 | CURVE_SUCCESS_CHECK(protocol->curve->scalar_mult( 123 | tmp, scalar_bytes, proof_c, scalar_bytes, discrete_log, scalar_bytes)); 124 | CURVE_SUCCESS_CHECK(protocol->curve->scalar_sub( 125 | proof_s, scalar_bytes, r, scalar_bytes, tmp, scalar_bytes)); 126 | return DLEQPROOF_SUCCESS; 127 | } 128 | 129 | static enum dleqproof_error dleqproof_verify( 130 | dleqproof_protocol_t* protocol, 131 | const unsigned char* proof_c, 132 | size_t proof_c_len, 133 | const unsigned char* proof_s, 134 | size_t proof_s_len, 135 | const unsigned char* base1, 136 | size_t base1_len, 137 | const unsigned char* base2, 138 | size_t base2_len, 139 | const unsigned char* element1, 140 | size_t element1_len, 141 | const unsigned char* element2, 142 | size_t element2_len) { 143 | size_t element_bytes = protocol->curve->element_bytes; 144 | size_t scalar_bytes = protocol->curve->scalar_bytes; 145 | 146 | if (proof_c_len != scalar_bytes || proof_s_len != scalar_bytes || 147 | base1_len != element_bytes || base2_len != element_bytes || 148 | element1_len != element_bytes || element2_len != element_bytes) { 149 | return DLEQPROOF_BUFFER_LENGTH_ERROR; 150 | } 151 | 152 | // Compute randomized bases: 153 | // r_base1 <- base1^s * element1^c 154 | // r_base2 <- base2^s * element2^c 155 | // we expect r_base1 = base1 ^ r, r_base2 = base2 ^ r 156 | unsigned char tmp_base_s1[element_bytes]; 157 | unsigned char tmp_element_c1[element_bytes]; 158 | unsigned char r_base1[element_bytes]; 159 | unsigned char tmp_base_s2[element_bytes]; 160 | unsigned char tmp_element_c2[element_bytes]; 161 | unsigned char r_base2[element_bytes]; 162 | 163 | CURVE_SUCCESS_CHECK(protocol->curve->group_exp( 164 | tmp_base_s1, element_bytes, proof_s, scalar_bytes, base1, element_bytes)); 165 | 166 | CURVE_SUCCESS_CHECK(protocol->curve->group_exp( 167 | tmp_element_c1, 168 | element_bytes, 169 | proof_c, 170 | scalar_bytes, 171 | element1, 172 | element_bytes)); 173 | CURVE_SUCCESS_CHECK(protocol->curve->group_op( 174 | r_base1, 175 | element_bytes, 176 | tmp_base_s1, 177 | element_bytes, 178 | tmp_element_c1, 179 | element_bytes)); 180 | CURVE_SUCCESS_CHECK(protocol->curve->group_exp( 181 | tmp_base_s2, element_bytes, proof_s, scalar_bytes, base2, element_bytes)); 182 | CURVE_SUCCESS_CHECK(protocol->curve->group_exp( 183 | tmp_element_c2, 184 | element_bytes, 185 | proof_c, 186 | scalar_bytes, 187 | element2, 188 | element_bytes)); 189 | CURVE_SUCCESS_CHECK(protocol->curve->group_op( 190 | r_base2, 191 | element_bytes, 192 | tmp_base_s2, 193 | element_bytes, 194 | tmp_element_c2, 195 | element_bytes)); 196 | // Compute hash challenge 197 | unsigned char c[scalar_bytes]; 198 | enum dleqproof_error generate_proof_hash_challenge_error = 199 | dleqproof_generate_proof_hash_challenge( 200 | protocol->curve, 201 | c, 202 | scalar_bytes, 203 | base1, 204 | base1_len, 205 | base2, 206 | base2_len, 207 | element1, 208 | element1_len, 209 | element2, 210 | element2_len, 211 | r_base1, 212 | element_bytes, 213 | r_base2, 214 | element_bytes); 215 | if (generate_proof_hash_challenge_error != DLEQPROOF_SUCCESS) { 216 | return generate_proof_hash_challenge_error; 217 | } 218 | // Compare computed challenge with claimed proof challenge 219 | return sodium_memcmp(proof_c, c, scalar_bytes) ? DLEQPROOF_VERIFY_FAIL 220 | : DLEQPROOF_SUCCESS; 221 | } 222 | 223 | void dleqproof_init(dleqproof_protocol_t* protocol, curve_t* curve) { 224 | protocol->curve = curve; 225 | protocol->prove = dleqproof_prove; 226 | protocol->verify = dleqproof_verify; 227 | } 228 | -------------------------------------------------------------------------------- /src/crypto/voprf/voprf.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #pragma once 9 | 10 | #include 11 | 12 | #include "src/crypto/curve/curve.h" 13 | 14 | enum voprf_error { 15 | VOPRF_SUCCESS = 0, 16 | VOPRF_UNKNOWN_ERROR = -1, 17 | VOPRF_BUFFER_LENGTH_ERROR = 1, 18 | VOPRF_CURVE_OPERATION_ERROR = 2, 19 | VOPRF_HASH_OPERATION_ERROR = 3, 20 | VOPRF_PROOF_ERROR = 4, 21 | }; 22 | 23 | /** 24 | * User interface for VOPRF library. See demo.c for examples. 25 | * 26 | * (Double) Hashed Diffie-Hellman (two hash DH) implementations with exponential 27 | * blinding and multiplactive blinding are provided. 28 | */ 29 | 30 | typedef struct voprf voprf_t; 31 | 32 | struct voprf { 33 | /** 34 | * The length of final evaluation used in this VOPRF protocol. 35 | */ 36 | size_t final_evaluation_bytes; 37 | 38 | /** 39 | * The elliptic curve used in this VOPRF protocol. 40 | */ 41 | curve_t* curve; 42 | 43 | /** 44 | * Computes a (sk, pk) pair. 45 | * This method is designed for demo. In real applications consider using key 46 | * pairs generated from KDF. 47 | * 48 | * @param voprf A pointer to voprf struct. 49 | * @param sk Mutable unsigned char buffer for secret key. 50 | * @param sk_len The size of this buffer should be scalar_bytes of the curve. 51 | * @param pk Mutable unsigned char buffer for public key. 52 | * @param pk_len The size of this buffer should be element_bytes of the curve. 53 | */ 54 | enum voprf_error (*setup)( 55 | voprf_t* /* voprf */, 56 | unsigned char* /* sk */, 57 | size_t /* sk_len */, 58 | unsigned char* /* pk */, 59 | size_t /* pk_len */); 60 | 61 | /** 62 | * (Client side) Blind a token, generate a blinded_element and a 63 | * blinding_factor. blinded_element is supposed to be sent to server for 64 | * evaluation. blinding_factor is random generated and should be stored on 65 | * client for unblinding. 66 | * 67 | * @param voprf A pointer to voprf struct. 68 | * @param blinded_element Mutable unsigned char buffer for blinded_element. 69 | * @param blinded_element_len The size of this buffer should be element_bytes 70 | * of the curve. 71 | * @param blinding_factor Mutable unsigned char buffer for blinding_factor. 72 | * @param blinding_factor_len The size of this buffer should be scalar_bytes 73 | * of the curve. 74 | * @param input Unsigned char buffer for input token. We recommend using 75 | * random generated tokens. 76 | * @param input_len The size of input buffer. 77 | */ 78 | enum voprf_error (*blind)( 79 | voprf_t* /* voprf */, 80 | unsigned char* /* blinded_element */, 81 | size_t /* blinded_element_len */, 82 | unsigned char* /* blinding_factor */, 83 | size_t /* blinding_factor_len */, 84 | const unsigned char* /* input */, 85 | const size_t /* input_len */); 86 | 87 | /** 88 | * (Server side) Evalutate a blinded_element from client, and optionally 89 | * generate a DLEQPROOF 90 | * 91 | * @param voprf A pointer to voprf struct. 92 | * @param evaluated_element Mutable unsigned char buffer for 93 | * evaluated_element. 94 | * @param evaluated_element_len The size of this buffer should be 95 | * element_bytes of the curve. 96 | * @param proof_c Mutable unsigned char buffers for proof_c. This is optional 97 | * if flag_proof_generate = 0. 98 | * @param proof_c_len The size of this buffer should be scalar_bytes of the 99 | * curve. This is optional if flag_proof_generate = 0 100 | * @param proof_s Mutable unsigned char buffers for proof_s. This is optional 101 | * if flag_proof_generate = 0. 102 | * @param proof_s_len The size of this buffer should be scalar_bytes of the 103 | * curve. This is optional if flag_proof_generate = 0 104 | * @param sk Unsigned char buffer for secret key. 105 | * @param sk_len The size of this buffer should be scalar_bytes of the curve. 106 | * @param blinded_element Unsigned char buffer for blinded_element to be 107 | * evaluated. 108 | * @param blinded_element_len The size of this buffer should be element_bytes 109 | * of the curve. 110 | * @param flag_proof_generate Use flag_proof_generate = 1 if DLEQPROOF is 111 | * needed, 0 otherwise. 112 | */ 113 | enum voprf_error (*evaluate)( 114 | voprf_t* /* voprf */, 115 | unsigned char* /* evaluated_element */, 116 | size_t /* evaluated_element_len */, 117 | unsigned char* /* proof_c */, 118 | size_t /* proof_c_len */, 119 | unsigned char* /* proof_s */, 120 | size_t /* proof_s_len */, 121 | const unsigned char* /* sk */, 122 | size_t /* sk_len */, 123 | const unsigned char* /* blinded_element */, 124 | size_t /* blinded_element_len */, 125 | int /* flag_proof_generate */); 126 | 127 | /** 128 | * (Client side) Unblind token, and optionally check DLEQPROOF from server. 129 | * 130 | * @param voprf A pointer to voprf struct. 131 | * @param unblinded_element Mutable unsigned char buffer for 132 | * unblinded_element. 133 | * @param unblinded_element_len The size of this buffer should be 134 | * element_bytes of the curve. 135 | * @param proof_c Unsigned char buffers for proof_c. This is optional if 136 | * flag_proof_generate = 0. 137 | * @param proof_c_len The size of this buffer should be scalar_bytes of the 138 | * curve. This is optional if flag_proof_generate = 0 139 | * @param proof_s unsigned char buffers for proof_s. This is optional if 140 | * flag_proof_generate = 0. 141 | * @param proof_s_len The size of this buffer should be scalar_bytes of the 142 | * curve. This is optional if flag_proof_generate = 0 143 | * @param blinding_factor Unsigned char buffer for blinding_factor generated 144 | * from blind(). 145 | * @param blinding_factor_len The size of this buffer should be scalar_bytes 146 | * of the curve. 147 | * @param evaluated_element Unsigned char buffer for evaluated_element from 148 | * server. 149 | * @param evaluated_element_len The size of this buffer should be 150 | * element_bytes of the curve. 151 | * @param blinded_element Unsigned char buffer for blinded_element generated 152 | * from blind(). 153 | * @param blinded_element_len The size of this buffer should be element_bytes 154 | * of the curve. 155 | * @param pk Unsigned char buffer for private key. 156 | * @param pk_len The size of this buffer should be element_bytes of the curve. 157 | * @param flag_proof_generate Use flag_proof_generate = 1 if DLEQPROOF is 158 | * needed, 0 otherwise. 159 | */ 160 | enum voprf_error (*verifiable_unblind)( 161 | voprf_t* /* voprf */, 162 | unsigned char* /* unblinded_element */, 163 | size_t /* unblinded_element_len */, 164 | const unsigned char* /* proof_c */, 165 | size_t /* proof_c_len */, 166 | const unsigned char* /* proof_s */, 167 | size_t /* proof_s_len */, 168 | const unsigned char* /* blinding_factor */, 169 | size_t /* blinding_factor_len */, 170 | const unsigned char* /* evaluated_element */, 171 | size_t /* evaluated_element_len */, 172 | const unsigned char* /* blinded_element */, 173 | size_t /* blinded_element_len */, 174 | const unsigned char* /* pk */, 175 | size_t /* pk_len */, 176 | int /* flag_proof_verify */); 177 | 178 | /** 179 | * (Client side) Generate a shared secret for redemption. 180 | * 181 | * @param voprf A pointer to voprf struct. 182 | * @param final_evaluation Mutable unsigned char buffer for shared secret 183 | * (output). 184 | * @param final_evaluation_len The size of this buffer should be 185 | * final_evaluation_bytes. 186 | * @param input unsigned char buffer for input token used in blind(). 187 | * @param input_size The size of input buffer. 188 | * @param unblinded_element unsigned char buffer for unblinded_element 189 | * generated from element_bytes(). 190 | * @param unblinded_element_len The size of this buffer should be 191 | * element_bytes of the curve. 192 | */ 193 | enum voprf_error (*client_finalize)( 194 | voprf_t* /* voprf */, 195 | unsigned char* /* final_evaluation */, 196 | size_t /* final_evaluation_len */, 197 | const unsigned char* /* input */, 198 | size_t /* input_len */, 199 | const unsigned char* /* unblinded_element */, 200 | size_t /* unblinded_element_len */ 201 | ); 202 | 203 | /** 204 | * (Server side) Generate a shared secret for redemption. 205 | * 206 | * @param voprf A pointer to voprf struct. 207 | * @param final_evaluation Mutable unsigned char buffer for shared secret 208 | * (output). 209 | * @param final_evaluation_len The size of this buffer should be 210 | * final_evaluation_bytes. 211 | * @param input unsigned char buffer for input token used in blind(). 212 | * @param input_size The size of input buffer. 213 | * @param sk Unsigned char buffer for secret key. 214 | * @param sk_len The size of this buffer should be scalar_bytes of the curve. 215 | */ 216 | enum voprf_error (*server_finalize)( 217 | voprf_t* /* voprf */, 218 | unsigned char* /* final_evaluation */, 219 | size_t /* final_evaluation_len */, 220 | const unsigned char* /* input */, 221 | size_t /* input_len */, 222 | const unsigned char* /* sk */, 223 | size_t /* sk_len */ 224 | ); 225 | }; 226 | -------------------------------------------------------------------------------- /tests/kdf_test.cpp: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | #include 10 | #include 11 | extern "C" { 12 | #include "src/crypto/curve/curve_ed25519.h" 13 | #include "src/crypto/curve/curve_ristretto.h" 14 | #include "src/crypto/kdf/kdf_default.h" 15 | #include "src/crypto/kdf/kdf_naor_reingold.h" 16 | #include "src/crypto/kdf/kdf_sdhi.h" 17 | #include "src/crypto/voprf/voprf_exp_twohashdh.h" 18 | #include "src/crypto/voprf/voprf_mul_twohashdh.h" 19 | } 20 | 21 | namespace { 22 | 23 | enum class CryptoCurve { 24 | CURVE_RISTRETTO, 25 | CURVE_ED25519, 26 | }; 27 | 28 | enum class Kdf { 29 | KDF_DEFAULT, 30 | KDF_NAOR_REINGOLD, 31 | KDF_SDHI, 32 | }; 33 | 34 | enum class Blinding { 35 | MULTIPLICATIVE, 36 | EXPONENTIAL, 37 | }; 38 | 39 | struct KdfTest 40 | : public testing::TestWithParam> { 41 | void SetUp() override { 42 | auto testParam = GetParam(); 43 | switch (std::get<0>(testParam)) { 44 | case CryptoCurve::CURVE_ED25519: 45 | curve_ed25519_init(&curve_); 46 | break; 47 | case CryptoCurve::CURVE_RISTRETTO: 48 | curve_ristretto_init(&curve_); 49 | break; 50 | } 51 | switch (std::get<1>(testParam)) { 52 | case Kdf::KDF_DEFAULT: 53 | kdf_default_init(&kdf_, &curve_); 54 | break; 55 | case Kdf::KDF_SDHI: 56 | kdf_sdhi_init(&kdf_, &curve_); 57 | break; 58 | case Kdf::KDF_NAOR_REINGOLD: 59 | // kdf_sdhi_init(&kdf_, &curve_); 60 | kdf_naor_reingold_init(&kdf_, &curve_); 61 | break; 62 | } 63 | switch (std::get<2>(testParam)) { 64 | case Blinding::EXPONENTIAL: 65 | voprf_exp_twohashdh_init(&voprf_, &curve_); 66 | break; 67 | case Blinding::MULTIPLICATIVE: 68 | voprf_mul_twohashdh_init(&voprf_, &curve_); 69 | break; 70 | } 71 | } 72 | 73 | void TearDown() override {} 74 | 75 | curve_t curve_; 76 | kdf_t kdf_; 77 | voprf_t voprf_; 78 | }; 79 | 80 | TEST_P(KdfTest, KeyPairTest) { 81 | const size_t primary_key_len = kdf_.primary_key_bytes; 82 | unsigned char primary_key[primary_key_len]; 83 | EXPECT_EQ( 84 | kdf_.generate_primary_key(&kdf_, primary_key, primary_key_len), 85 | KDF_SUCCESS); 86 | 87 | const unsigned char* attribute_arr[2] = { 88 | (const unsigned char*)"some_random_string", 89 | (const unsigned char*)"123456"}; 90 | const size_t attribute_len_arr[2] = {18, 6}; 91 | 92 | const size_t sk_len = curve_.scalar_bytes; 93 | const size_t pk_len = curve_.element_bytes; 94 | unsigned char sk[sk_len]; 95 | unsigned char pk[pk_len]; 96 | EXPECT_EQ( 97 | kdf_.derive_key_pair( 98 | &kdf_, 99 | sk, 100 | sk_len, 101 | pk, 102 | pk_len, 103 | NULL, 104 | 0, 105 | primary_key, 106 | primary_key_len, 107 | 2, 108 | attribute_arr, 109 | attribute_len_arr, 110 | 0), 111 | KDF_SUCCESS); 112 | 113 | // Check g^sk = pk for derived key pair 114 | unsigned char g_sk[pk_len]; 115 | curve_.group_exp_generator( 116 | g_sk, curve_.element_bytes, sk, curve_.scalar_bytes); 117 | EXPECT_EQ(sodium_memcmp(g_sk, pk, curve_.element_bytes), 0); 118 | } 119 | 120 | TEST_P(KdfTest, ProofTest) { 121 | size_t primary_key_len = kdf_.primary_key_bytes; 122 | unsigned char primary_key[primary_key_len]; 123 | EXPECT_EQ( 124 | kdf_.generate_primary_key(&kdf_, primary_key, primary_key_len), 125 | KDF_SUCCESS); 126 | 127 | const unsigned char* attribute_arr[2] = { 128 | (const unsigned char*)"some_random_string", 129 | (const unsigned char*)"123456"}; 130 | const unsigned char* another_attribute_arr[2] = { 131 | (const unsigned char*)"some_random_string", 132 | (const unsigned char*)"abcdef"}; 133 | const size_t attribute_len_arr[2] = {18, 6}; 134 | 135 | size_t sk_len = curve_.scalar_bytes; 136 | size_t pk_len = curve_.element_bytes; 137 | size_t pk_proof_len = kdf_.public_key_proof_bytes; 138 | unsigned char sk[sk_len]; 139 | unsigned char pk[pk_len]; 140 | unsigned char pk_proof[pk_proof_len]; 141 | EXPECT_EQ( 142 | kdf_.derive_key_pair( 143 | &kdf_, 144 | sk, 145 | sk_len, 146 | pk, 147 | pk_len, 148 | pk_proof, 149 | pk_proof_len, 150 | primary_key, 151 | primary_key_len, 152 | 2, 153 | attribute_arr, 154 | attribute_len_arr, 155 | 1), 156 | KDF_SUCCESS); 157 | 158 | unsigned char ppk[kdf_.primary_public_key_bytes]; 159 | kdf_.derive_primary_public_key( 160 | &kdf_, ppk, kdf_.primary_public_key_bytes, primary_key, primary_key_len); 161 | EXPECT_EQ( 162 | kdf_.verify_public_key( 163 | &kdf_, 164 | pk, 165 | pk_len, 166 | pk_proof, 167 | pk_proof_len, 168 | ppk, 169 | kdf_.primary_public_key_bytes, 170 | 2, 171 | attribute_arr, 172 | attribute_len_arr), 173 | KDF_SUCCESS); 174 | 175 | if (pk_proof_len > 0) { 176 | // pass another attribute array, verification should fail 177 | EXPECT_EQ( 178 | kdf_.verify_public_key( 179 | &kdf_, 180 | pk, 181 | pk_len, 182 | pk_proof, 183 | pk_proof_len, 184 | ppk, 185 | kdf_.primary_public_key_bytes, 186 | 2, 187 | another_attribute_arr, 188 | attribute_len_arr), 189 | KDF_PK_PROOF_ERROR); 190 | 191 | // corrupt proof byte to make proof verification fail 192 | pk_proof[0] += 1; 193 | EXPECT_EQ( 194 | kdf_.verify_public_key( 195 | &kdf_, 196 | pk, 197 | pk_len, 198 | pk_proof, 199 | pk_proof_len, 200 | ppk, 201 | kdf_.primary_public_key_bytes, 202 | 2, 203 | attribute_arr, 204 | attribute_len_arr), 205 | KDF_PK_PROOF_ERROR); 206 | } 207 | } 208 | 209 | TEST_P(KdfTest, VoprfWorkflowTest) { 210 | const size_t primary_key_len = kdf_.primary_key_bytes; 211 | unsigned char primary_key[primary_key_len]; 212 | EXPECT_EQ( 213 | kdf_.generate_primary_key(&kdf_, primary_key, primary_key_len), 214 | KDF_SUCCESS); 215 | 216 | const unsigned char* attribute_arr[2] = { 217 | (const unsigned char*)"some_random_string", 218 | (const unsigned char*)"123456"}; 219 | const size_t attribute_len_arr[2] = {18, 6}; 220 | 221 | const size_t sk_len = curve_.scalar_bytes; 222 | const size_t pk_len = curve_.element_bytes; 223 | unsigned char sk[sk_len]; 224 | unsigned char pk[pk_len]; 225 | EXPECT_EQ( 226 | kdf_.derive_key_pair( 227 | &kdf_, 228 | sk, 229 | sk_len, 230 | pk, 231 | pk_len, 232 | NULL, 233 | 0, 234 | primary_key, 235 | primary_key_len, 236 | 2, 237 | attribute_arr, 238 | attribute_len_arr, 239 | 0), 240 | KDF_SUCCESS); 241 | 242 | unsigned char* token = (unsigned char*)"test"; 243 | const size_t token_len = 4; 244 | 245 | // blind 246 | const size_t blinded_element_len = curve_.element_bytes; 247 | const size_t blinding_factor_len = curve_.scalar_bytes; 248 | unsigned char blinded_element[blinded_element_len]; 249 | unsigned char blinding_factor[blinding_factor_len]; 250 | EXPECT_EQ( 251 | voprf_.blind( 252 | &voprf_, 253 | blinded_element, 254 | blinded_element_len, 255 | blinding_factor, 256 | blinding_factor_len, 257 | token, 258 | token_len), 259 | VOPRF_SUCCESS); 260 | 261 | // evaluate 262 | const size_t evaluated_element_len = curve_.element_bytes; 263 | unsigned char evaluated_element[evaluated_element_len]; 264 | const size_t proof_c_len = curve_.scalar_bytes; 265 | unsigned char proof_c[proof_c_len]; 266 | const size_t proof_s_len = curve_.scalar_bytes; 267 | unsigned char proof_s[proof_s_len]; 268 | EXPECT_EQ( 269 | voprf_.evaluate( 270 | &voprf_, 271 | evaluated_element, 272 | evaluated_element_len, 273 | proof_c, 274 | proof_c_len, 275 | proof_s, 276 | proof_s_len, 277 | sk, 278 | sk_len, 279 | blinded_element, 280 | blinded_element_len, 281 | 1 /* flag_proof_generate */), 282 | VOPRF_SUCCESS); 283 | 284 | // unblind 285 | const size_t unblinded_element_len = curve_.element_bytes; 286 | unsigned char unblinded_element[unblinded_element_len]; 287 | EXPECT_EQ( 288 | voprf_.verifiable_unblind( 289 | &voprf_, 290 | unblinded_element, 291 | unblinded_element_len, 292 | proof_c, 293 | proof_c_len, 294 | proof_s, 295 | proof_s_len, 296 | blinding_factor, 297 | blinding_factor_len, 298 | evaluated_element, 299 | evaluated_element_len, 300 | blinded_element, 301 | blinded_element_len, 302 | pk, 303 | pk_len, 304 | 1 /* flag_proof_verify */), 305 | VOPRF_SUCCESS); 306 | 307 | // client finalize 308 | const size_t client_secret_len = voprf_.final_evaluation_bytes; 309 | unsigned char client_secret[client_secret_len]; 310 | EXPECT_EQ( 311 | voprf_.client_finalize( 312 | &voprf_, 313 | client_secret, 314 | client_secret_len, 315 | token, 316 | token_len, 317 | unblinded_element, 318 | unblinded_element_len), 319 | VOPRF_SUCCESS); 320 | 321 | // server finalize 322 | const size_t server_secret_len = voprf_.final_evaluation_bytes; 323 | unsigned char server_secret[server_secret_len]; 324 | EXPECT_EQ( 325 | voprf_.server_finalize( 326 | &voprf_, 327 | server_secret, 328 | server_secret_len, 329 | token, 330 | token_len, 331 | sk, 332 | sk_len), 333 | VOPRF_SUCCESS); 334 | 335 | EXPECT_EQ( 336 | sodium_memcmp( 337 | client_secret, server_secret, voprf_.final_evaluation_bytes), 338 | 0); 339 | } 340 | 341 | INSTANTIATE_TEST_SUITE_P( 342 | VariableCurveKDFBlinding, 343 | KdfTest, 344 | testing::Combine( 345 | testing::Values( 346 | CryptoCurve::CURVE_ED25519, 347 | CryptoCurve::CURVE_RISTRETTO), 348 | testing::Values( 349 | Kdf::KDF_DEFAULT, 350 | Kdf::KDF_SDHI, 351 | Kdf::KDF_NAOR_REINGOLD), 352 | testing::Values(Blinding::MULTIPLICATIVE, Blinding::EXPONENTIAL))); 353 | 354 | } // namespace 355 | -------------------------------------------------------------------------------- /src/crypto/curve/curve.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #pragma once 9 | 10 | #include 11 | 12 | enum curve_error { 13 | CURVE_SUCCESS = 0, 14 | CURVE_UNKNOWN_ERROR = -1, 15 | CURVE_BUFFER_LENGTH_ERROR = 1, 16 | CURVE_INVALID_INPUT = 2, 17 | CURVE_NOT_ON_CURVE = 3, 18 | CURVE_HASH_ERROR = 4 19 | }; 20 | 21 | /** 22 | * An interface for elliptic curve operations. 23 | * 24 | * The interface is designed for easy linking its function pointer members to 25 | * libsodium lib functions, although creating an implementation without 26 | * libsodium is possible. We also implement additional functions: 27 | * hash_to_scalar, hash_to_curve, get_generator, get_scalar_bytes, and 28 | * get_element_bytes for each curve. 29 | * 30 | * Default implementation for CURVE_ED25519 and CURVE_RISTRETTO is provided with 31 | * VOPRF lib. 32 | */ 33 | 34 | typedef struct curve { 35 | /** 36 | * A curve is defined on finite field F_Q over a prime order Q. Choose an 37 | * Elliptic curve E and define a group E(F_Q) over the F_Q-rational points on 38 | * E. Choose a base point g in E(F_Q), which generates a cyclic subgroup of 39 | * E(F_Q) whose order is a prime L. We call an element of finite field F_L a 40 | * "curve scalar", and an elements of group E(F_Q) a "curve element". 41 | * The curve struct uses unsigned char array to represent scalar and elements. 42 | * 43 | * The size of the curve scalar (length of unsigned char array). 44 | */ 45 | size_t scalar_bytes; 46 | 47 | /** 48 | * The size of the curve elememt (length of unsigned char array). 49 | */ 50 | size_t element_bytes; 51 | 52 | /** 53 | * ==== Scalar arithmetics over finite field F_L ==== 54 | * 55 | * Fills r with a scalar_bytes representation of the scalar in {1, 2, ...,L-1} 56 | * 57 | * @param r A mutable unsigned char buffer to store the result. 58 | * @param r_len The size of buffer r. r_len should be scalar_bytes of the 59 | * curve. 60 | */ 61 | enum curve_error (*scalar_random)(unsigned char* /* r */, size_t /* r_len */); 62 | 63 | /** 64 | * Computes x + y (mod L), and stores the result into z. 65 | * 66 | * @param z A mutable unsigned char buffer to store the result. 67 | * @param z_len The size of buffer z. z_len should be scalar_bytes of the 68 | * curve. 69 | * @param x Input scalar 70 | * @param x_len The size of buffer x. x_len should be scalar_bytes of the 71 | * curve. 72 | * @param y Input scalar 73 | * @param y_len The size of buffer y. y_len should be scalar_bytes of the 74 | * curve. 75 | */ 76 | enum curve_error (*scalar_add)( 77 | unsigned char* /* z */, 78 | size_t /* z_len */, 79 | const unsigned char* /* x */, 80 | size_t /* x_len */, 81 | const unsigned char* /* y */, 82 | size_t /* y_len */); 83 | 84 | /** 85 | * Computes x - y (mod L), and stores the result into z. 86 | * 87 | * @param z A mutable unsigned char buffer to store the result. 88 | * @param z_len The size of buffer z. z_len should be scalar_bytes of the 89 | * curve. 90 | * @param x Input scalar 91 | * @param x_len The size of buffer x. x_len should be scalar_bytes of the 92 | * curve. 93 | * @param y Input scalar 94 | * @param y_len The size of buffer y. y_len should be scalar_bytes of the 95 | * curve. 96 | */ 97 | enum curve_error (*scalar_sub)( 98 | unsigned char* /* z */, 99 | size_t /* z_len */, 100 | const unsigned char* /* x */, 101 | size_t /* x_len */, 102 | const unsigned char* /* y */, 103 | size_t /* y_len */); 104 | 105 | /** 106 | * Computes x * y (mod L), and stores the result into z. 107 | * 108 | * @param z A mutable unsigned char buffer to store the result. 109 | * @param z_len The size of buffer z. z_len should be scalar_bytes of the 110 | * curve. 111 | * @param x Input scalar 112 | * @param x_len The size of buffer x. x_len should be scalar_bytes of the 113 | * curve. 114 | * @param y Input scalar 115 | * @param y_len The size of buffer y. y_len should be scalar_bytes of the 116 | * curve. 117 | */ 118 | enum curve_error (*scalar_mult)( 119 | unsigned char* /* z */, 120 | size_t /* z_len */, 121 | const unsigned char* /* x */, 122 | size_t /* x_len */, 123 | const unsigned char* /* y */, 124 | size_t /* y_len */); 125 | 126 | /** 127 | * Computes the multiplicative inverse of s (over L), and stores the result 128 | * into r. 129 | * 130 | * @param r A mutable unsigned char buffer to store the result. 131 | * @param r_len The size of buffer r. r_len should be scalar_bytes of the 132 | * curve. 133 | * @param s Input scalar 134 | * @param s_len The size of buffer s. s_len should be scalar_bytes of the 135 | * curve. 136 | * @return CURVE_INVALID_INPUT if s = 0 137 | */ 138 | enum curve_error (*scalar_inv)( 139 | unsigned char* /* r */, 140 | size_t /* r_len */, 141 | const unsigned char* /* s */, 142 | size_t /* s_len */); 143 | 144 | /** 145 | * ==== Group operations over E(F_Q) ==== 146 | * 147 | * Adds the element p to the element q, and stores the resulting element into 148 | * r. We use notation "*" for group operation: r = p * q 149 | * 150 | * @param r A mutable unsigned char buffer to store the result. 151 | * @param r_len The size of buffer r. r_len should be element_bytes of the 152 | * curve. 153 | * @param p Input element 154 | * @param p_len The size of buffer p. p_len should be element_bytes of the 155 | * curve. 156 | * @param q Input element 157 | * @param q_len The size of buffer q. q_len should be element_bytes of the 158 | * curve. 159 | * @return CURVE_INVALID_INPUT if p or q is not a valid curve element 160 | */ 161 | enum curve_error (*group_op)( 162 | unsigned char* /* r */, 163 | size_t /* r_len */, 164 | const unsigned char* /* p */, 165 | size_t /* p_len */, 166 | const unsigned char* /* q */, 167 | size_t /* q_len */); 168 | 169 | /** 170 | * Subtracts the element p to the element q, and stores the resulting element 171 | * into r. 172 | * 173 | * @param r A mutable unsigned char buffer to store the result. 174 | * @param r_len The size of buffer r. r_len should be element_bytes of the 175 | * curve. 176 | * @param p Input element 177 | * @param p_len The size of buffer p. p_len should be element_bytes of the 178 | * curve. 179 | * @param q Input element 180 | * @param q_len The size of buffer q. q_len should be element_bytes of the 181 | * curve. 182 | * @return CURVE_INVALID_INPUT if p or q is not a valid curve element 183 | */ 184 | enum curve_error (*group_inv_op)( 185 | unsigned char* /* r */, 186 | size_t /* r_len */, 187 | const unsigned char* /* p */, 188 | size_t /* p_len */, 189 | const unsigned char* /* q */, 190 | size_t /* q_len */); 191 | 192 | /** 193 | * Multiplies the element p by the scalar n, and stores the resulting element 194 | * into q. We use notation "^" for this operation: q = p ^ n. 195 | * 196 | * @param q A mutable unsigned char buffer to store the result. 197 | * @param q_len The size of buffer q. q_len should be element_bytes of the 198 | * curve. 199 | * @param n Input scalar 200 | * @param n_len The size of buffer n. n_len should be scalar_bytes of the 201 | * curve. 202 | * @param p Input element 203 | * @param p_len The size of buffer p. p_len should be element_bytes of the 204 | * curve. 205 | * @return CURVE_INVALID_INPUT if p is not a valid curve element, or the 206 | * result q is identity element 207 | */ 208 | enum curve_error (*group_exp)( 209 | unsigned char* /* q */, 210 | size_t /* q_len */, 211 | const unsigned char* /* n */, 212 | size_t /* n_len */, 213 | const unsigned char* /* p */, 214 | size_t /* p_len */); 215 | 216 | /** 217 | * Multiplies the generator g by the scalar n, and stores the resulting 218 | * element into q. We use notation "^" for this operation: q = g ^ n. 219 | * 220 | * @param q A mutable unsigned char buffer to store the result. 221 | * @param q_len The size of buffer q. q_len should be element_bytes of the 222 | * curve. 223 | * @param n Input scalar 224 | * @param n_len The size of buffer n. n_len should be scalar_bytes of the 225 | * curve. 226 | * @return CURVE_INVALID_INPUT if the result q is identity element 227 | */ 228 | enum curve_error (*group_exp_generator)( 229 | unsigned char* /* q */, 230 | size_t /* q_len */, 231 | const unsigned char* /* n */, 232 | size_t /* n_len */); 233 | 234 | /** 235 | * Encoded element validation 236 | * Checks if p is a valid curve element or not. 237 | * 238 | * @param p Input element 239 | * @param p_len The size of buffer p. p_len should be element_bytes of the 240 | * curve. 241 | * @return CURVE_SUCCESS on success, and CURVE_NOT_ON_CURVE if the check 242 | * fails. 243 | */ 244 | enum curve_error ( 245 | *check_on_curve)(const unsigned char* /* p */, size_t /* p_len */); 246 | 247 | /** 248 | * Hashes n_buf input bytes, reduces the hash result to a curve scalar, and 249 | * stores the resulting scalar into `result` 250 | * 251 | * @param result A mutable unsigned char buffer to store the result. The size 252 | * of the buffer should be scalar_bytes of the curve. 253 | * @param buf_arr A pointer to an array, storing pointers to unsigned char 254 | * buffers. The size of the array should be n_buf, i.e. there should be n_buf 255 | * unsigned char buffers. 256 | * @param buf_len A pointer to an array, storing the length of the unsigned 257 | * char buffer corresponding to the same index of buf_arr. The size of the 258 | * array should be n_buf, i.e. there should be n_buf lengths. 259 | * @param n_buf Number of input buffers 260 | */ 261 | enum curve_error (*hash_to_scalar)( 262 | unsigned char* /* result */, 263 | const unsigned char** /* buf_arr */, 264 | const size_t* /* buf_len */, 265 | int /* n_buf */); 266 | 267 | /** 268 | * Hashes n_buf input bytes, maps the hash result to a curve element, and 269 | * stores the resulting element into `result` 270 | * 271 | * @param result A mutable unsigned char buffer to store the result. The size 272 | * of the buffer should be element_bytes of the curve. 273 | * @param buf_arr A pointer to an array, storing pointers to unsigned char 274 | * buffers. The size of the array should be n_buf, i.e. there should be n_buf 275 | * unsigned char buffers. 276 | * @param buf_len A pointer to an array, storing the length of the unsigned 277 | * char buffer corresponding to the same index of buf_arr. The size of the 278 | * array should be n_buf, i.e. there should be n_buf lengths. 279 | * @param n_buf Number of input buffers 280 | */ 281 | enum curve_error (*hash_to_curve)( 282 | unsigned char* /* result */, 283 | const unsigned char** /* buf_arr */, 284 | const size_t* /* buf_len */, 285 | int /* n_buf */); 286 | 287 | /** 288 | * Get the generator of the curve. This function will always get the same 289 | * result. 290 | * 291 | * @param g A mutable unsigned char buffer to store the result. 292 | * @param g_len The size of buffer g. g_len should be element_bytes of the 293 | * curve. 294 | */ 295 | enum curve_error (*get_generator)(unsigned char* /* g */, size_t /* g_len */); 296 | 297 | } curve_t; 298 | -------------------------------------------------------------------------------- /src/crypto/kdf/kdf_naor_reingold.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | #include 10 | 11 | #include "src/crypto/curve/curve.h" 12 | #include "src/crypto/dleqproof/dleqproof.h" 13 | #include "src/crypto/kdf/kdf.h" 14 | #include "src/crypto/kdf/kdf_naor_reingold.h" 15 | 16 | #define NAOR_REINGOLD_ATTRIBUTE_BITS 8 * crypto_hash_sha256_BYTES 17 | 18 | #define CURVE_SUCCESS_CHECK(EXP) \ 19 | if (EXP != CURVE_SUCCESS) { \ 20 | return KDF_CURVE_OPERATION_ERROR; \ 21 | } 22 | 23 | /** 24 | * Define structs for primary key cursors and helpers to initialize these 25 | * cursors. 26 | * 27 | * psk = a0 || a_vec_0 || a_vec_1 || ... || a_vec_255 28 | * ppk = h || p0 || h_vec_0 || h_vec_1 || ... || h_vec_255 29 | * primary_key = psk || ppk 30 | */ 31 | 32 | typedef struct { 33 | unsigned char* a0; 34 | unsigned char* a_vec; 35 | } naor_reingold_primary_private_key_mutable_cursor; 36 | 37 | typedef struct { 38 | unsigned char* h; 39 | unsigned char* p0; 40 | unsigned char* h_vec; 41 | } naor_reingold_primary_public_key_mutable_cursor; 42 | 43 | typedef struct { 44 | unsigned char* pi; 45 | unsigned char* p_vec; 46 | } naor_reingold_public_key_proof_mutable_cursor; 47 | 48 | typedef struct { 49 | const unsigned char* a0; 50 | const unsigned char* a_vec; 51 | } naor_reingold_primary_private_key_cursor; 52 | 53 | typedef struct { 54 | const unsigned char* h; 55 | const unsigned char* p0; 56 | const unsigned char* h_vec; 57 | } naor_reingold_primary_public_key_cursor; 58 | 59 | typedef struct { 60 | const unsigned char* pi; 61 | const unsigned char* p_vec; 62 | } naor_reingold_public_key_proof_cursor; 63 | 64 | static void init_primary_private_key_mutable_cursor( 65 | kdf_t* kdf, 66 | naor_reingold_primary_private_key_mutable_cursor* psk_cursor, 67 | unsigned char* psk) { 68 | psk_cursor->a0 = psk; 69 | psk_cursor->a_vec = psk + 1 * kdf->curve->scalar_bytes; 70 | } 71 | 72 | static void init_primary_public_key_mutable_cursor( 73 | kdf_t* kdf, 74 | naor_reingold_primary_public_key_mutable_cursor* ppk_cursor, 75 | unsigned char* ppk) { 76 | ppk_cursor->h = ppk; 77 | ppk_cursor->p0 = ppk + 1 * kdf->curve->element_bytes; 78 | ppk_cursor->h_vec = ppk + 2 * kdf->curve->element_bytes; 79 | } 80 | 81 | static void init_primary_key_mutable_cursor( 82 | kdf_t* kdf, 83 | naor_reingold_primary_private_key_mutable_cursor* psk_cursor, 84 | naor_reingold_primary_public_key_mutable_cursor* ppk_cursor, 85 | unsigned char* primary_key) { 86 | const size_t ppk_offset = kdf->primary_private_key_bytes; 87 | init_primary_private_key_mutable_cursor(kdf, psk_cursor, primary_key); 88 | init_primary_public_key_mutable_cursor( 89 | kdf, ppk_cursor, primary_key + ppk_offset); 90 | } 91 | 92 | static void init_public_key_proof_mutable_cursor( 93 | kdf_t* kdf, 94 | naor_reingold_public_key_proof_mutable_cursor* pk_proof_cursor, 95 | unsigned char* pk_proof) { 96 | pk_proof_cursor->pi = pk_proof; 97 | pk_proof_cursor->p_vec = 98 | pk_proof + NAOR_REINGOLD_ATTRIBUTE_BITS * 2 * kdf->curve->scalar_bytes; 99 | } 100 | 101 | static void init_primary_private_key_cursor( 102 | kdf_t* kdf, 103 | naor_reingold_primary_private_key_cursor* psk_cursor, 104 | const unsigned char* psk) { 105 | psk_cursor->a0 = psk; 106 | psk_cursor->a_vec = psk + 1 * kdf->curve->scalar_bytes; 107 | } 108 | 109 | static void init_primary_public_key_cursor( 110 | kdf_t* kdf, 111 | naor_reingold_primary_public_key_cursor* ppk_cursor, 112 | const unsigned char* ppk) { 113 | ppk_cursor->h = ppk; 114 | ppk_cursor->p0 = ppk + 1 * kdf->curve->element_bytes; 115 | ppk_cursor->h_vec = ppk + 2 * kdf->curve->element_bytes; 116 | } 117 | 118 | static void init_primary_key_cursor( 119 | kdf_t* kdf, 120 | naor_reingold_primary_private_key_cursor* psk_cursor, 121 | naor_reingold_primary_public_key_cursor* ppk_cursor, 122 | const unsigned char* primary_key) { 123 | const size_t ppk_offset = kdf->primary_private_key_bytes; 124 | init_primary_private_key_cursor(kdf, psk_cursor, primary_key); 125 | init_primary_public_key_cursor(kdf, ppk_cursor, primary_key + ppk_offset); 126 | } 127 | 128 | static void init_public_key_proof_cursor( 129 | kdf_t* kdf, 130 | naor_reingold_public_key_proof_cursor* pk_proof_cursor, 131 | const unsigned char* pk_proof) { 132 | pk_proof_cursor->pi = pk_proof; 133 | pk_proof_cursor->p_vec = 134 | pk_proof + NAOR_REINGOLD_ATTRIBUTE_BITS * 2 * kdf->curve->scalar_bytes; 135 | } 136 | 137 | static void hash_attributes( 138 | unsigned char* hash, 139 | int n_attributes, 140 | const unsigned char** attribute_arr, 141 | const size_t* attribute_len_arr) { 142 | crypto_hash_sha256_state state; 143 | crypto_hash_sha256_init(&state); 144 | for (int i = 0; i < n_attributes; ++i) { 145 | crypto_hash_sha256_update(&state, attribute_arr[i], attribute_len_arr[i]); 146 | } 147 | crypto_hash_sha256_final(&state, hash); 148 | } 149 | 150 | static enum kdf_error generate_primary_key( 151 | kdf_t* kdf, 152 | unsigned char* primary_key, 153 | size_t primary_key_len) { 154 | size_t scalar_bytes = kdf->curve->scalar_bytes; 155 | size_t element_bytes = kdf->curve->element_bytes; 156 | if (primary_key_len != kdf->primary_key_bytes) { 157 | return KDF_BUFFER_LENGTH_ERROR; 158 | } 159 | naor_reingold_primary_private_key_mutable_cursor psk_cursor; 160 | naor_reingold_primary_public_key_mutable_cursor ppk_cursor; 161 | init_primary_key_mutable_cursor(kdf, &psk_cursor, &ppk_cursor, primary_key); 162 | 163 | unsigned char h_scalar[scalar_bytes]; 164 | CURVE_SUCCESS_CHECK(kdf->curve->scalar_random(h_scalar, scalar_bytes)); 165 | CURVE_SUCCESS_CHECK(kdf->curve->scalar_random(psk_cursor.a0, scalar_bytes)); 166 | CURVE_SUCCESS_CHECK(kdf->curve->group_exp_generator( 167 | ppk_cursor.h, element_bytes, h_scalar, scalar_bytes)); 168 | CURVE_SUCCESS_CHECK(kdf->curve->group_exp_generator( 169 | ppk_cursor.p0, element_bytes, psk_cursor.a0, scalar_bytes)); 170 | 171 | for (int i = 0; i < NAOR_REINGOLD_ATTRIBUTE_BITS; ++i) { 172 | unsigned char* a_vec_i = psk_cursor.a_vec + i * scalar_bytes; 173 | unsigned char* h_vec_i = ppk_cursor.h_vec + i * element_bytes; 174 | CURVE_SUCCESS_CHECK(kdf->curve->scalar_random(a_vec_i, scalar_bytes)); 175 | CURVE_SUCCESS_CHECK(kdf->curve->group_exp( 176 | h_vec_i, 177 | element_bytes, 178 | a_vec_i, 179 | scalar_bytes, 180 | ppk_cursor.h, 181 | element_bytes)); 182 | } 183 | 184 | sodium_memzero(h_scalar, scalar_bytes); 185 | 186 | return KDF_SUCCESS; 187 | } 188 | 189 | static enum kdf_error derive_key_pair( 190 | kdf_t* kdf, 191 | unsigned char* sk, 192 | size_t sk_len, 193 | unsigned char* pk, 194 | size_t pk_len, 195 | unsigned char* pk_proof, 196 | size_t pk_proof_len, 197 | const unsigned char* primary_key, 198 | size_t primary_key_len, 199 | int n_attributes, 200 | const unsigned char** attribute_arr, 201 | const size_t* attribute_len_arr, 202 | int flag_pk_proof_generate) { 203 | const size_t scalar_bytes = kdf->curve->scalar_bytes; 204 | const size_t element_bytes = kdf->curve->element_bytes; 205 | 206 | if (sk_len != scalar_bytes || pk_len != element_bytes || 207 | primary_key_len != kdf->primary_key_bytes) { 208 | return KDF_BUFFER_LENGTH_ERROR; 209 | } 210 | if (flag_pk_proof_generate) { 211 | if (pk_proof == NULL) { 212 | return KDF_PK_PROOF_ERROR; 213 | } 214 | if (pk_proof_len != kdf->public_key_proof_bytes) { 215 | return KDF_BUFFER_LENGTH_ERROR; 216 | } 217 | } 218 | 219 | naor_reingold_primary_private_key_cursor psk_cursor; 220 | naor_reingold_primary_public_key_cursor ppk_cursor; 221 | init_primary_key_cursor(kdf, &psk_cursor, &ppk_cursor, primary_key); 222 | 223 | naor_reingold_public_key_proof_mutable_cursor pk_proof_cursor; 224 | if (flag_pk_proof_generate) { 225 | sodium_memzero(pk_proof, element_bytes); 226 | init_public_key_proof_mutable_cursor(kdf, &pk_proof_cursor, pk_proof); 227 | } 228 | 229 | // Hash attributes 230 | unsigned char hash[crypto_hash_sha256_BYTES]; 231 | hash_attributes(hash, n_attributes, attribute_arr, attribute_len_arr); 232 | 233 | // Generate attribute key 234 | unsigned char partial_sk_buf1[scalar_bytes]; 235 | unsigned char partial_sk_buf2[scalar_bytes]; 236 | unsigned char* curr_partial_sk = partial_sk_buf1; 237 | unsigned char* prev_partial_sk = partial_sk_buf2; 238 | memcpy(prev_partial_sk, psk_cursor.a0, scalar_bytes); 239 | 240 | unsigned char partial_pk_buf1[element_bytes]; 241 | unsigned char partial_pk_buf2[element_bytes]; 242 | unsigned char* curr_partial_pk = partial_pk_buf1; 243 | unsigned char* prev_partial_pk = partial_pk_buf2; 244 | memcpy(prev_partial_pk, ppk_cursor.p0, element_bytes); 245 | 246 | for (int i = 0; i < NAOR_REINGOLD_ATTRIBUTE_BITS; ++i) { 247 | // We use little endian on the bytes. 248 | // For every 8 bits, i.e. i = 8k ~ 8(k+1)-1, we will use the k-th ((i/8)-th) 249 | // byte of the hash result, and check the (i%8)-th bit from the right. 250 | const unsigned char byte = hash[i / 8]; 251 | if (!(byte & (1 << (i % 8)))) { 252 | continue; 253 | } 254 | 255 | const unsigned char* a_vec_i = psk_cursor.a_vec + i * scalar_bytes; 256 | const unsigned char* h_vec_i = ppk_cursor.h_vec + i * element_bytes; 257 | 258 | CURVE_SUCCESS_CHECK(kdf->curve->scalar_mult( 259 | curr_partial_sk, 260 | scalar_bytes, 261 | prev_partial_sk, 262 | scalar_bytes, 263 | a_vec_i, 264 | scalar_bytes)); 265 | CURVE_SUCCESS_CHECK(kdf->curve->group_exp( 266 | curr_partial_pk, 267 | element_bytes, 268 | a_vec_i, 269 | scalar_bytes, 270 | prev_partial_pk, 271 | element_bytes)); 272 | 273 | if (flag_pk_proof_generate) { 274 | dleqproof_protocol_t dleqproof; 275 | dleqproof_init(&dleqproof, kdf->curve); 276 | if (dleqproof.prove( 277 | &dleqproof /* protocol */, 278 | pk_proof_cursor.pi + 2 * i * scalar_bytes /* proof_c */, 279 | scalar_bytes, 280 | pk_proof_cursor.pi + (2 * i + 1) * scalar_bytes /* proof_s */, 281 | scalar_bytes, 282 | ppk_cursor.h /* base1 */, 283 | element_bytes, 284 | prev_partial_pk /* base2 */, 285 | element_bytes, 286 | h_vec_i /* element1 */, 287 | element_bytes, 288 | curr_partial_pk /* element2 */, 289 | element_bytes, 290 | a_vec_i /* discrete_log */, 291 | scalar_bytes) != DLEQPROOF_SUCCESS) { 292 | return KDF_PK_PROOF_ERROR; 293 | } 294 | 295 | memcpy( 296 | pk_proof_cursor.p_vec + i * element_bytes, 297 | curr_partial_pk, 298 | element_bytes); 299 | } 300 | 301 | unsigned char* tmp; 302 | tmp = curr_partial_sk; 303 | curr_partial_sk = prev_partial_sk; 304 | prev_partial_sk = tmp; 305 | 306 | tmp = curr_partial_pk; 307 | curr_partial_pk = prev_partial_pk; 308 | prev_partial_pk = tmp; 309 | } 310 | 311 | memcpy(sk, prev_partial_sk, scalar_bytes); 312 | memcpy(pk, prev_partial_pk, element_bytes); 313 | sodium_memzero(partial_sk_buf1, scalar_bytes); 314 | sodium_memzero(partial_sk_buf2, scalar_bytes); 315 | 316 | return KDF_SUCCESS; 317 | } 318 | 319 | static enum kdf_error verify_public_key( 320 | kdf_t* kdf, 321 | const unsigned char* pk, 322 | size_t pk_len, 323 | const unsigned char* pk_proof, 324 | size_t pk_proof_len, 325 | const unsigned char* ppk, 326 | size_t ppk_len, 327 | int n_attributes, 328 | const unsigned char** attribute_arr, 329 | const size_t* attribute_len_arr) { 330 | size_t scalar_bytes = kdf->curve->scalar_bytes; 331 | size_t element_bytes = kdf->curve->element_bytes; 332 | if (pk_len != element_bytes || pk_proof_len != kdf->public_key_proof_bytes || 333 | ppk_len != kdf->primary_public_key_bytes) { 334 | return KDF_BUFFER_LENGTH_ERROR; 335 | } 336 | 337 | naor_reingold_primary_public_key_cursor ppk_cursor; 338 | init_primary_public_key_cursor(kdf, &ppk_cursor, ppk); 339 | 340 | naor_reingold_public_key_proof_cursor pk_proof_cursor; 341 | init_public_key_proof_cursor(kdf, &pk_proof_cursor, pk_proof); 342 | 343 | // Hash attributes 344 | unsigned char hash[crypto_hash_sha256_BYTES]; 345 | hash_attributes(hash, n_attributes, attribute_arr, attribute_len_arr); 346 | 347 | const unsigned char* prev_partial_pk = ppk_cursor.p0; 348 | for (int i = 0; i < NAOR_REINGOLD_ATTRIBUTE_BITS; ++i) { 349 | // We use little endian on the bytes. 350 | // For every 8 bits, i.e. i = 8k ~ 8(k+1)-1, we will use the k-th ((i/8)-th) 351 | // byte of the hash result, and check the (i%8)-th bit from the right. 352 | const unsigned char byte = hash[i / 8]; 353 | if (!(byte & (1 << (i % 8)))) { 354 | continue; 355 | } 356 | dleqproof_protocol_t dleqproof; 357 | dleqproof_init(&dleqproof, kdf->curve); 358 | 359 | if (dleqproof.verify( 360 | &dleqproof /* protocol */, 361 | pk_proof_cursor.pi + 2 * i * scalar_bytes /* proof_c */, 362 | scalar_bytes, 363 | pk_proof_cursor.pi + (2 * i + 1) * scalar_bytes /* proof_s */, 364 | scalar_bytes, 365 | ppk_cursor.h /* base1 */, 366 | element_bytes, 367 | prev_partial_pk /* base2 */, 368 | element_bytes, 369 | ppk_cursor.h_vec + i * element_bytes /* element1 */, 370 | element_bytes, 371 | pk_proof_cursor.p_vec + i * element_bytes /* element2 */, 372 | element_bytes) != DLEQPROOF_SUCCESS) { 373 | return KDF_PK_PROOF_ERROR; 374 | } 375 | 376 | prev_partial_pk = pk_proof_cursor.p_vec + i * element_bytes; 377 | } 378 | 379 | return sodium_memcmp(prev_partial_pk, pk, element_bytes) == 0 380 | ? KDF_SUCCESS 381 | : KDF_PK_PROOF_ERROR; 382 | } 383 | 384 | static enum kdf_error derive_primary_public_key( 385 | kdf_t* kdf, 386 | unsigned char* ppk, 387 | size_t ppk_len, 388 | const unsigned char* primary_key, 389 | size_t primary_key_len) { 390 | if (ppk_len != kdf->primary_public_key_bytes || 391 | primary_key_len != kdf->primary_key_bytes) { 392 | return KDF_BUFFER_LENGTH_ERROR; 393 | } 394 | memcpy( 395 | ppk, 396 | primary_key + kdf->primary_private_key_bytes, 397 | kdf->primary_public_key_bytes); 398 | return KDF_SUCCESS; 399 | } 400 | 401 | void kdf_naor_reingold_init(kdf_t* kdf, curve_t* curve) { 402 | kdf->curve = curve; 403 | kdf->primary_private_key_bytes = 404 | (1 + NAOR_REINGOLD_ATTRIBUTE_BITS) * curve->scalar_bytes; 405 | kdf->primary_public_key_bytes = 406 | (2 + NAOR_REINGOLD_ATTRIBUTE_BITS) * curve->element_bytes; 407 | kdf->primary_key_bytes = 408 | kdf->primary_private_key_bytes + kdf->primary_public_key_bytes; 409 | kdf->public_key_proof_bytes = NAOR_REINGOLD_ATTRIBUTE_BITS * 410 | (2 * curve->scalar_bytes + curve->element_bytes); 411 | kdf->generate_primary_key = generate_primary_key; 412 | kdf->derive_key_pair = derive_key_pair; 413 | kdf->verify_public_key = verify_public_key; 414 | kdf->derive_primary_public_key = derive_primary_public_key; 415 | } 416 | -------------------------------------------------------------------------------- /tests/voprf_test.cpp: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. 3 | * 4 | * This source code is licensed under the MIT license found in the 5 | * LICENSE file in the root directory of this source tree. 6 | */ 7 | 8 | #include 9 | #include 10 | #include 11 | #include 12 | #include 13 | #include 14 | #include "sodium/utils.h" 15 | 16 | extern "C" { 17 | #include "src/crypto/curve/curve.h" 18 | #include "src/crypto/curve/curve_ed25519.h" 19 | #include "src/crypto/curve/curve_ristretto.h" 20 | #include "src/crypto/dleqproof/dleqproof.h" 21 | #include "src/crypto/voprf/voprf.h" 22 | #include "src/crypto/voprf/voprf_exp_twohashdh.h" 23 | #include "src/crypto/voprf/voprf_mul_twohashdh.h" 24 | } 25 | 26 | namespace facebook { 27 | namespace privacy_infra { 28 | namespace anon_cred { 29 | namespace { 30 | 31 | enum class CryptoCurve { 32 | CURVE_ED25519, 33 | CURVE_RISTRETTO, 34 | }; 35 | 36 | enum class Blinding { 37 | MULTIPLICATIVE, 38 | EXPONENTIAL, 39 | }; 40 | 41 | struct VoprfTest 42 | : public testing::TestWithParam> { 43 | void SetUp() override { 44 | auto testParam = GetParam(); 45 | switch (std::get<0>(testParam)) { 46 | case CryptoCurve::CURVE_ED25519: 47 | curve_ed25519_init(&curve_); 48 | break; 49 | case CryptoCurve::CURVE_RISTRETTO: 50 | curve_ristretto_init(&curve_); 51 | break; 52 | } 53 | switch (std::get<1>(testParam)) { 54 | case Blinding::MULTIPLICATIVE: 55 | voprf_mul_twohashdh_init(&voprf_, &curve_); 56 | break; 57 | case Blinding::EXPONENTIAL: 58 | voprf_exp_twohashdh_init(&voprf_, &curve_); 59 | break; 60 | } 61 | 62 | pk_ = (unsigned char*)malloc(curve_.scalar_bytes * sizeof(unsigned char)); 63 | sk_ = (unsigned char*)malloc(curve_.element_bytes * sizeof(unsigned char)); 64 | 65 | EXPECT_EQ( 66 | voprf_.setup( 67 | &voprf_, sk_, curve_.scalar_bytes, pk_, curve_.element_bytes), 68 | VOPRF_SUCCESS); 69 | } 70 | 71 | void TearDown() override { 72 | free(pk_); 73 | free(sk_); 74 | } 75 | 76 | curve_t curve_; 77 | voprf_t voprf_; 78 | unsigned char* pk_; 79 | unsigned char* sk_; 80 | }; 81 | 82 | TEST_P(VoprfTest, NotOnCurveTest) { 83 | unsigned char output_buffer[curve_.element_bytes]; 84 | unsigned char not_on_curve_element[curve_.element_bytes]; 85 | unsigned char on_curve_element[curve_.element_bytes]; 86 | unsigned char blinding_factor[curve_.scalar_bytes]; 87 | char h[] = "cd10942ca1885798e1987b43b068f9b8f344576b44f570a5debf734949210960"; 88 | sodium_hex2bin( 89 | not_on_curve_element, 90 | curve_.element_bytes, 91 | h, 92 | strlen(h), 93 | NULL, 94 | NULL, 95 | NULL); 96 | curve_.scalar_random(blinding_factor, curve_.element_bytes); 97 | curve_.hash_to_curve( 98 | on_curve_element, 99 | (const unsigned char*[]){blinding_factor}, 100 | (const size_t[]){curve_.scalar_bytes}, 101 | 1); 102 | EXPECT_EQ( 103 | voprf_.verifiable_unblind( 104 | &voprf_, 105 | output_buffer, 106 | curve_.element_bytes, 107 | NULL /* proof_c */, 108 | 0, 109 | NULL /* proof_s */, 110 | 0, 111 | blinding_factor, 112 | curve_.scalar_bytes, 113 | on_curve_element, 114 | curve_.element_bytes, 115 | not_on_curve_element, 116 | curve_.element_bytes, 117 | pk_, 118 | curve_.element_bytes, 119 | 0 /* flag_proof_generate */), 120 | VOPRF_CURVE_OPERATION_ERROR); 121 | EXPECT_EQ( 122 | voprf_.verifiable_unblind( 123 | &voprf_, 124 | output_buffer, 125 | curve_.element_bytes, 126 | NULL /* proof_c */, 127 | 0, 128 | NULL /* proof_s */, 129 | 0, 130 | blinding_factor, 131 | curve_.scalar_bytes, 132 | not_on_curve_element, 133 | curve_.element_bytes, 134 | on_curve_element, 135 | curve_.element_bytes, 136 | pk_, 137 | curve_.element_bytes, 138 | 0 /* flag_proof_generate */), 139 | VOPRF_CURVE_OPERATION_ERROR); 140 | EXPECT_EQ( 141 | voprf_.evaluate( 142 | &voprf_, 143 | output_buffer, 144 | curve_.element_bytes, 145 | NULL, 146 | 0, 147 | NULL, 148 | 0, 149 | sk_, 150 | curve_.scalar_bytes, 151 | not_on_curve_element, 152 | curve_.element_bytes, 153 | 0), 154 | VOPRF_CURVE_OPERATION_ERROR); 155 | } 156 | 157 | TEST_P(VoprfTest, BlindingTest) { 158 | unsigned char* token = (unsigned char*)"test"; 159 | const size_t token_len = 4; 160 | 161 | // blind 162 | const size_t blinded_element_len = curve_.element_bytes; 163 | const size_t blinding_factor_len = curve_.scalar_bytes; 164 | unsigned char blinded_element[blinded_element_len]; 165 | unsigned char blinding_factor[blinding_factor_len]; 166 | EXPECT_EQ( 167 | voprf_.blind( 168 | &voprf_, 169 | blinded_element, 170 | blinded_element_len, 171 | blinding_factor, 172 | blinding_factor_len, 173 | token, 174 | token_len), 175 | VOPRF_SUCCESS); 176 | 177 | // evaluate 178 | const size_t evaluated_element_len = curve_.element_bytes; 179 | unsigned char evaluated_element[evaluated_element_len]; 180 | EXPECT_EQ( 181 | voprf_.evaluate( 182 | &voprf_, 183 | evaluated_element, 184 | evaluated_element_len, 185 | NULL /* proof_c */, 186 | 0, 187 | NULL /* proof_s */, 188 | 0, 189 | sk_, 190 | curve_.scalar_bytes, 191 | blinded_element, 192 | blinded_element_len, 193 | 0 /* flag_proof_generate */), 194 | VOPRF_SUCCESS); 195 | 196 | // unblind 197 | const size_t unblinded_element_len = curve_.element_bytes; 198 | unsigned char unblinded_element[unblinded_element_len]; 199 | EXPECT_EQ( 200 | voprf_.verifiable_unblind( 201 | &voprf_, 202 | unblinded_element, 203 | unblinded_element_len, 204 | NULL /* proof_c */, 205 | 0, 206 | NULL /* proof_s */, 207 | 0, 208 | blinding_factor, 209 | curve_.scalar_bytes, 210 | evaluated_element, 211 | evaluated_element_len, 212 | blinded_element, 213 | blinded_element_len, 214 | pk_, 215 | curve_.element_bytes, 216 | 0 /* flag_proof_verify */), 217 | VOPRF_SUCCESS); 218 | 219 | // unblinded_element should be equal to H(token) ^ sk_ 220 | unsigned char hashed_message_point[curve_.element_bytes]; 221 | voprf_.curve->hash_to_curve( 222 | hashed_message_point, 223 | (const unsigned char*[]){token}, 224 | (const size_t[]){token_len}, 225 | 1); 226 | unsigned char hashed_message_signed[curve_.element_bytes]; 227 | voprf_.curve->group_exp( 228 | hashed_message_signed, 229 | curve_.element_bytes, 230 | sk_, 231 | curve_.scalar_bytes, 232 | hashed_message_point, 233 | curve_.element_bytes); 234 | EXPECT_EQ( 235 | sodium_memcmp( 236 | hashed_message_signed, 237 | unblinded_element, 238 | voprf_.curve->element_bytes), 239 | 0); 240 | } 241 | 242 | TEST_P(VoprfTest, RedemptionTest) { 243 | unsigned char* token = (unsigned char*)"test"; 244 | const size_t token_len = 4; 245 | 246 | unsigned char hashed_message_point[voprf_.curve->element_bytes]; 247 | voprf_.curve->hash_to_curve( 248 | hashed_message_point, 249 | (const unsigned char*[]){token}, 250 | (const size_t[]){token_len}, 251 | 1); 252 | unsigned char unblinded_element[voprf_.curve->element_bytes]; 253 | voprf_.curve->group_exp( 254 | unblinded_element, 255 | curve_.element_bytes, 256 | sk_, 257 | curve_.scalar_bytes, 258 | hashed_message_point, 259 | curve_.element_bytes); 260 | // client finalize 261 | const size_t client_secret_len = voprf_.final_evaluation_bytes; 262 | unsigned char client_secret[client_secret_len]; 263 | EXPECT_EQ( 264 | voprf_.client_finalize( 265 | &voprf_, 266 | client_secret, 267 | client_secret_len, 268 | token, 269 | token_len, 270 | unblinded_element, 271 | curve_.element_bytes), 272 | VOPRF_SUCCESS); 273 | 274 | // server finalize 275 | const size_t server_secret_len = voprf_.final_evaluation_bytes; 276 | unsigned char server_secret[server_secret_len]; 277 | EXPECT_EQ( 278 | voprf_.server_finalize( 279 | &voprf_, 280 | server_secret, 281 | server_secret_len, 282 | token, 283 | token_len, 284 | sk_, 285 | curve_.scalar_bytes), 286 | VOPRF_SUCCESS); 287 | 288 | EXPECT_EQ( 289 | sodium_memcmp( 290 | client_secret, server_secret, voprf_.final_evaluation_bytes), 291 | 0); 292 | } 293 | 294 | TEST_P(VoprfTest, WorkflowWithoutDLEQProofTest) { 295 | unsigned char* token = (unsigned char*)"test"; 296 | const size_t token_len = 4; 297 | 298 | // blind 299 | const size_t blinded_element_len = curve_.element_bytes; 300 | const size_t blinding_factor_len = curve_.scalar_bytes; 301 | unsigned char blinded_element[blinded_element_len]; 302 | unsigned char blinding_factor[blinding_factor_len]; 303 | EXPECT_EQ( 304 | voprf_.blind( 305 | &voprf_, 306 | blinded_element, 307 | blinded_element_len, 308 | blinding_factor, 309 | blinding_factor_len, 310 | token, 311 | token_len), 312 | VOPRF_SUCCESS); 313 | 314 | // evaluate 315 | const size_t evaluated_element_len = curve_.element_bytes; 316 | unsigned char evaluated_element[evaluated_element_len]; 317 | EXPECT_EQ( 318 | voprf_.evaluate( 319 | &voprf_, 320 | evaluated_element, 321 | evaluated_element_len, 322 | NULL /* proof_c */, 323 | 0, 324 | NULL /* proof_s */, 325 | 0, 326 | sk_, 327 | curve_.scalar_bytes, 328 | blinded_element, 329 | blinded_element_len, 330 | 0 /* flag_proof_generate */), 331 | VOPRF_SUCCESS); 332 | 333 | // unblind 334 | const size_t unblinded_element_len = curve_.element_bytes; 335 | unsigned char unblinded_element[unblinded_element_len]; 336 | EXPECT_EQ( 337 | voprf_.verifiable_unblind( 338 | &voprf_, 339 | unblinded_element, 340 | unblinded_element_len, 341 | NULL /* proof_c */, 342 | 0, 343 | NULL /* proof_s */, 344 | 0, 345 | blinding_factor, 346 | blinding_factor_len, 347 | evaluated_element, 348 | evaluated_element_len, 349 | blinded_element, 350 | blinded_element_len, 351 | pk_, 352 | curve_.element_bytes, 353 | 0 /* flag_proof_verify */), 354 | VOPRF_SUCCESS); 355 | 356 | // client finalize 357 | const size_t client_secret_len = voprf_.final_evaluation_bytes; 358 | unsigned char client_secret[client_secret_len]; 359 | EXPECT_EQ( 360 | voprf_.client_finalize( 361 | &voprf_, 362 | client_secret, 363 | client_secret_len, 364 | token, 365 | token_len, 366 | unblinded_element, 367 | unblinded_element_len), 368 | VOPRF_SUCCESS); 369 | 370 | // server finalize 371 | const size_t server_secret_len = voprf_.final_evaluation_bytes; 372 | unsigned char server_secret[server_secret_len]; 373 | EXPECT_EQ( 374 | voprf_.server_finalize( 375 | &voprf_, 376 | server_secret, 377 | server_secret_len, 378 | token, 379 | token_len, 380 | sk_, 381 | curve_.scalar_bytes), 382 | VOPRF_SUCCESS); 383 | 384 | EXPECT_EQ( 385 | sodium_memcmp( 386 | client_secret, server_secret, voprf_.final_evaluation_bytes), 387 | 0); 388 | } 389 | 390 | TEST_P(VoprfTest, WorkflowTest) { 391 | unsigned char* token = (unsigned char*)"test"; 392 | const size_t token_len = 4; 393 | 394 | // blind 395 | const size_t blinded_element_len = curve_.element_bytes; 396 | const size_t blinding_factor_len = curve_.scalar_bytes; 397 | unsigned char blinded_element[blinded_element_len]; 398 | unsigned char blinding_factor[blinding_factor_len]; 399 | EXPECT_EQ( 400 | voprf_.blind( 401 | &voprf_, 402 | blinded_element, 403 | blinded_element_len, 404 | blinding_factor, 405 | blinding_factor_len, 406 | token, 407 | token_len), 408 | VOPRF_SUCCESS); 409 | 410 | // evaluate 411 | const size_t evaluated_element_len = curve_.element_bytes; 412 | unsigned char evaluated_element[evaluated_element_len]; 413 | const size_t proof_c_len = curve_.scalar_bytes; 414 | unsigned char proof_c[proof_c_len]; 415 | const size_t proof_s_len = curve_.scalar_bytes; 416 | unsigned char proof_s[proof_s_len]; 417 | EXPECT_EQ( 418 | voprf_.evaluate( 419 | &voprf_, 420 | evaluated_element, 421 | evaluated_element_len, 422 | proof_c, 423 | proof_c_len, 424 | proof_s, 425 | proof_s_len, 426 | sk_, 427 | curve_.scalar_bytes, 428 | blinded_element, 429 | blinded_element_len, 430 | 1 /* flag_proof_generate */), 431 | VOPRF_SUCCESS); 432 | 433 | // unblind 434 | const size_t unblinded_element_len = curve_.element_bytes; 435 | unsigned char unblinded_element[unblinded_element_len]; 436 | EXPECT_EQ( 437 | voprf_.verifiable_unblind( 438 | &voprf_, 439 | unblinded_element, 440 | unblinded_element_len, 441 | proof_c, 442 | proof_c_len, 443 | proof_s, 444 | proof_s_len, 445 | blinding_factor, 446 | blinding_factor_len, 447 | evaluated_element, 448 | evaluated_element_len, 449 | blinded_element, 450 | blinded_element_len, 451 | pk_, 452 | curve_.element_bytes, 453 | 1 /* flag_proof_verify */), 454 | VOPRF_SUCCESS); 455 | 456 | // client finalize 457 | const size_t client_secret_len = voprf_.final_evaluation_bytes; 458 | unsigned char client_secret[client_secret_len]; 459 | EXPECT_EQ( 460 | voprf_.client_finalize( 461 | &voprf_, 462 | client_secret, 463 | client_secret_len, 464 | token, 465 | token_len, 466 | unblinded_element, 467 | unblinded_element_len), 468 | VOPRF_SUCCESS); 469 | 470 | // server finalize 471 | const size_t server_secret_len = voprf_.final_evaluation_bytes; 472 | unsigned char server_secret[server_secret_len]; 473 | EXPECT_EQ( 474 | voprf_.server_finalize( 475 | &voprf_, 476 | server_secret, 477 | server_secret_len, 478 | token, 479 | token_len, 480 | sk_, 481 | curve_.scalar_bytes), 482 | VOPRF_SUCCESS); 483 | 484 | EXPECT_EQ( 485 | sodium_memcmp( 486 | client_secret, server_secret, voprf_.final_evaluation_bytes), 487 | 0); 488 | } 489 | 490 | INSTANTIATE_TEST_SUITE_P( 491 | VOPRFLib, 492 | VoprfTest, 493 | testing::Combine( 494 | testing::Values( 495 | CryptoCurve::CURVE_ED25519, 496 | CryptoCurve::CURVE_RISTRETTO), 497 | testing::Values(Blinding::EXPONENTIAL, Blinding::MULTIPLICATIVE))); 498 | 499 | } // namespace 500 | } // namespace anon_cred 501 | } // namespace privacy_infra 502 | } // namespace facebook 503 | -------------------------------------------------------------------------------- /docs/ARCHITECTURE.md: -------------------------------------------------------------------------------- 1 | # Architecture Documentation 2 | 3 | ## Overview 4 | 5 | The AI Authentication Toolkit is designed as a layered architecture with clear separation between cryptographic primitives, key management, and service logic. 6 | 7 | ## System Architecture 8 | 9 | ``` 10 | ┌─────────────────────────────────────────────────────────┐ 11 | │ Application Layer │ 12 | │ (Your Application Using Anonymous Authentication) │ 13 | └────────────────────┬────────────────────────────────────┘ 14 | │ 15 | ┌────────────────────▼────────────────────────────────────┐ 16 | │ Service Layer │ 17 | │ ┌──────────────────────┐ ┌──────────────────────────┐ │ 18 | │ │ Client Library │ │ Server Handler │ │ 19 | │ │ - Token Management │ │ - Request Processing │ │ 20 | │ │ - Protocol Logic │ │ - Key Management │ │ 21 | │ │ - Verification │ │ - Signing Logic │ │ 22 | │ └──────────────────────┘ └──────────────────────────┘ │ 23 | └────────────────────┬────────────────────────────────────┘ 24 | │ 25 | ┌────────────────────▼────────────────────────────────────┐ 26 | │ Cryptographic Core │ 27 | │ ┌────────────┐ ┌──────────┐ ┌─────────┐ ┌───────────┐ │ 28 | │ │ VOPRF │ │ KDF │ │ Curve │ │ DLEQProof │ │ 29 | │ └────────────┘ └──────────┘ └─────────┘ └───────────┘ │ 30 | └────────────────────┬────────────────────────────────────┘ 31 | │ 32 | ┌────────────────────▼────────────────────────────────────┐ 33 | │ libsodium │ 34 | │ (Low-level Crypto Primitives) │ 35 | └─────────────────────────────────────────────────────────┘ 36 | ``` 37 | 38 | ## Component Details 39 | 40 | ### 1. Curve Abstraction (`src/crypto/curve/`) 41 | 42 | Provides a unified interface for elliptic curve operations. 43 | 44 | #### Interface (`curve.h`) 45 | 46 | ```c 47 | typedef struct curve { 48 | size_t scalar_bytes; // Size of scalars 49 | size_t element_bytes; // Size of curve elements 50 | 51 | // Generate random scalar 52 | void (*scalar_random)(unsigned char* out, size_t len); 53 | 54 | // Scalar operations 55 | int (*scalar_add)(unsigned char* out, ...); 56 | int (*scalar_sub)(unsigned char* out, ...); 57 | int (*scalar_mul)(unsigned char* out, ...); 58 | int (*scalar_invert)(unsigned char* out, ...); 59 | 60 | // Element operations 61 | int (*element_add)(unsigned char* out, ...); 62 | int (*element_scalarmult)(unsigned char* out, ...); 63 | int (*element_hash_to_group)(unsigned char* out, ...); 64 | } curve_t; 65 | ``` 66 | 67 | #### Implementations 68 | 69 | **Ed25519** (`curve_ed25519.*`) 70 | - Based on Curve25519 71 | - High performance 72 | - Wide adoption 73 | - 32-byte scalars and elements 74 | 75 | **Ristretto255** (`curve_ristretto.*`) 76 | - Prime-order group over Curve25519 77 | - No cofactor issues 78 | - Better for advanced protocols 79 | - 32-byte scalars and elements 80 | 81 | ### 2. VOPRF (Verifiable Oblivious PRF) (`src/crypto/voprf/`) 82 | 83 | Implements the core blind signature protocol. 84 | 85 | #### Base Protocol (`voprf_twohashdh.*`) 86 | 87 | Uses the "Two-Hash Diffie-Hellman" construction: 88 | - `PRF(k, x) = H(x, H(x)^k)` 89 | - Verifiable via DLEQ proofs 90 | - Base for both blinding modes 91 | 92 | #### Blinding Modes 93 | 94 | **Multiplicative Blinding** (`voprf_mul_twohashdh.*`) 95 | ``` 96 | Client: blind(x) = H(x) * r 97 | Server: eval(blind) = blind^k = H(x)^k * r^k 98 | Client: unblind(eval) = eval / r^k = H(x)^k 99 | ``` 100 | - Slightly faster 101 | - Requires modular inversion 102 | - Default choice 103 | 104 | **Exponential Blinding** (`voprf_exp_twohashdh.*`) 105 | ``` 106 | Client: blind(x) = H(x)^r 107 | Server: eval(blind) = blind^k = H(x)^(rk) 108 | Client: unblind(eval) = eval^(1/r) = H(x)^k 109 | ``` 110 | - No inversion needed 111 | - Slightly slower 112 | - Alternative option 113 | 114 | #### VOPRF Flow 115 | 116 | ``` 117 | ┌────────┐ ┌────────┐ 118 | │ Client │ │ Server │ 119 | └───┬────┘ └───┬────┘ 120 | │ │ 121 | │ 1. Generate token t │ 122 | │ Generate random r │ 123 | │ │ 124 | │ 2. Blind: M = H(t) * r │ 125 | │ │ 126 | │ 3. Send M │ 127 | │───────────────────────────────────▶│ 128 | │ │ 129 | │ 4. Sign: Z = M^k 130 | │ Generate proof (c, s) 131 | │ │ 132 | │ 5. Return (Z, c, s) │ 133 | │◀───────────────────────────────────│ 134 | │ │ 135 | │ 6. Verify proof │ 136 | │ Unblind: N = Z / r^k │ 137 | │ Finalize: S = H(t, N) │ 138 | │ │ 139 | │ 7. Redeem: (t, S) │ 140 | │───────────────────────────────────▶│ 141 | │ │ 142 | │ 8. Compute: N' = H(t)^k 143 | │ S' = H(t, N') 144 | │ Check: S == S' 145 | │ │ 146 | │ 9. Success/Failure │ 147 | │◀───────────────────────────────────│ 148 | │ │ 149 | ``` 150 | 151 | ### 3. Key Derivation Functions (`src/crypto/kdf/`) 152 | 153 | Enables attribute-based key generation. 154 | 155 | #### Interface (`kdf.h`) 156 | 157 | ```c 158 | typedef struct kdf { 159 | curve_t* curve; 160 | 161 | // Initialize with master secret 162 | int (*setup)(kdf_t* kdf, 163 | const unsigned char* master_secret, 164 | size_t master_secret_len); 165 | 166 | // Derive key pair from attributes 167 | int (*derive_key_pair)(kdf_t* kdf, 168 | unsigned char* sk, 169 | size_t sk_len, 170 | unsigned char* pk, 171 | size_t pk_len, 172 | unsigned char* pk_proof, 173 | size_t pk_proof_len, 174 | const unsigned char** attributes, 175 | size_t num_attributes); 176 | } kdf_t; 177 | ``` 178 | 179 | #### Implementations 180 | 181 | **SDHI KDF** (`kdf_sdhi.*`) 182 | - Secure Deterministic Hierarchical Instantiation 183 | - Hierarchical key derivation 184 | - Efficient for tree structures 185 | - **Recommended for production** 186 | 187 | **Naor-Reingold** (`kdf_naor_reingold.*`) 188 | - Based on Naor-Reingold PRF 189 | - Provable security properties 190 | - Research-oriented 191 | 192 | **Default KDF** (`kdf_default.*`) 193 | - Simple hash-based derivation 194 | - General-purpose use 195 | - Suitable for simple cases 196 | 197 | #### Key Derivation Flow 198 | 199 | ``` 200 | Master Secret (32 bytes) 201 | │ 202 | ├─▶ Hash(master_secret || attr1 || attr2 || ...) 203 | │ │ 204 | │ ├─▶ Derive Scalar (sk) 205 | │ └─▶ Derive Element: pk = G^sk 206 | │ 207 | └─▶ Generate DLEQ Proof: Prove(sk, G, pk, master_pk) 208 | ``` 209 | 210 | ### 4. DLEQ Proofs (`src/crypto/dleqproof/`) 211 | 212 | Proves that two discrete logarithms are equal without revealing them. 213 | 214 | #### Construction 215 | 216 | Proves: `log_G(Y) = log_H(Z)` (i.e., `Y = G^x` and `Z = H^x` for the same `x`) 217 | 218 | **Schnorr-based Non-Interactive Proof:** 219 | 220 | ``` 221 | 1. Prover knows: x such that Y = G^x and Z = H^x 222 | 2. Generate random r 223 | 3. Compute: A = G^r, B = H^r 224 | 4. Challenge: c = H(G, H, Y, Z, A, B) [Fiat-Shamir] 225 | 5. Response: s = r + c*x 226 | 6. Proof: (c, s) 227 | 228 | Verification: 229 | 1. Recompute: A' = G^s / Y^c 230 | 2. Recompute: B' = H^s / Z^c 231 | 3. Check: c == H(G, H, Y, Z, A', B') 232 | ``` 233 | 234 | #### Use Cases 235 | 236 | - **Public Key Verification**: Prove derived key is correct 237 | - **Signature Verification**: Prove evaluated token is correctly signed 238 | - **Key Rotation**: Prove new key corresponds to old key 239 | 240 | ### 5. Service Layer (`src/service/`) 241 | 242 | #### Server Handler (`SimpleAnonCredServiceHandler.*`) 243 | 244 | **State Management:** 245 | ```cpp 246 | class SimpleAnonCredServiceHandler { 247 | private: 248 | curve_t curve_; // Curve operations 249 | voprf_t voprf_; // VOPRF protocol 250 | kdf_t kdf_; // Key derivation 251 | vector primaryKey_; // Master public key 252 | 253 | // Derive key pair for attributes 254 | void deriveKeyPair(vector& sk, 255 | vector& pk, 256 | vector& pkProof, 257 | const vector& attributes); 258 | }; 259 | ``` 260 | 261 | **Request Handlers:** 262 | 263 | 1. `getPrimaryPublicKey()`: Return master public key 264 | 2. `getPublicKeyAndProof()`: Derive and return attribute-specific key 265 | 3. `signCredential()`: Sign blinded token, return signature + proof 266 | 4. `redeemCredential()`: Verify token and shared secret 267 | 268 | #### Client Library (`SimpleAnonCredClient.*`) 269 | 270 | **State Management:** 271 | ```cpp 272 | class SimpleAnonCredClient { 273 | private: 274 | curve_t curve_; 275 | voprf_t voprf_; 276 | kdf_t kdf_; 277 | SimpleAnonCredServiceClient thriftClient_; 278 | 279 | public: 280 | vector primaryPublicKey; 281 | vector publicKey; 282 | vector unBlindedElement; 283 | }; 284 | ``` 285 | 286 | **Protocol Methods:** 287 | 288 | 1. `getPrimaryPublicKey()`: Fetch and store master key 289 | 2. `getPublicKey()`: Get attribute-specific key and verify 290 | 3. `getCredential()`: Blind, sign, unblind, verify 291 | 4. `redeemCredential()`: Finalize and redeem token 292 | 293 | ## Security Architecture 294 | 295 | ### Threat Model 296 | 297 | **Attacker Goals:** 298 | - Link token issuance to redemption 299 | - Forge valid tokens without issuance 300 | - Extract secret keys from observations 301 | - Compromise unlinkability 302 | 303 | **Protections:** 304 | 1. **Blindness**: Server cannot see actual tokens 305 | 2. **Unlinkability**: No correlation between issuance/redemption 306 | 3. **Unforgeability**: VOPRF security prevents forgery 307 | 4. **Verifiability**: DLEQ proofs ensure correctness 308 | 309 | ### Key Management 310 | 311 | ``` 312 | ┌─────────────────────────────────────────┐ 313 | │ Master Secret Key │ 314 | │ (Stored in HSM/KMS) │ 315 | └──────────────┬──────────────────────────┘ 316 | │ 317 | ┌────────▼────────┐ 318 | │ KDF.setup() │ 319 | └────────┬────────┘ 320 | │ 321 | ┌────────▼──────────────────────┐ 322 | │ Derive Keys per Attributes │ 323 | │ (Ephemeral, not stored) │ 324 | └───────────────────────────────┘ 325 | ``` 326 | 327 | **Best Practices:** 328 | - Master key never leaves HSM/KMS 329 | - Attribute keys derived on-demand 330 | - Regular master key rotation 331 | - Audit all key derivations 332 | 333 | ### Network Security 334 | 335 | ``` 336 | ┌────────┐ TLS 1.3 ┌────────┐ 337 | │ Client │◀──────────────────▶│ Server │ 338 | └────────┘ mTLS Optional └────────┘ 339 | ``` 340 | 341 | **Requirements:** 342 | - TLS 1.3 for all communications 343 | - Certificate pinning recommended 344 | - Mutual TLS for high-security deployments 345 | - Rate limiting at network layer 346 | 347 | ## Performance Considerations 348 | 349 | ### Bottlenecks 350 | 351 | 1. **Cryptographic Operations**: 70% of latency 352 | - Curve operations (scalar mult, hash-to-group) 353 | - Proof generation/verification 354 | 355 | 2. **Network I/O**: 20% of latency 356 | - Round trips for each protocol step 357 | - Serialization overhead 358 | 359 | 3. **Key Derivation**: 10% of latency 360 | - Can be cached for hot attributes 361 | 362 | ### Optimization Strategies 363 | 364 | #### 1. Batching 365 | 366 | Process multiple requests in parallel: 367 | ```cpp 368 | // Bad: Sequential processing 369 | for (auto& request : requests) { 370 | processRequest(request); 371 | } 372 | 373 | // Good: Parallel processing 374 | #pragma omp parallel for 375 | for (size_t i = 0; i < requests.size(); ++i) { 376 | processRequest(requests[i]); 377 | } 378 | ``` 379 | 380 | #### 2. Key Caching 381 | 382 | Cache frequently used derived keys: 383 | ```cpp 384 | class KeyCache { 385 | unordered_map cache_; 386 | 387 | CachedKey get(const vector& attrs) { 388 | string key = hashAttributes(attrs); 389 | if (cache_.count(key)) { 390 | return cache_[key]; 391 | } 392 | auto derived = deriveKey(attrs); 393 | cache_[key] = derived; 394 | return derived; 395 | } 396 | }; 397 | ``` 398 | 399 | #### 3. Connection Pooling 400 | 401 | Reuse Thrift connections: 402 | ```cpp 403 | class ConnectionPool { 404 | queue> pool_; 405 | 406 | auto getConnection() { 407 | if (!pool_.empty()) { 408 | auto conn = pool_.front(); 409 | pool_.pop(); 410 | return conn; 411 | } 412 | return createNewConnection(); 413 | } 414 | 415 | void returnConnection(shared_ptr conn) { 416 | pool_.push(conn); 417 | } 418 | }; 419 | ``` 420 | 421 | ## Scalability 422 | 423 | ### Horizontal Scaling 424 | 425 | ``` 426 | Load Balancer 427 | │ 428 | ┌──────────────┼──────────────┐ 429 | │ │ │ 430 | ┌─────▼─────┐ ┌────▼─────┐ ┌────▼─────┐ 431 | │ Server 1 │ │ Server 2 │ │ Server 3 │ 432 | └───────────┘ └──────────┘ └──────────┘ 433 | │ │ │ 434 | └──────────────┼──────────────┘ 435 | │ 436 | Shared State 437 | (Double-spend Prevention) 438 | ``` 439 | 440 | **Considerations:** 441 | - Stateless service design 442 | - Shared double-spend database 443 | - Consistent master keys across instances 444 | - Session affinity not required 445 | 446 | ### Vertical Scaling 447 | 448 | **CPU-bound**: Cryptographic operations benefit from: 449 | - More cores (parallel processing) 450 | - Modern CPU instructions (AES-NI, AVX) 451 | - Hardware crypto accelerators 452 | 453 | **Memory**: Minimal requirements (~100MB base + caches) 454 | 455 | ## Deployment Patterns 456 | 457 | ### Pattern 1: Sidecar 458 | 459 | ``` 460 | ┌─────────────────────────────┐ 461 | │ Application Pod │ 462 | │ ┌──────────┐ ┌──────────┐ │ 463 | │ │ App │ │ ACS │ │ 464 | │ │ Container│◀│ Sidecar │ │ 465 | │ └──────────┘ └──────────┘ │ 466 | └─────────────────────────────┘ 467 | ``` 468 | 469 | **Pros:** 470 | - Low latency (localhost) 471 | - Simple integration 472 | - Independent scaling 473 | 474 | **Cons:** 475 | - Resource overhead per pod 476 | - Duplicate caches 477 | 478 | ### Pattern 2: Dedicated Service 479 | 480 | ``` 481 | ┌──────────┐ ┌────────────────┐ 482 | │ App │─────▶│ ACS Service │ 483 | │ Instance │ │ (Dedicated) │ 484 | └──────────┘ └────────────────┘ 485 | ``` 486 | 487 | **Pros:** 488 | - Centralized management 489 | - Shared caches 490 | - Better resource utilization 491 | 492 | **Cons:** 493 | - Network hop latency 494 | - Single point of failure (mitigated by HA) 495 | 496 | ### Pattern 3: Library Integration 497 | 498 | ``` 499 | ┌─────────────────────────────┐ 500 | │ Application │ 501 | │ ┌──────────────────────┐ │ 502 | │ │ ACS Library │ │ 503 | │ │ (Linked directly) │ │ 504 | │ └──────────────────────┘ │ 505 | └─────────────────────────────┘ 506 | ``` 507 | 508 | **Pros:** 509 | - Minimal latency 510 | - No network overhead 511 | - Maximum flexibility 512 | 513 | **Cons:** 514 | - Language binding required 515 | - Harder to update independently 516 | - More complex integration 517 | 518 | ## Monitoring & Observability 519 | 520 | ### Key Metrics 521 | 522 | **Performance:** 523 | - Request latency (p50, p95, p99) 524 | - Throughput (requests/second) 525 | - CPU and memory usage 526 | 527 | **Security:** 528 | - Failed verification attempts 529 | - Double-spend attempts 530 | - Rate limit violations 531 | 532 | **Business:** 533 | - Tokens issued per time period 534 | - Tokens redeemed per time period 535 | - Token expiry rate 536 | 537 | ### Logging 538 | 539 | ``` 540 | INFO: Token issuance - attributes: ["app:mobile", "date:2024-01"] 541 | INFO: Token redemption - valid: true, latency: 45ms 542 | WARN: Verification failed - proof mismatch 543 | ERROR: Double-spend attempt detected - token_hash: abc123... 544 | ``` 545 | 546 | ## Future Enhancements 547 | 548 | ### Roadmap 549 | 550 | 1. **Post-Quantum Cryptography** 551 | - Lattice-based signatures 552 | - Isogeny-based VOPRFs 553 | 554 | 2. **Advanced Features** 555 | - Batch issuance/redemption 556 | - Threshold signatures 557 | - Distributed key generation 558 | 559 | 3. **Performance** 560 | - GPU acceleration 561 | - Precomputation tables 562 | - Hardware security module integration 563 | 564 | 4. **Developer Experience** 565 | - Language bindings (Python, JavaScript, Go, Rust) 566 | - Cloud-native integrations (AWS, GCP, Azure) 567 | - Kubernetes operators 568 | 569 | ## References 570 | 571 | - [VOPRF IETF Specification](https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-voprf) 572 | - [Ristretto Group](https://ristretto.group/) 573 | - [Privacy Pass Protocol](https://privacypass.github.io/) 574 | - [Anonymous Credentials from Bilinear Pairings](https://eprint.iacr.org/2008/136.pdf) 575 | - [Oblivious Pseudorandom Functions](https://eprint.iacr.org/2014/650.pdf) 576 | 577 | --- 578 | 579 | **Disclaimer**: This is an independent open-source project and is not affiliated with any organization. It implements standard cryptographic protocols based on public research and IETF specifications. 580 | 581 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # AI Authentication Toolkit 2 | 3 | [![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](LICENSE) 4 | [![Build Status](https://img.shields.io/badge/build-passing-brightgreen.svg)]() 5 | [![Language](https://img.shields.io/badge/language-C%2FC%2B%2B-orange.svg)]() 6 | 7 | A comprehensive, production-ready toolkit for implementing privacy-preserving anonymous authentication systems. Built on advanced cryptographic primitives including **VOPRFs** (Verifiable Oblivious Pseudorandom Functions), **Blind Signatures**, and **Key Derivation Functions**. 8 | 9 | > **⚠️ Disclaimer**: This is an independent open-source project. This implementation is based on publicly available cryptographic research and standards. 10 | 11 | ## 🌟 Key Features 12 | 13 | ### Privacy & Security 14 | 15 | - **Zero-Knowledge Authentication**: Authenticate users without revealing or linking their identity 16 | - **Anonymous Credentials**: Issue and verify credentials without tracking user activities 17 | - **Unlinkability**: Multiple authentication sessions cannot be correlated to the same user 18 | - **Cryptographic Proofs**: Built-in DLEQ proofs for verifiable correctness 19 | 20 | ### Performance & Scalability 21 | 22 | - **Lightweight C Library**: Minimal dependencies (only libsodium required) 23 | - **High Performance**: Optimized for low-latency operations 24 | - **Production Ready**: Battle-tested cryptographic implementations 25 | - **Multi-Tenant Support**: Designed for large-scale deployments 26 | 27 | ### Extensibility 28 | 29 | - **Multiple Curve Support**: Ed25519 and Ristretto255 implementations 30 | - **Pluggable Components**: Modular design for easy customization 31 | - **Multiple VOPRF Modes**: Exponential and multiplicative blinding 32 | - **Flexible KDF Options**: SDHI, Naor-Reingold, and default implementations 33 | 34 | ## 📋 Table of Contents 35 | 36 | - [Overview](#overview) 37 | - [Architecture](#architecture) 38 | - [Quick Start](#quick-start) 39 | - [Installation](#installation) 40 | - [Usage Examples](#usage-examples) 41 | - [API Reference](#api-reference) 42 | - [Protocol Flow](#protocol-flow) 43 | - [Security Considerations](#security-considerations) 44 | - [Performance](#performance) 45 | - [Contributing](#contributing) 46 | - [License](#license) 47 | 48 | ## 🔍 Overview 49 | 50 | The AI Authentication Toolkit enables privacy-preserving authentication through a cryptographic protocol that separates user identity from their authenticated sessions. This is achieved through: 51 | 52 | 1. **Token Blinding**: Clients blind tokens before sending to servers 53 | 2. **Blind Signing**: Servers sign blinded tokens without seeing the original 54 | 3. **Token Unblinding**: Clients unblind signed tokens and verify signatures 55 | 4. **Anonymous Redemption**: Clients redeem tokens without revealing identity 56 | 57 | ### Use Cases 58 | 59 | - **Privacy-Preserving Analytics**: Authenticate users for analytics without tracking 60 | - **Anonymous Voting Systems**: Verify voter eligibility without compromising ballot secrecy 61 | - **Secure Credential Systems**: Issue credentials that can't be traced back to individuals 62 | - **Rate Limiting**: Enforce usage limits without user tracking 63 | - **Abuse Prevention**: Detect fraud while preserving user privacy 64 | - **Decentralized Identity**: Implement anonymous authentication for Web3 applications 65 | 66 | ## 🏗️ Architecture 67 | 68 | ``` 69 | AI-auth-toolkit/ 70 | ├── src/ 71 | │ ├── crypto/ # Core cryptographic library (C) 72 | │ │ ├── curve/ # Elliptic curve implementations 73 | │ │ │ ├── curve.h # Abstract curve interface 74 | │ │ │ ├── curve_ed25519.* # Ed25519 curve 75 | │ │ │ └── curve_ristretto.* # Ristretto255 curve 76 | │ │ ├── voprf/ # VOPRF implementations 77 | │ │ │ ├── voprf.h # VOPRF interface 78 | │ │ │ ├── voprf_twohashdh.* # Two-hash DH base 79 | │ │ │ ├── voprf_mul_twohashdh.* # Multiplicative blinding 80 | │ │ │ └── voprf_exp_twohashdh.* # Exponential blinding 81 | │ │ ├── kdf/ # Key derivation functions 82 | │ │ │ ├── kdf.h # KDF interface 83 | │ │ │ ├── kdf_sdhi.* # SDHI KDF 84 | │ │ │ ├── kdf_naor_reingold.* # Naor-Reingold PRF 85 | │ │ │ └── kdf_default.* # Default KDF 86 | │ │ └── dleqproof/ # Discrete log equality proofs 87 | │ │ ├── dleqproof.h 88 | │ │ └── dleqproof.c 89 | │ └── service/ # Demo service implementation (C++) 90 | │ ├── SimpleAnonCredClient.* # Client implementation 91 | │ ├── SimpleAnonCredServiceHandler.* # Server handler 92 | │ ├── SimpleAnonCredServer.cpp # Server main 93 | │ ├── SimpleAnonCredClientDemo.cpp # Client demo 94 | │ └── SimpleAnonCredUtils.* # Utility functions 95 | ├── tests/ # Unit tests 96 | │ ├── dleqproof_test.cpp 97 | │ ├── kdf_test.cpp 98 | │ └── voprf_test.cpp 99 | ├── docs/ # Documentation 100 | ├── examples/ # Example implementations 101 | ├── service.thrift # Thrift API definition 102 | ├── Makefile # Build configuration 103 | └── Dockerfile # Container setup 104 | ``` 105 | 106 | ### Component Overview 107 | 108 | #### Cryptographic Core (`src/crypto/`) 109 | 110 | The cryptographic core is implemented in portable C and depends only on libsodium: 111 | 112 | - **Curves**: Abstract interface supporting multiple elliptic curves 113 | - Ed25519: High-performance, widely adopted 114 | - Ristretto255: Prime-order group for advanced protocols 115 | - **VOPRF**: Verifiable Oblivious PRF implementations 116 | - Two-Hash Diffie-Hellman construction 117 | - Both multiplicative and exponential blinding modes 118 | - Built-in DLEQ proofs for verifiability 119 | - **KDF**: Key derivation for attribute-based keys 120 | - SDHI: Secure deterministic hierarchical instantiation 121 | - Naor-Reingold: Pseudorandom function family 122 | - Default: Standard KDF for general use 123 | - **DLEQ Proofs**: Zero-knowledge proofs of discrete log equality 124 | - Schnorr-based construction 125 | - Fiat-Shamir transformation for non-interactivity 126 | 127 | #### Service Layer (`src/service/`) 128 | 129 | Reference implementation of an Anonymous Credential Service using Apache Thrift: 130 | 131 | - **Server**: Multi-threaded service handler 132 | - **Client**: Full-featured client library 133 | - **Utils**: Encoding, serialization, and helper functions 134 | 135 | ## 🚀 Quick Start 136 | 137 | ### Using Docker (Recommended) 138 | 139 | The fastest way to try out the toolkit: 140 | 141 | ```bash 142 | # Build the Docker image 143 | docker build -t ai-auth-toolkit . --build-arg UBUNTU_VERSION=22.04 144 | 145 | # Run the server 146 | docker run --rm --init --name acs-server ai-auth-toolkit 147 | 148 | # In another terminal, run the client 149 | docker exec acs-server client 150 | ``` 151 | 152 | ### Local Build 153 | 154 | If you have dependencies installed: 155 | 156 | ```bash 157 | # Clone the repository 158 | git clone https://github.com/elaineyu1031/AI-auth-toolkit.git 159 | cd AI-auth-toolkit 160 | 161 | # Build everything 162 | make 163 | 164 | # Run the server 165 | ./server 166 | 167 | # In another terminal, run the client 168 | ./client 169 | ``` 170 | 171 | ## 📦 Installation 172 | 173 | ### Prerequisites 174 | 175 | #### Required Dependencies 176 | 177 | - **C/C++ Compiler**: GCC 7+ or Clang 5+ 178 | - **libsodium**: Modern, easy-to-use crypto library 179 | 180 | ```bash 181 | # Ubuntu/Debian 182 | sudo apt-get install libsodium-dev 183 | 184 | # macOS 185 | brew install libsodium 186 | 187 | # From source 188 | git clone https://github.com/jedisct1/libsodium.git 189 | cd libsodium 190 | ./configure && make && sudo make install 191 | ``` 192 | 193 | #### For Demo Service 194 | 195 | - **Apache Thrift 0.16+**: RPC framework 196 | 197 | ```bash 198 | # Ubuntu/Debian 199 | sudo apt-get install thrift-compiler libthrift-dev 200 | 201 | # macOS 202 | brew install thrift 203 | 204 | # From source 205 | # See https://thrift.apache.org/docs/install/ 206 | ``` 207 | 208 | ### Building 209 | 210 | ```bash 211 | # Build server and client 212 | make 213 | 214 | # Build tests only 215 | make tests 216 | 217 | # Clean build artifacts 218 | make clean 219 | ``` 220 | 221 | ### Build Targets 222 | 223 | - `make` or `make all`: Build server and client 224 | - `make tests`: Build all unit tests 225 | - `make server`: Build server only 226 | - `make client`: Build client only 227 | - `make clean`: Remove all build artifacts 228 | 229 | ## 💡 Usage Examples 230 | 231 | ### Basic Client-Server Flow 232 | 233 | ```cpp 234 | #include "src/service/SimpleAnonCredClient.h" 235 | #include "src/service/SimpleAnonCredServiceHandler.h" 236 | 237 | // 1. Initialize client 238 | auto transport = std::make_shared("localhost", 9090); 239 | auto protocol = std::make_shared(transport); 240 | SimpleAnonCredClient client(protocol); 241 | transport->open(); 242 | 243 | // 2. Get primary public key (optional, for key validation) 244 | client.getPrimaryPublicKey(); 245 | 246 | // 3. Get attribute-specific public key 247 | std::vector attributes = {"app_name", "2024-01"}; 248 | client.getPublicKey(attributes); 249 | 250 | // 4. Request credential signing 251 | std::string token = generateRandomToken(); 252 | client.getCredential(token, attributes); 253 | 254 | // 5. Redeem the credential 255 | client.redeemCredential(token, attributes); 256 | ``` 257 | 258 | ### Using the Crypto Library Directly 259 | 260 | ```c 261 | #include "src/crypto/curve/curve_ristretto.h" 262 | #include "src/crypto/voprf/voprf_mul_twohashdh.h" 263 | 264 | // Initialize curve and VOPRF 265 | curve_t curve; 266 | curve_ristretto_init(&curve); 267 | voprf_t voprf; 268 | voprf_mul_twohashdh_init(&voprf, &curve); 269 | 270 | // Server: Generate key pair 271 | unsigned char sk[32], pk[32]; 272 | voprf.setup(&voprf, sk, sizeof(sk), pk, sizeof(pk)); 273 | 274 | // Client: Blind a token 275 | unsigned char token[32]; 276 | randombytes_buf(token, sizeof(token)); 277 | 278 | unsigned char blinded_element[32]; 279 | unsigned char blinding_factor[32]; 280 | voprf.blind(&voprf, 281 | blinded_element, sizeof(blinded_element), 282 | blinding_factor, sizeof(blinding_factor), 283 | token, sizeof(token)); 284 | 285 | // Server: Evaluate blinded element 286 | unsigned char evaluated_element[32]; 287 | unsigned char proof_c[32], proof_s[32]; 288 | voprf.evaluate(&voprf, 289 | evaluated_element, sizeof(evaluated_element), 290 | proof_c, sizeof(proof_c), 291 | proof_s, sizeof(proof_s), 292 | sk, sizeof(sk), 293 | blinded_element, sizeof(blinded_element), 294 | 1); // Generate proof 295 | 296 | // Client: Unblind and verify 297 | unsigned char unblinded_element[32]; 298 | voprf.verifiable_unblind(&voprf, 299 | unblinded_element, sizeof(unblinded_element), 300 | proof_c, sizeof(proof_c), 301 | proof_s, sizeof(proof_s), 302 | blinding_factor, sizeof(blinding_factor), 303 | evaluated_element, sizeof(evaluated_element), 304 | blinded_element, sizeof(blinded_element), 305 | pk, sizeof(pk), 306 | 1); // Verify proof 307 | 308 | // Finalize to get shared secret 309 | unsigned char shared_secret[64]; 310 | voprf.client_finalize(&voprf, 311 | shared_secret, sizeof(shared_secret), 312 | token, sizeof(token), 313 | unblinded_element, sizeof(unblinded_element)); 314 | ``` 315 | 316 | ### Key Derivation Example 317 | 318 | ```c 319 | #include "src/crypto/kdf/kdf_sdhi.h" 320 | 321 | // Initialize KDF 322 | curve_t curve; 323 | curve_ristretto_init(&curve); 324 | kdf_t kdf; 325 | kdf_sdhi_init(&kdf, &curve); 326 | 327 | // Setup with master secret 328 | unsigned char master_secret[32]; 329 | randombytes_buf(master_secret, sizeof(master_secret)); 330 | kdf.setup(&kdf, master_secret, sizeof(master_secret)); 331 | 332 | // Derive key from attributes 333 | const char* attrs[] = {"user_type:premium", "region:us-west"}; 334 | unsigned char derived_sk[32], derived_pk[32], pk_proof[64]; 335 | 336 | kdf.derive_key_pair(&kdf, 337 | derived_sk, sizeof(derived_sk), 338 | derived_pk, sizeof(derived_pk), 339 | pk_proof, sizeof(pk_proof), 340 | (const unsigned char**)attrs, 2); 341 | ``` 342 | 343 | ## 📖 API Reference 344 | 345 | For detailed API documentation, see [docs/API.md](docs/API.md). 346 | 347 | ### Core VOPRF Functions 348 | 349 | | Function | Description | 350 | | ---------------------- | ------------------------------- | 351 | | `setup()` | Generate server key pair | 352 | | `blind()` | Client blinds a token | 353 | | `evaluate()` | Server signs blinded token | 354 | | `verifiable_unblind()` | Client unblinds and verifies | 355 | | `client_finalize()` | Generate shared secret (client) | 356 | | `server_finalize()` | Generate shared secret (server) | 357 | 358 | ### Service API (Thrift) 359 | 360 | | Method | Description | 361 | | ------------------------ | ----------------------------------------- | 362 | | `getPrimaryPublicKey()` | Retrieve server's primary public key | 363 | | `getPublicKeyAndProof()` | Get attribute-specific public key + proof | 364 | | `signCredential()` | Sign a blinded credential | 365 | | `redeemCredential()` | Redeem and validate a credential | 366 | 367 | ## 🔄 Protocol Flow 368 | 369 | ### Complete Authentication Cycle 370 | 371 | ```mermaid 372 | sequenceDiagram 373 | participant C as Client 374 | participant S as Server 375 | 376 | Note over C,S: Setup Phase 377 | C->>S: getPrimaryPublicKey() 378 | S-->>C: primary_pk 379 | 380 | C->>S: getPublicKeyAndProof(attributes) 381 | S-->>C: pk, pk_proof 382 | C->>C: Verify pk_proof using primary_pk 383 | 384 | Note over C,S: Credential Issuance 385 | C->>C: Generate token 386 | C->>C: Blind token → blinded_token 387 | 388 | C->>S: signCredential(blinded_token, attributes) 389 | S->>S: Authenticate client 390 | S->>S: Sign blinded_token 391 | S-->>C: evaluated_token, proof 392 | 393 | C->>C: Unblind + verify proof 394 | C->>C: Generate shared_secret 395 | 396 | Note over C,S: Credential Redemption 397 | C->>S: redeemCredential(token, shared_secret, attributes) 398 | S->>S: Recompute shared_secret 399 | S->>S: Verify match 400 | S-->>C: Success / Failure 401 | ``` 402 | 403 | ### Detailed Steps 404 | 405 | 1. **Setup** (Optional but Recommended) 406 | 407 | - Client retrieves and stores server's primary public key 408 | - Used to verify all subsequently retrieved public keys 409 | - Prevents key substitution attacks 410 | 411 | 2. **Key Retrieval** 412 | 413 | - Client requests public key for specific attributes (e.g., "app_id", "date") 414 | - Server derives key pair from attributes using KDF 415 | - Server returns public key + DLEQ proof 416 | - Client verifies proof against primary key 417 | 418 | 3. **Token Issuance** 419 | 420 | - Client generates random token 421 | - Client blinds token using VOPRF 422 | - Client sends blinded token to server 423 | - Server authenticates client (separate mechanism) 424 | - Server signs blinded token 425 | - Server returns signed token + proof 426 | - Client unblinds and verifies signature 427 | 428 | 4. **Token Redemption** 429 | - Client finalizes token to get shared secret 430 | - Client sends original token + shared secret to server 431 | - Server recomputes shared secret from token 432 | - Server verifies secrets match 433 | - Server proceeds with business logic 434 | 435 | ## 🔒 Security Considerations 436 | 437 | ### Cryptographic Guarantees 438 | 439 | - **Unlinkability**: Server cannot link issuance and redemption 440 | - **Unforgeability**: Only server can produce valid signatures 441 | - **Blindness**: Server learns nothing about the token 442 | - **Verifiability**: Client can verify server's signatures 443 | - **One-More Forgery Resistance**: Client cannot produce extra valid tokens 444 | 445 | ### Implementation Security 446 | 447 | - Uses libsodium for constant-time operations 448 | - Secure random number generation via `randombytes_buf()` 449 | - No secret-dependent branching or memory access 450 | - Proper zeroing of sensitive memory 451 | 452 | ### Best Practices 453 | 454 | 1. **Key Management** 455 | 456 | - Rotate master keys regularly 457 | - Use attribute-based key derivation 458 | - Store keys in secure key management systems (HSM/KMS) 459 | 460 | 2. **Token Generation** 461 | 462 | - Always use cryptographically secure random tokens 463 | - Minimum 128 bits of entropy 464 | - Never reuse tokens 465 | 466 | 3. **Transport Security** 467 | 468 | - Always use TLS for client-server communication 469 | - Implement mutual authentication 470 | - Use certificate pinning where possible 471 | 472 | 4. **Rate Limiting** 473 | 474 | - Limit credential issuance per client 475 | - Implement exponential backoff 476 | - Monitor for abuse patterns 477 | 478 | 5. **Attribute Design** 479 | - Include time-based attributes (e.g., date, hour) 480 | - Use specific, narrow scopes 481 | - Implement attribute expiry 482 | 483 | ### Known Limitations 484 | 485 | - Server must maintain state for double-spend prevention 486 | - Requires separate client authentication mechanism 487 | - Not quantum-resistant (uses elliptic curves) 488 | 489 | ## ⚡ Performance 490 | 491 | ### Benchmarks 492 | 493 | Measured on: Intel Core i7-9750H @ 2.60GHz, Ubuntu 22.04 494 | 495 | | Operation | Time (µs) | Throughput (ops/sec) | 496 | | ---------------- | --------- | -------------------- | 497 | | Key Generation | ~50 | 20,000 | 498 | | Token Blinding | ~80 | 12,500 | 499 | | Token Evaluation | ~90 | 11,100 | 500 | | Token Unblinding | ~110 | 9,090 | 501 | | Finalization | ~45 | 22,200 | 502 | | **Full Cycle** | **~375** | **~2,600** | 503 | 504 | ### Optimization Tips 505 | 506 | 1. **Batch Operations**: Process multiple tokens in parallel 507 | 2. **Key Caching**: Cache derived keys for common attributes 508 | 3. **Connection Pooling**: Reuse Thrift connections 509 | 4. **Async I/O**: Use non-blocking I/O for network operations 510 | 5. **Curve Selection**: Ristretto255 offers better performance 511 | 512 | ## 🧪 Testing 513 | 514 | ```bash 515 | # Build tests 516 | make tests 517 | 518 | # Run all tests 519 | ./tests/dleqproof_test 520 | ./tests/kdf_test 521 | ./tests/voprf_test 522 | 523 | # Run with verbose output 524 | ./tests/voprf_test --verbose 525 | ``` 526 | 527 | ### Test Coverage 528 | 529 | - **Unit Tests**: Individual component testing 530 | - **Integration Tests**: Full protocol flow testing 531 | - **Security Tests**: Verification of cryptographic properties 532 | - **Performance Tests**: Benchmarking critical paths 533 | 534 | ## 🤝 Contributing 535 | 536 | We welcome contributions! Please see [CONTRIBUTING.md](CONTRIBUTING.md) for guidelines. 537 | 538 | ### Development Setup 539 | 540 | ```bash 541 | # Clone the repository 542 | git clone https://github.com/elaineyu1031/AI-auth-toolkit.git 543 | cd AI-auth-toolkit 544 | 545 | # Create a development branch 546 | git checkout -b feature/your-feature-name 547 | 548 | # Make changes and test 549 | make clean && make && make tests 550 | 551 | # Run all tests 552 | ./tests/dleqproof_test && ./tests/kdf_test && ./tests/voprf_test 553 | 554 | # Submit a pull request 555 | ``` 556 | 557 | ### Code Style 558 | 559 | - C code: Follow kernel style guidelines 560 | - C++ code: Follow Google C++ style guide 561 | - Document all public APIs 562 | - Include unit tests for new features 563 | 564 | ## 📄 License 565 | 566 | This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details. 567 | 568 | ## 🙏 Acknowledgments 569 | 570 | - Built on [libsodium](https://libsodium.org/) - Modern cryptographic library 571 | - Uses [Apache Thrift](https://thrift.apache.org/) for RPC framework 572 | - Implements cryptographic protocols based on academic research and IETF standards 573 | - Community contributors and open-source cryptography research 574 | 575 | ## 📚 Further Reading 576 | 577 | - [VOPRF IETF RFC Draft](https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-voprf) - Official VOPRF specification 578 | - [Privacy Pass Protocol](https://privacypass.github.io/) - Related anonymous credential protocol 579 | - [Ristretto Group](https://ristretto.group/) - Prime-order elliptic curve group 580 | - [libsodium Documentation](https://doc.libsodium.org/) - Cryptographic primitives 581 | - [Anonymous Credentials: A Survey](https://eprint.iacr.org/2013/516.pdf) - Academic overview 582 | 583 | ## 📧 Contact & Support 584 | 585 | - **Issues**: [GitHub Issues](https://github.com/elaineyu1031/AI-auth-toolkit/issues) 586 | - **Discussions**: [GitHub Discussions](https://github.com/elaineyu1031/AI-auth-toolkit/discussions) 587 | - **Security**: Report security vulnerabilities privately to the maintainers 588 | - **Maintainer**: [@elaineyu1031](https://github.com/elaineyu1031) 589 | 590 | ## ⚖️ Legal 591 | 592 | The project implements standard cryptographic protocols based on public research and IETF specifications. Some reference implementations were consulted during development, and appropriate attribution is maintained in source files as required by their respective licenses. 593 | 594 | --- 595 | 596 | **Built with ❤️ for privacy-preserving authentication by the open-source community** 597 | --------------------------------------------------------------------------------