├── .chglog ├── CHANGELOG.tpl.md └── config.yml ├── .github ├── FUNDING.yml └── workflows │ ├── changelog.yml │ ├── erlang.yml │ └── git.yml ├── .gitignore ├── CHANGELOG.md ├── LICENSE ├── PROTOCOL.sshsig.txt ├── README.md ├── rebar.config ├── rebar.lock ├── src ├── ssh_signature.app.src └── ssh_signature.erl └── test └── ssh_signature_SUITE.erl /.chglog/CHANGELOG.tpl.md: -------------------------------------------------------------------------------- 1 | {{ if .Versions -}} 2 | 3 | ## [Unreleased] 4 | 5 | {{ if .Unreleased.CommitGroups -}} 6 | {{ range .Unreleased.CommitGroups -}} 7 | ### {{ .Title }} 8 | {{ range .Commits -}} 9 | - {{ if .Scope }}**{{ .Scope }}:** {{ end }}{{ .Subject }} 10 | {{ end }} 11 | {{ end -}} 12 | {{ end -}} 13 | {{ end -}} 14 | 15 | {{ range .Versions }} 16 | 17 | ## {{ if .Tag.Previous }}[{{ .Tag.Name }}]{{ else }}{{ .Tag.Name }}{{ end }} - {{ datetime "2006-01-02" .Tag.Date }} 18 | {{ range .CommitGroups -}} 19 | ### {{ .Title }} 20 | {{ range .Commits -}} 21 | - {{ if .Scope }}**{{ .Scope }}:** {{ end }}{{ .Subject }} ([`{{ .Hash.Short }}`]({{ $.Info.RepositoryURL }}/commit/{{ .Hash.Long }})) 22 | {{ end }} 23 | {{ end -}} 24 | 25 | {{- if .NoteGroups -}} 26 | {{ range .NoteGroups -}} 27 | ### {{ .Title }} 28 | {{ range .Notes }} 29 | {{ .Body }} 30 | {{ end }} 31 | {{ end -}} 32 | {{ end -}} 33 | {{ end -}} 34 | 35 | {{- if .Versions }} 36 | [Unreleased]: {{ .Info.RepositoryURL }}/compare/{{ $latest := index .Versions 0 }}{{ $latest.Tag.Name }}...HEAD 37 | {{ range .Versions -}} 38 | {{ if .Tag.Previous -}} 39 | [{{ .Tag.Name }}]: {{ $.Info.RepositoryURL }}/compare/{{ .Tag.Previous.Name }}...{{ .Tag.Name }} 40 | {{ end -}} 41 | {{ end -}} 42 | {{ end -}} 43 | -------------------------------------------------------------------------------- /.chglog/config.yml: -------------------------------------------------------------------------------- 1 | style: github 2 | template: CHANGELOG.tpl.md 3 | info: 4 | title: CHANGELOG 5 | repository_url: https://github.com/hauleth/ssh_signature 6 | options: 7 | commits: 8 | filters: 9 | Type: 10 | - ft 11 | - fix 12 | - docs 13 | commit_groups: 14 | title_maps: 15 | ft: Features 16 | fix: Bug Fixes 17 | docs: Documentation 18 | header: 19 | pattern: "^(\\w*)(?:\\(([\\w\\$\\.\\-\\*\\s]*)\\))?!?\\:\\s(.*)$" 20 | pattern_maps: 21 | - Type 22 | - Scope 23 | - Subject 24 | notes: 25 | keywords: 26 | - BREAKING CHANGE 27 | -------------------------------------------------------------------------------- /.github/FUNDING.yml: -------------------------------------------------------------------------------- 1 | # These are supported funding model platforms 2 | 3 | github: [hauleth] 4 | -------------------------------------------------------------------------------- /.github/workflows/changelog.yml: -------------------------------------------------------------------------------- 1 | name: Changelog 2 | 3 | on: 4 | push: 5 | branches: [ master ] 6 | 7 | jobs: 8 | update-changelog: 9 | name: Update changelog 10 | runs-on: ubuntu-latest 11 | steps: 12 | - uses: actions/checkout@v2 13 | with: 14 | fetch-depth: 0 15 | ref: master 16 | - uses: Bpazy/setup-git-chglog@v1 17 | - name: git-chglog version 18 | run: git chglog --version 19 | - name: Generate changelog 20 | run: git chglog | tee CHANGELOG.md 21 | - name: Commit 22 | run: | 23 | git config user.email "" 24 | git config user.name "GitHub Action Bot" 25 | git diff -- CHANGELOG.md 26 | git commit -m "chore: update CHANGELOG [skip ci]" CHANGELOG.md && git push origin master || true 27 | -------------------------------------------------------------------------------- /.github/workflows/erlang.yml: -------------------------------------------------------------------------------- 1 | name: Erlang CI 2 | 3 | on: [push, pull_request] 4 | 5 | jobs: 6 | build: 7 | runs-on: ubuntu-latest 8 | strategy: 9 | fail-fast: false 10 | matrix: 11 | otp_version: ['22', '23', '24', '25'] 12 | steps: 13 | - name: Install OpenSSH 14 | run: sudo apt install openssh-client 15 | - uses: actions/checkout@v1 16 | - name: Set up Erlang 17 | uses: erlef/setup-beam@v1 18 | with: 19 | otp-version: ${{ matrix.otp_version }} 20 | rebar3-version: '3.16' 21 | - name: Compile 22 | run: rebar3 compile 23 | - name: Run tests 24 | run: rebar3 do ct --cover 25 | env: 26 | SHELL: /bin/sh 27 | - name: Check Dialyzer results 28 | run: rebar3 dialyzer 29 | - name: Generate coverage data 30 | run: rebar3 covertool generate 31 | - uses: codecov/codecov-action@v1 32 | with: 33 | file: ./_build/test/covertool/ssh_signature.covertool.xml 34 | flags: otp-${{ matrix.otp_version }} 35 | 36 | docs: 37 | runs-on: ubuntu-latest 38 | steps: 39 | - uses: actions/checkout@v1 40 | - name: Set up Erlang 41 | uses: erlef/setup-beam@v1 42 | with: 43 | otp-version: '25' 44 | rebar3-version: '3.16' 45 | - name: Check if docs build 46 | run: rebar3 ex_doc 47 | -------------------------------------------------------------------------------- /.github/workflows/git.yml: -------------------------------------------------------------------------------- 1 | name: Git 2 | 3 | on: 4 | pull_request_target: 5 | branches: [ master ] 6 | 7 | jobs: 8 | commit-messages: 9 | name: Check commit messages 10 | runs-on: ubuntu-latest 11 | steps: 12 | - uses: actions/checkout@v2 13 | with: 14 | fetch-depth: 0 15 | ref: ${{ github.event.pull_request.head.sha }} 16 | - name: Get PR URL 17 | uses: Dovyski/payload-info-action@master 18 | id: issue_url 19 | with: 20 | filter_pull_request: '.pull_request._links.issue.href' 21 | - name: Check 22 | env: 23 | TYPES: ft|fix|docs|chore|test 24 | run: | 25 | ! git log --oneline -E --invert-grep --grep="^($TYPES)(\([^)]\))?:" --pretty=format:"::error title=Invalid commit message::%h %s" origin/$GITHUB_BASE_REF... | grep "." 26 | - name: Unlabel correct PR 27 | if: ${{ success() }} 28 | run: | 29 | curl -X DELETE \ 30 | --header 'authorization: Bearer ${{ github.token }}' \ 31 | --header 'content-type: application/json' \ 32 | ${{ steps.issue_url.outputs.value }}/labels/invalid/commit-messages 33 | - name: Label PR with invalid commit messages 34 | if: ${{ failure() }} 35 | run: | 36 | curl -X POST \ 37 | --header 'authorization: Bearer ${{ github.token }}' \ 38 | --header 'content-type: application/json' \ 39 | --data '["invalid/commit-messages"]' \ 40 | ${{ steps.issue_url.outputs.value }}/labels 41 | 42 | # labeler: 43 | # name: Label PRs depending on changes 44 | # runs-on: ubuntu-latest 45 | # steps: 46 | # - uses: actions/checkout@v2 47 | # with: 48 | # fetch-depth: 0 49 | # ref: ${{ github.event.pull_request.head.sha }} 50 | # - uses: actions/labeler@v3 51 | # with: 52 | # repo-token: "${{ github.token }}" 53 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | .rebar3 2 | _* 3 | .eunit 4 | *.o 5 | *.beam 6 | *.plt 7 | *.swp 8 | *.swo 9 | .erlang.cookie 10 | ebin 11 | log 12 | erl_crash.dump 13 | .rebar 14 | logs 15 | _build 16 | .idea 17 | *.iml 18 | rebar3.crashdump 19 | *~ 20 | /doc 21 | -------------------------------------------------------------------------------- /CHANGELOG.md: -------------------------------------------------------------------------------- 1 | 2 | ## [Unreleased] 3 | 4 | 5 | 6 | ## v0.1.0 - 2022-08-20 7 | ### Bug Fixes 8 | - conditionaly use removed function ([`784871a`](https://github.com/hauleth/ssh_signature/commit/784871a584db40a6a2e954b5d6093babecf0a28e)) 9 | - install OpenSSL GitHub Actions ([`09dd972`](https://github.com/hauleth/ssh_signature/commit/09dd9727b849c5cb90f411041f377a80839a0d40)) 10 | 11 | ### Documentation 12 | - add protocol description to the docs ([`efd03d2`](https://github.com/hauleth/ssh_signature/commit/efd03d279772c9ff159748cedb33c9c780e30ba5)) 13 | - add example in README ([`b694f60`](https://github.com/hauleth/ssh_signature/commit/b694f6004b7e64a0ded835a59098e5e9e8b3c04b)) 14 | 15 | 16 | [Unreleased]: https://github.com/hauleth/ssh_signature/compare/v0.1.0...HEAD 17 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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While redistributing 166 | the Work or Derivative Works thereof, You may choose to offer, 167 | and charge a fee for, acceptance of support, warranty, indemnity, 168 | or other liability obligations and/or rights consistent with this 169 | License. However, in accepting such obligations, You may act only 170 | on Your own behalf and on Your sole responsibility, not on behalf 171 | of any other Contributor, and only if You agree to indemnify, 172 | defend, and hold each Contributor harmless for any liability 173 | incurred by, or claims asserted against, such Contributor by reason 174 | of your accepting any such warranty or additional liability. 175 | 176 | END OF TERMS AND CONDITIONS 177 | 178 | Copyright 2022, Łukasz Niemier . 179 | 180 | Licensed under the Apache License, Version 2.0 (the "License"); 181 | you may not use this file except in compliance with the License. 182 | You may obtain a copy of the License at 183 | 184 | http://www.apache.org/licenses/LICENSE-2.0 185 | 186 | Unless required by applicable law or agreed to in writing, software 187 | distributed under the License is distributed on an "AS IS" BASIS, 188 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 189 | See the License for the specific language governing permissions and 190 | limitations under the License. 191 | 192 | -------------------------------------------------------------------------------- /PROTOCOL.sshsig.txt: -------------------------------------------------------------------------------- 1 | This document describes a lightweight SSH Signature format 2 | that is compatible with SSH keys and wire formats. 3 | 4 | At present, only detached and armored signatures are supported. 5 | 6 | 1. Armored format 7 | 8 | The Armored SSH signatures consist of a header, a base64 9 | encoded blob, and a footer. 10 | 11 | The header is the string "-----BEGIN SSH SIGNATURE-----" 12 | followed by a newline. The footer is the string 13 | "-----END SSH SIGNATURE-----" immediately after a newline. 14 | 15 | The header MUST be present at the start of every signature. 16 | Files containing the signature MUST start with the header. 17 | Likewise, the footer MUST be present at the end of every 18 | signature. 19 | 20 | The base64 encoded blob SHOULD be broken up by newlines 21 | every 76 characters. 22 | 23 | Example: 24 | 25 | -----BEGIN SSH SIGNATURE----- 26 | U1NIU0lHAAAAAQAAADMAAAALc3NoLWVkMjU1MTkAAAAgJKxoLBJBivUPNTUJUSslQTt2hD 27 | jozKvHarKeN8uYFqgAAAADZm9vAAAAAAAAAFMAAAALc3NoLWVkMjU1MTkAAABAKNC4IEbt 28 | Tq0Fb56xhtuE1/lK9H9RZJfON4o6hE9R4ZGFX98gy0+fFJ/1d2/RxnZky0Y7GojwrZkrHT 29 | FgCqVWAQ== 30 | -----END SSH SIGNATURE----- 31 | 32 | 2. Blob format 33 | 34 | #define MAGIC_PREAMBLE "SSHSIG" 35 | #define SIG_VERSION 0x01 36 | 37 | byte[6] MAGIC_PREAMBLE 38 | uint32 SIG_VERSION 39 | string publickey 40 | string namespace 41 | string reserved 42 | string hash_algorithm 43 | string signature 44 | 45 | The publickey field MUST contain the serialisation of the 46 | public key used to make the signature using the usual SSH 47 | encoding rules, i.e RFC4253, RFC5656, 48 | draft-ietf-curdle-ssh-ed25519-ed448, etc. 49 | 50 | Verifiers MUST reject signatures with versions greater than those 51 | they support. 52 | 53 | The purpose of the namespace value is to specify a unambiguous 54 | interpretation domain for the signature, e.g. file signing. 55 | This prevents cross-protocol attacks caused by signatures 56 | intended for one intended domain being accepted in another. 57 | The namespace value MUST NOT be the empty string. 58 | 59 | The reserved value is present to encode future information 60 | (e.g. tags) into the signature. Implementations should ignore 61 | the reserved field if it is not empty. 62 | 63 | Data to be signed is first hashed with the specified hash_algorithm. 64 | This is done to limit the amount of data presented to the signature 65 | operation, which may be of concern if the signing key is held in limited 66 | or slow hardware or on a remote ssh-agent. The supported hash algorithms 67 | are "sha256" and "sha512". 68 | 69 | The signature itself is made using the SSH signature algorithm and 70 | encoding rules for the chosen key type. For RSA signatures, the 71 | signature algorithm must be "rsa-sha2-512" or "rsa-sha2-256" (i.e. 72 | not the legacy RSA-SHA1 "ssh-rsa"). 73 | 74 | This blob is encoded as a string using the RFC4253 encoding 75 | rules and base64 encoded to form the middle part of the 76 | armored signature. 77 | 78 | 79 | 3. Signed Data, of which the signature goes into the blob above 80 | 81 | #define MAGIC_PREAMBLE "SSHSIG" 82 | 83 | byte[6] MAGIC_PREAMBLE 84 | string namespace 85 | string reserved 86 | string hash_algorithm 87 | string H(message) 88 | 89 | The preamble is the six-byte sequence "SSHSIG". It is included to 90 | ensure that manual signatures can never be confused with any message 91 | signed during SSH user or host authentication. 92 | 93 | The reserved value is present to encode future information 94 | (e.g. tags) into the signature. Implementations should ignore 95 | the reserved field if it is not empty. 96 | 97 | The data is concatenated and passed to the SSH signing 98 | function. 99 | 100 | $OpenBSD: PROTOCOL.sshsig,v 1.4 2020/08/31 00:17:41 djm Exp $ 101 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | SSH signatures for Erlang 2 | ===== 3 | 4 | Implementation of [SSH signatures][ssh-keygen-sign] in Erlang. It uses only 5 | stuff distributed with OTP, so no external dependencies needed. 6 | 7 | [ssh-keygen-sign]: https://man.openbsd.org/ssh-keygen#Y~4 8 | 9 | Currently supported algorithms: 10 | 11 | - RSA 12 | - Ed25519 13 | - Ed448 - not tested, as my implementation of OpenSSH do not support Ed448 keys 14 | 15 | ## Usage 16 | 17 | There are just 3 exported functions: 18 | 19 | - `sign/{3,4}` which allows signing data 20 | - `verify/2` that verifies the signature for given data and outputs details 21 | about signature 22 | 23 | ```erlang 24 | % First we need the private key that we will use for signing. 25 | % For the purpose of this example just use RSA-4096 26 | SecretKey = public_key:generate_key({rsa, 4096, 3}), 27 | 28 | Data = <<"Foo">>, 29 | 30 | % Sign data using our key. 3rd argument there is a namespace, that must be 31 | % non-empty string. 32 | Signature = ssh_signature:sign(Data, SecretKey, "text"), 33 | 34 | % The created signature is already in armoured (ASCII-only) format. 35 | 36 | % Now we can check if the signature is correct 37 | {ok, #{public_key := PubKey, ns := <<"test">>, signature := Sig}} = 38 | ssh_signature:verify(Data, Signature). 39 | % Notice that we do not pass public key to verify/2, it is left to the user to 40 | % check whether the returned public key is trusted. 41 | ``` 42 | 43 | ## License 44 | 45 | See [LICENSE](LICENSE) 46 | -------------------------------------------------------------------------------- /rebar.config: -------------------------------------------------------------------------------- 1 | {erl_opts, [ 2 | debug_info, 3 | warnings_as_errors 4 | ]}. 5 | 6 | {project_plugins, [ 7 | rebar3_ex_doc, 8 | rebar3_lint, 9 | covertool, 10 | erlfmt 11 | ]}. 12 | 13 | {deps, []}. 14 | 15 | {ct_opts, [{create_priv_dir, manual_per_tc}]}. 16 | 17 | {profiles, [ 18 | {test, [ 19 | {deps, [erlexec]}, 20 | {erl_opts, [nowarn_export_all]} 21 | ]} 22 | ]}. 23 | 24 | {ex_doc, [ 25 | {extras, [ 26 | <<"README.md">>, 27 | <<"LICENSE">>, 28 | <<"CHANGELOG.md">>, 29 | <<"PROTOCOL.sshsig.txt">> 30 | ]}, 31 | {main, <<"readme">>} 32 | ]}. 33 | 34 | {hex, [ 35 | {doc, #{provider => ex_doc}} 36 | ]}. 37 | 38 | {erlfmt, [ 39 | write, 40 | {print_width, 81} 41 | ]}. 42 | 43 | {elvis, [ 44 | #{ 45 | dirs => ["apps/*/src", "src"], 46 | filter => "*.erl", 47 | rules => [ 48 | % {elvis_style, line_length, #{ 49 | % ignore => [], 50 | % limit => 81, 51 | % skip_comments => whole_line 52 | % }}, 53 | % {elvis_style, no_tabs}, 54 | % {elvis_style, no_trailing_whitespace}, 55 | {elvis_style, macro_names, #{ignore => []}}, 56 | {elvis_style, macro_module_names}, 57 | {elvis_style, operator_spaces, #{ 58 | rules => [ 59 | {right, ","}, 60 | {right, "++"}, 61 | {left, "++"} 62 | ] 63 | }}, 64 | {elvis_style, nesting_level, #{level => 3}}, 65 | {elvis_style, god_modules, #{ 66 | limit => 25, 67 | ignore => [] 68 | }}, 69 | {elvis_style, no_if_expression}, 70 | {elvis_style, invalid_dynamic_call, #{ 71 | ignore => [ 72 | systemd_journal_h, 73 | systemd_kmsg_formatter 74 | ] 75 | }}, 76 | {elvis_style, used_ignored_variable}, 77 | {elvis_style, no_behavior_info}, 78 | { 79 | elvis_style, 80 | module_naming_convention, 81 | #{ 82 | regex => "^[a-z]([a-z0-9]*_?)*(_SUITE)?$", 83 | ignore => [] 84 | } 85 | }, 86 | { 87 | elvis_style, 88 | function_naming_convention, 89 | #{regex => "^([a-z][a-z0-9]*_?)*$"} 90 | }, 91 | {elvis_style, state_record_and_type}, 92 | {elvis_style, no_spec_with_records}, 93 | {elvis_style, dont_repeat_yourself, #{min_complexity => 20}}, 94 | {elvis_style, no_debug_call, #{ignore => []}} 95 | ] 96 | }, 97 | #{ 98 | dirs => ["."], 99 | filter => "rebar.config", 100 | rules => [ 101 | {elvis_project, no_deps_master_rebar, #{ignore => []}}, 102 | {elvis_project, protocol_for_deps_rebar, #{ignore => []}} 103 | ] 104 | } 105 | ]}. 106 | -------------------------------------------------------------------------------- /rebar.lock: -------------------------------------------------------------------------------- 1 | []. 2 | -------------------------------------------------------------------------------- /src/ssh_signature.app.src: -------------------------------------------------------------------------------- 1 | {application, ssh_signature, [ 2 | {description, "Pure Erlang implementation of SSH signatures"}, 3 | {vsn, git}, 4 | {registered, []}, 5 | {applications, [ 6 | kernel, 7 | stdlib, 8 | public_key, 9 | ssh 10 | ]}, 11 | {env, []}, 12 | {modules, []}, 13 | 14 | {licenses, ["Apache 2.0"]}, 15 | {links, [ 16 | {"GitHub", "https://github.com/hauleth/ssh_signature"}, 17 | {"PROTOCOL.sshsig", 18 | "https://raw.githubusercontent.com/openssh/openssh-portable/6851f4b8c3fc1b3e1114c56106e4dc31369c8513/PROTOCOL.sshsig"} 19 | ]} 20 | ]}. 21 | -------------------------------------------------------------------------------- /src/ssh_signature.erl: -------------------------------------------------------------------------------- 1 | -module(ssh_signature). 2 | 3 | -dialyzer([ 4 | {no_improper_lists, split/1}, 5 | % Needed due to fact that OTP 25 removed `{ed_pri, _, _, _}' key format 6 | {no_match, [ 7 | ed_to_pub/1, 8 | pk_sign/3, 9 | pk_verify/4, 10 | priv_to_public/1, 11 | sig_type/2, 12 | type_sig/3 13 | ]}, 14 | {nowarn_function, [pk_sign/3, pk_verify/4]} 15 | ]). 16 | 17 | -include_lib("public_key/include/public_key.hrl"). 18 | 19 | -export([sign/3, sign/4]). 20 | -export([verify/2]). 21 | 22 | -ifdef(TEST). 23 | -export([priv_to_public/1, decode/1]). 24 | -endif. 25 | 26 | -export_type([namespace/0, hash_algorithm/0]). 27 | 28 | -define(MAGIC_PREAMBLE, "SSHSIG"). 29 | -define(SIG_VERSION, 16#01). 30 | -define(UINT32(X), (X):32 / unsigned - big - integer). 31 | -define(STRING(X), ?UINT32(size(X)), (X) / binary). 32 | -define(BEGIN, "-----BEGIN SSH SIGNATURE-----"). 33 | -define(END, "-----END SSH SIGNATURE-----"). 34 | 35 | -type namespace() :: unicode:chardata(). 36 | -type hash_algorithm() :: sha256 | sha512. 37 | 38 | %% @equiv sign(Data, Key, NS, #{}) 39 | sign(Data, Key, NS) -> sign(Data, Key, NS, #{}). 40 | 41 | %% @doc Sign `Data' using SSH signature format with `Key'. 42 | %% 43 | %% The `NS' must be not empty. 44 | %% 45 | %% == Options == 46 | %% 47 | %% 51 | %% @end 52 | -spec sign(iodata(), public_key:private_key(), namespace(), Opts) -> 53 | unicode:chardata() 54 | when 55 | Opts :: #{ 56 | hash => hash_algorithm() 57 | }. 58 | sign(Data, Key, NS, Opts) -> 59 | NS0 = iolist_to_binary(NS), 60 | case NS0 of 61 | <<>> -> error({badarg, empty_namespace}); 62 | _ -> ok 63 | end, 64 | Algo = maps:get(hash, Opts, sha512), 65 | Reserved = <<"">>, 66 | Body = body(Data, NS0, Reserved, Algo), 67 | Signature = pk_sign(Body, Algo, Key), 68 | SigType = sig_type(Key, Algo), 69 | Sig = <>, 70 | EncPub = encode(priv_to_public(Key)), 71 | Result = 72 | <>, 75 | iolist_to_binary([?BEGIN, $\n, split(base64:encode(Result)), $\n, ?END]). 76 | 77 | %% @doc Verify `Signature' of `Data'. 78 | %% 79 | %% Notice that this function do not check authenticity of the provided key. That 80 | %% is left to the user to check whether key used for signing match the 81 | %% requirements. 82 | %% 83 | %% @end 84 | -spec verify(iodata(), unicode:chardata()) -> {ok, Result} | {error, term()} when 85 | Result :: #{ 86 | ns => namespace(), 87 | public_key => public_key:public_key(), 88 | signature => binary() 89 | }. 90 | verify(Data, Signature) -> 91 | Sig0 = string:trim(Signature), 92 | Sig1 = iolist_to_binary(Sig0), 93 | Size = byte_size(Sig1) - length(?BEGIN) - length(?END) - 2, 94 | case Sig1 of 95 | <> -> 96 | Sig3 = base64:decode(Sig2), 97 | case parse(Sig3) of 98 | {ok, #{ 99 | ns := NS, 100 | pk := PublicKey, 101 | reserved := R, 102 | signature := {_, Sig}, 103 | hash_algorithm := Algo 104 | }} -> 105 | Body = body(Data, NS, R, Algo), 106 | case pk_verify(Body, Algo, Sig, PublicKey) of 107 | true -> 108 | {ok, #{ 109 | ns => NS, 110 | public_key => PublicKey, 111 | signature => Sig 112 | }}; 113 | false -> 114 | {error, invalid_signature} 115 | end; 116 | {error, _} = Error -> 117 | Error 118 | end; 119 | _ -> 120 | {error, invalid_armour} 121 | end. 122 | 123 | parse( 124 | <> 128 | ) when 129 | SigDS =:= SAS + 4 + SigS + 4, 130 | (SAlgo =:= <<"sha256">> orelse SAlgo =:= <<"sha512">>) 131 | -> 132 | PubKey = decode(EncPub), 133 | Algo = 134 | case SAlgo of 135 | <<"sha256">> -> sha256; 136 | <<"sha512">> -> sha512 137 | end, 138 | case type_sig(SigAlgo, PubKey, Algo) of 139 | true -> 140 | {ok, #{ 141 | version => Version, 142 | pk => PubKey, 143 | ns => NS, 144 | reserved => R, 145 | hash_algorithm => Algo, 146 | signature => {SigAlgo, Sig} 147 | }}; 148 | _ -> 149 | {error, type_mismatch} 150 | end; 151 | parse(_) -> 152 | {error, invalid_format}. 153 | 154 | pk_sign(Body, _, {ed_pri, _, _, _} = Key) -> 155 | public_key:sign(Body, none, Key); 156 | pk_sign(Body, _, #'ECPrivateKey'{} = Key) -> 157 | public_key:sign(Body, none, Key); 158 | pk_sign(Body, Algo, #'RSAPrivateKey'{} = Key) -> 159 | public_key:sign(Body, Algo, Key). 160 | 161 | pk_verify(Body, _, Sig, {ed_pub, _, _} = Key) -> 162 | public_key:verify(Body, none, Sig, Key); 163 | pk_verify(Body, _, Sig, {#'ECPoint'{}, _} = Key) -> 164 | public_key:verify(Body, none, Sig, Key); 165 | pk_verify(Body, Algo, Sig, #'RSAPublicKey'{} = Key) -> 166 | public_key:verify(Body, Algo, Sig, Key). 167 | 168 | body(Data, NS, R, Algo) -> 169 | H = crypto:hash(Algo, Data), 170 | <>. 172 | 173 | sig_type({ed_pri, Type, _Pub, _Pri}, _Algo) -> 174 | <<"ssh-", (atom_to_binary(Type, utf8))/binary>>; 175 | sig_type(#'ECPrivateKey'{parameters = {namedCurve, ?'id-Ed25519'}}, _) -> 176 | <<"ssh-ed25519">>; 177 | sig_type(#'ECPrivateKey'{parameters = {namedCurve, ?'id-Ed448'}}, _) -> 178 | <<"ssh-ed448">>; 179 | sig_type(#'RSAPrivateKey'{}, sha256) -> 180 | <<"rsa-sha2-256">>; 181 | sig_type(#'RSAPrivateKey'{}, sha512) -> 182 | <<"rsa-sha2-512">>. 183 | 184 | type_sig(<<"ssh-ed25519">>, {ed_pub, ed25519, _}, _) -> true; 185 | type_sig(<<"ssh-ed25519">>, {_, {namedCurve, ?'id-Ed25519'}}, _) -> true; 186 | type_sig(<<"ssh-ed448">>, {_, {namedCurve, ?'id-Ed448'}}, _) -> true; 187 | type_sig(<<"ssh-ed448">>, {ed_pub, ed448, _}, _) -> true; 188 | type_sig(<<"rsa-sha2-256">>, #'RSAPublicKey'{}, sha256) -> true; 189 | type_sig(<<"rsa-sha2-512">>, #'RSAPublicKey'{}, sha512) -> true; 190 | type_sig(_, _, _) -> false. 191 | 192 | -spec priv_to_public(public_key:private_key()) -> public_key:public_key(). 193 | priv_to_public({ed_pri, _, _, _} = Priv) -> 194 | ed_to_pub(Priv); 195 | priv_to_public(#'ECPrivateKey'{} = Priv) -> 196 | ed_to_pub(Priv); 197 | priv_to_public(#'RSAPrivateKey'{modulus = Mod, publicExponent = Exp}) -> 198 | #'RSAPublicKey'{modulus = Mod, publicExponent = Exp}; 199 | priv_to_public(Other) -> 200 | Other. 201 | 202 | -if(?OTP_RELEASE < 25). 203 | ed_to_pub({ed_pri, Type, Pub, _Priv}) -> 204 | {ed_pub, Type, Pub}; 205 | ed_to_pub(#'ECPrivateKey'{ 206 | parameters = {namedCurve, ?'id-Ed25519'}, publicKey = Pub 207 | }) -> 208 | {ed_pub, ed25519, Pub}; 209 | ed_to_pub(#'ECPrivateKey'{ 210 | parameters = {namedCurve, ?'id-Ed448'}, publicKey = Pub 211 | }) -> 212 | {ed_pub, ed448, Pub}. 213 | -else. 214 | ed_to_pub({ed_pri, Type, Pub, _Priv}) -> 215 | {#'ECPoint'{point = Pub}, Type}; 216 | ed_to_pub(#'ECPrivateKey'{parameters = Type, publicKey = Pub}) -> 217 | {#'ECPoint'{point = Pub}, Type}. 218 | -endif. 219 | 220 | -spec encode(public_key:public_key()) -> binary(). 221 | -spec decode(binary()) -> public_key:public_key(). 222 | -if(?OTP_RELEASE < 24). 223 | encode(Key) -> 224 | public_key:ssh_encode(Key, ssh2_pubkey). 225 | 226 | decode(Key) -> 227 | public_key:ssh_decode(Key, ssh2_pubkey). 228 | -else. 229 | encode(Key) -> 230 | ssh_file:encode(Key, ssh2_pubkey). 231 | 232 | decode(Key) -> 233 | ssh_file:decode(Key, ssh2_pubkey). 234 | -endif. 235 | 236 | split(<>) -> 237 | [D, $\n | split(Rest)]; 238 | split(Rest) -> 239 | Rest. 240 | -------------------------------------------------------------------------------- /test/ssh_signature_SUITE.erl: -------------------------------------------------------------------------------- 1 | -module(ssh_signature_SUITE). 2 | 3 | -include_lib("public_key/include/public_key.hrl"). 4 | 5 | % -compile(export_all). 6 | 7 | -export([ 8 | all/0, 9 | groups/0, 10 | init_per_group/2, 11 | end_per_group/2, 12 | can_verify_signed/1, 13 | signature_can_be_verified_by_openssh/1, 14 | openssh_can_be_verified/1 15 | ]). 16 | 17 | -include_lib("stdlib/include/assert.hrl"). 18 | -include_lib("common_test/include/ct.hrl"). 19 | 20 | all() -> 21 | [ 22 | {group, ed25519}, 23 | {group, rsa2048}, 24 | {group, rsa3072}, 25 | {group, rsa4096} 26 | ]. 27 | 28 | groups() -> 29 | Tests = [ 30 | can_verify_signed, 31 | signature_can_be_verified_by_openssh, 32 | openssh_can_be_verified 33 | ], 34 | Hashes = [sha256, sha512], 35 | HashTests = [{Hash, [parallel], Tests} || Hash <- Hashes], 36 | Algos = [ed25519, rsa2048, rsa3072, rsa4096], 37 | [{Algo, [parallel], HashTests} || Algo <- Algos]. 38 | 39 | init_per_group(basic, Config) -> 40 | Config; 41 | init_per_group(GroupName, Config) when 42 | GroupName =:= sha256; GroupName =:= sha512 43 | -> 44 | [{hash, GroupName} | Config]; 45 | init_per_group(GroupName, Config) when 46 | GroupName =:= ed25519; 47 | GroupName =:= rsa2048; 48 | GroupName =:= rsa3072; 49 | GroupName =:= rsa4096 50 | -> 51 | try 52 | Key = create_key(GroupName), 53 | ct:log("Key = ~p.", [Key]), 54 | [{key, Key}, {algo, GroupName} | Config] 55 | catch 56 | _C:_R:_S -> 57 | {skip, "Algorithm not supported"} 58 | end. 59 | 60 | create_key(ed25519) -> 61 | public_key:generate_key({namedCurve, ?'id-Ed25519'}); 62 | create_key(ed448) -> 63 | public_key:generate_key({namedCurve, ?'id-Ed448'}); 64 | create_key(rsa2048) -> 65 | public_key:generate_key({rsa, 2048, 3}); 66 | create_key(rsa3072) -> 67 | public_key:generate_key({rsa, 3072, 3}); 68 | create_key(rsa4096) -> 69 | public_key:generate_key({rsa, 4096, 3}). 70 | 71 | end_per_group(_, Config) -> 72 | Config. 73 | 74 | can_verify_signed(Config) -> 75 | Key = ?config(key, Config), 76 | Hash = ?config(hash, Config), 77 | Data = crypto:strong_rand_bytes(256), 78 | 79 | PubKey = ssh_signature:priv_to_public(Key), 80 | 81 | Signature = ssh_signature:sign(Data, Key, <<"file">>, #{hash => Hash}), 82 | ct:log("Signature = ~s.", [Signature]), 83 | 84 | ?assertMatch( 85 | {ok, #{public_key := PubKey}}, ssh_signature:verify(Data, Signature) 86 | ). 87 | 88 | signature_can_be_verified_by_openssh(Config) -> 89 | ct:make_priv_dir(), 90 | Key = ?config(key, Config), 91 | Hash = ?config(hash, Config), 92 | PrivDir = ?config(priv_dir, Config), 93 | 94 | DataFile = filename:join(PrivDir, "data"), 95 | AllowedSignersFile = filename:join(PrivDir, "key"), 96 | SigFile = filename:join(PrivDir, "data.sig"), 97 | 98 | Data = crypto:strong_rand_bytes(256), 99 | ExportedKey = encode([{ssh_signature:priv_to_public(Key), []}]), 100 | 101 | Signature = ssh_signature:sign(Data, Key, <<"file">>, #{hash => Hash}), 102 | 103 | ct:log("DataB64 = ~s.", [base64:encode(Data)]), 104 | ct:log("ExportedKey = ~s.", [ExportedKey]), 105 | ct:log("Signature = ~s.", [Signature]), 106 | file:write_file(DataFile, Data), 107 | file:write_file(AllowedSignersFile, ["test@example.com ", ExportedKey]), 108 | file:write_file(SigFile, Signature), 109 | 110 | ?assert( 111 | ssh_keygen( 112 | [ 113 | "-Y", 114 | "verify", 115 | "-n", 116 | "file", 117 | "-f", 118 | AllowedSignersFile, 119 | "-I", 120 | "test@example.com", 121 | "-s", 122 | SigFile 123 | ], 124 | Data 125 | ) 126 | ), 127 | 128 | Config. 129 | 130 | openssh_can_be_verified(Config) -> 131 | ct:make_priv_dir(), 132 | Algo = ?config(algo, Config), 133 | Hash = ?config(hash, Config), 134 | PrivDir = ?config(priv_dir, Config), 135 | 136 | PrivKeyFile = filename:join(PrivDir, "key"), 137 | PubKeyFile = filename:join(PrivDir, "key.pub"), 138 | DataFile = filename:join(PrivDir, "data"), 139 | SigFile = filename:join(PrivDir, "data.sig"), 140 | 141 | {Type, ExtraArgs} = openssh_keygen_args(Algo, Hash), 142 | true = ssh_keygen( 143 | ["-t", Type, "-f", PrivKeyFile, "-N", ""] ++ ExtraArgs, "" 144 | ), 145 | 146 | {ok, PubKeyPEM} = file:read_file(PubKeyFile), 147 | 148 | ct:log("PubKeyPEM = ~s.", [PubKeyPEM]), 149 | 150 | Data = crypto:strong_rand_bytes(256), 151 | ct:log("Data = ~s.", [base64:encode(Data)]), 152 | file:write_file(DataFile, Data), 153 | 154 | [{PK, _}] = decode(PubKeyPEM), 155 | 156 | true = ssh_keygen( 157 | ["-Y", "sign", "-f", PrivKeyFile, "-n", "test", DataFile], "" 158 | ), 159 | 160 | {ok, Signature} = file:read_file(SigFile), 161 | 162 | {ok, Result} = ssh_signature:verify(Data, Signature), 163 | ?assertMatch(#{public_key := PK}, Result), 164 | 165 | Config. 166 | 167 | openssh_keygen_args(ed25519, _) -> {"ed25519", []}; 168 | openssh_keygen_args(rsa2048, H) -> {rsa(H), ["-b", "2048"]}; 169 | openssh_keygen_args(rsa3072, H) -> {rsa(H), ["-b", "3072"]}; 170 | openssh_keygen_args(rsa4096, H) -> {rsa(H), ["-b", "4096"]}. 171 | 172 | rsa(sha256) -> "rsa-sha2-256"; 173 | rsa(sha512) -> "rsa-sha2-512". 174 | 175 | ssh_keygen(Args, Input) -> 176 | Stdout = fun(_, _, Data) -> 177 | ct:pal("ssh-keygen -> ~s", [Data]) 178 | end, 179 | exec:start(), 180 | Exec = os:find_executable("ssh-keygen"), 181 | {ok, Pid, _OsPid} = exec:run([Exec | Args], [ 182 | stdin, monitor, {stdout, Stdout} 183 | ]), 184 | case string:is_empty(Input) of 185 | false -> 186 | exec:send(Pid, Input), 187 | exec:send(Pid, eof); 188 | true -> 189 | ok 190 | end, 191 | receive 192 | {'DOWN', _, process, _, normal} -> 193 | true 194 | after 2000 -> 195 | false 196 | end. 197 | 198 | -if(?OTP_RELEASE < 24). 199 | encode(Key) -> 200 | public_key:ssh_encode(Key, openssh_public_key). 201 | 202 | decode(Key) -> 203 | public_key:ssh_decode(Key, openssh_public_key). 204 | -else. 205 | encode(Key) -> 206 | ssh_file:encode(Key, openssh_key). 207 | 208 | decode(Key) -> 209 | ssh_file:decode(Key, openssh_key). 210 | -endif. 211 | --------------------------------------------------------------------------------