├── .gitignore ├── wild.json ├── stack.yaml ├── release.sh ├── lib ├── Unbreak │ ├── Pack.hs │ ├── Format.hs │ ├── Crypto.hs │ └── Run.hs └── Data │ └── ByteString │ └── OverheadFree.hs ├── CHANGELOG.md ├── src └── Main.hs ├── unbreak.cabal ├── README.md └── LICENSE /.gitignore: -------------------------------------------------------------------------------- 1 | .stack-work/* 2 | -------------------------------------------------------------------------------- /wild.json: -------------------------------------------------------------------------------- 1 | { 2 | "owner": "kinoru", 3 | "repo": "unbreak", 4 | "tokenPath": "~/.github.token" 5 | } 6 | -------------------------------------------------------------------------------- /stack.yaml: -------------------------------------------------------------------------------- 1 | flags: {} 2 | extra-package-dbs: [] 3 | packages: 4 | - '.' 5 | extra-deps: [] 6 | resolver: nightly-2017-12-10 7 | -------------------------------------------------------------------------------- /release.sh: -------------------------------------------------------------------------------- 1 | # run before release. 2 | strip --strip-all --remove-section=.comment --remove-section=.note ~/.local/bin/unbreak && upx -9 ~/.local/bin/unbreak 3 | -------------------------------------------------------------------------------- /lib/Unbreak/Pack.hs: -------------------------------------------------------------------------------- 1 | module Unbreak.Pack 2 | ( str 3 | , int 4 | ) where 5 | 6 | import Data.ByteString (ByteString) 7 | import qualified Data.ByteString.Lazy as LB 8 | import qualified Data.ByteString.Builder as B 9 | 10 | str :: String -> ByteString 11 | str = LB.toStrict . B.toLazyByteString . B.stringUtf8 12 | 13 | int :: Int -> ByteString 14 | int = LB.toStrict . B.toLazyByteString . B.intDec 15 | -------------------------------------------------------------------------------- /lib/Unbreak/Format.hs: -------------------------------------------------------------------------------- 1 | {-# LANGUAGE DeriveGeneric #-} 2 | 3 | module Unbreak.Format 4 | ( FromJSON(..) 5 | , dec 6 | , EncodeJSON(..) 7 | , Conf(..) 8 | , initConf 9 | ) where 10 | 11 | import Data.Text 12 | import Data.ByteString (ByteString) 13 | import Data.ByteString.Lazy (fromStrict, toStrict) 14 | 15 | import GHC.Generics (Generic) 16 | import Data.Aeson 17 | import Data.Aeson.Encode.Pretty 18 | 19 | dec :: FromJSON a => ByteString -> Either String a 20 | dec = eitherDecode . fromStrict 21 | 22 | encBase :: ToJSON a => [Text] -> a -> ByteString 23 | encBase keys = (toStrict .) $ encodePretty' defConfig 24 | { confIndent = Spaces 2 25 | , confCompare = keyOrder keys 26 | } 27 | 28 | -- a separate class for explicit ordering of JSON fields 29 | class EncodeJSON a where 30 | enc :: a -> ByteString 31 | 32 | data Conf = Conf 33 | { name :: !Text 34 | , remote :: !Text 35 | , editor :: !Text 36 | } 37 | deriving (Show, Generic) 38 | 39 | instance FromJSON Conf 40 | instance ToJSON Conf 41 | instance EncodeJSON Conf where 42 | enc = encBase ["name", "remote", "editor"] 43 | 44 | initConf :: Conf 45 | initConf = Conf 46 | "Your Name (or anything correctly memorable)" 47 | "username@example.com:path/to/docdir/" 48 | "vim" 49 | -------------------------------------------------------------------------------- /lib/Data/ByteString/OverheadFree.hs: -------------------------------------------------------------------------------- 1 | -- | 2 | -- Module : Data.ByteString.OverheadFree 3 | -- License : AGPL-3 4 | -- Maintainer : XT 5 | -- Stability : Temporary 6 | -- Portability : POSIX 7 | -- 8 | -- This module is intended to be a drop-in replacement of 9 | -- "Data.ByteString.Char8". 10 | -- 11 | -- The only two functions whose type signatures have changed are 'readFile' 12 | -- and 'writeFile'. They take 'RawFilePath' instead of 'FilePath'. This is 13 | -- to avoid the unnecessary 'String' - 'ByteString' conversion overhead. 14 | -- 15 | -- The ongoing 16 | -- 17 | -- should address this issue, so this is a 18 | -- temporary resolution until the proposal is merged. 19 | -- 20 | module Data.ByteString.OverheadFree 21 | ( readFile 22 | , writeFile 23 | , module Data.ByteString.Char8 24 | ) where 25 | 26 | import Prelude hiding (readFile, writeFile) 27 | import Control.Exception (bracket) 28 | import System.IO (hClose) 29 | import Data.ByteString.Char8 hiding (readFile, writeFile) 30 | import qualified Data.ByteString as B 31 | import System.Posix.ByteString 32 | 33 | defaultFlags :: OpenFileFlags 34 | defaultFlags = OpenFileFlags 35 | { append = False 36 | , exclusive = False 37 | , noctty = True 38 | , nonBlock = False 39 | , trunc = False 40 | } 41 | 42 | -- | Read an entire file at the 'RawFilePath' strictly into a 'ByteString'. 43 | readFile :: RawFilePath -> IO ByteString 44 | readFile path = bracket open hClose B.hGetContents 45 | where 46 | open = openFd path ReadOnly Nothing defaultFlags >>= fdToHandle 47 | 48 | -- | Write a 'ByteString' to a file at the 'RawFilePath'. 49 | writeFile :: RawFilePath -> ByteString -> IO () 50 | writeFile path content = bracket open hClose (`B.hPut` content) 51 | where 52 | open = createFile path dfm >>= fdToHandle 53 | dfm = unionFileModes ownerReadMode ownerWriteMode 54 | -------------------------------------------------------------------------------- /CHANGELOG.md: -------------------------------------------------------------------------------- 1 | # Change Log 2 | 3 | ## 0.5.0 - 2018-01-05 4 | 5 | - Added support for custom editor command line options. Before this, "editor" could only be a single command like `gedit`. With the support, "editor" can be `gedit -w`. 6 | 7 | ## 0.4.0 - 2017-08-27 8 | 9 | - Added "cat" command: prints out the file content, good for Unix pipe chaining 10 | 11 | ## 0.3.1 - 2015-12-30 12 | 13 | - Changed wrong error messages and improved existing messages. 14 | - Added necessary fields to unbreak.cabal. 15 | - Applied [wild](https://github.com/xtendo-org/wild). 16 | 17 | ## 0.3.0 - 2015-12-15 18 | 19 | - The command line arguments interface has changed to multi-mode. Users are now advised to set `u` as an alias of `unbreak open`. 20 | - `unbreak init` 21 | - `unbreak open ` 22 | - `unbreak logout` 23 | - `unbreak add [OPTIONS] ` 24 | - Added `unbreak add`: Pick a local file, encrypt it, and put it in the remote storage 25 | - Added `unbreak logout`: Explicitly remove the session files from the memory space. 26 | - Added automatic removal of local temporary files in the memory space after `unbreapk open`. 27 | - Added upload error remedy to `unbreak open`: the user's effort won't be immediately lost even when the upload fails. Now there is a chance to retry or save it somewhere else. 28 | - Fixed file name encryption: Very silly elementary cryptographic mistake. Eliminated the chance of adversary guessing the file name when there are multiple files with the same prefix. 29 | 30 | ## 0.2.0 - 2015-12-09 31 | 32 | - Added encryption of file names: File names may be a sensitive information as well. They are now encrypted with ChaCha20-Poly1305 and base64url-encoded. 33 | - Avoid network overhead by checking file mtype: The file won't be sent if it hasn't been changed. 34 | 35 | ## 0.1.0 - 2015-12-05 36 | 37 | - Prepended a single byte in the encrypted file format to indicate the "version number." The byte isn't really used for anything useful yet; it's for forward compatibility. 38 | -------------------------------------------------------------------------------- /src/Main.hs: -------------------------------------------------------------------------------- 1 | module Main where 2 | 3 | import Data.ByteString (ByteString) 4 | import qualified Data.ByteString as B 5 | import qualified Data.ByteString.Lazy as LB 6 | import qualified Data.ByteString.Builder as B 7 | import System.Console.CmdArgs.Explicit 8 | 9 | import Unbreak.Run 10 | 11 | pack :: String -> ByteString 12 | pack = LB.toStrict . B.toLazyByteString . B.stringUtf8 13 | 14 | data Cmd 15 | = CmdInit 16 | | CmdCat ByteString 17 | | CmdOpen ByteString 18 | | CmdLogout 19 | | CmdAdd 20 | Bool -- ^ force overwrite or not 21 | ByteString 22 | | CmdList 23 | | CmdHelp 24 | 25 | modeInit :: Mode Cmd 26 | modeInit = mode "init" CmdInit "create the default config file" 27 | (flagArg (\_ c -> Right c) "") [] 28 | 29 | modeOpen :: Mode Cmd 30 | modeOpen = mode "open" (CmdOpen "") "open a remote encrypted file" 31 | (flagArg argUpd "FILENAME") [] 32 | where 33 | argUpd a _ = Right $ CmdOpen (pack a) 34 | 35 | modeLogout :: Mode Cmd 36 | modeLogout = mode "logout" CmdLogout "delete the current session" 37 | (flagArg (\_ c -> Right c) "") [] 38 | 39 | modeAdd :: Mode Cmd 40 | modeAdd = mode "add" (CmdAdd False "") "encrypt a file and store it remotely" 41 | (flagArg argUpd "FILENAME") 42 | [flagNone ["force", "f"] forceUpd "force overwrite existing file"] 43 | where 44 | argUpd a (CmdAdd f _) = Right $ CmdAdd f (pack a) 45 | argUpd a _ = Right $ CmdAdd False (pack a) 46 | forceUpd (CmdAdd _ s) = CmdAdd True s 47 | forceUpd _ = undefined 48 | 49 | modeList :: Mode Cmd 50 | modeList = mode "list" CmdList "list the files in the remote storage" 51 | (flagArg (\_ c -> Right c) "") [] 52 | 53 | modeCat :: Mode Cmd 54 | modeCat = mode "cat" CmdList "print a remote encrypted file" 55 | (flagArg argUpd "FILENAME") [] 56 | where 57 | argUpd a _ = Right $ CmdCat (pack a) 58 | 59 | arguments :: Mode Cmd 60 | arguments = modes "unbreak" CmdHelp 61 | "remote, accessible, and encrypted file storage utility" 62 | [modeInit, modeOpen, modeLogout, modeAdd, modeList, modeCat] 63 | 64 | main :: IO () 65 | main = do 66 | args <- processArgs arguments 67 | case args of 68 | CmdHelp -> print $ helpText [] HelpFormatDefault arguments 69 | CmdInit -> runInit 70 | CmdCat b -> runCat b 71 | CmdOpen b -> if B.length b == 0 72 | then error "file name can't be empty" 73 | else runOpen Nothing b 74 | CmdLogout -> runLogout 75 | CmdAdd f b -> if B.length b == 0 76 | then error "file name can't be empty" 77 | else runAdd f b 78 | CmdList -> runList 79 | -------------------------------------------------------------------------------- /unbreak.cabal: -------------------------------------------------------------------------------- 1 | name: unbreak 2 | version: 0.5.0 3 | synopsis: Secure and resilient remote file storage utility 4 | description: 5 | unbreak is a secure remote file storage utility written in Haskell. 6 | . 7 | Other than a working SSH server and an empty directory, it requires no 8 | configuration on the server-side to set up the file storage. Leveraging 9 | existing commands, it simplifies the process of fetching and saving files 10 | with a client-side encryption. It aims to make the work flow natural, as 11 | if the user is using an unencrypted local file, while keeping the 12 | local-remote interaction as rare as possible to be usable even with a 13 | highly unstable Internet connection. 14 | . 15 | unbreak uses modern crypto primitives such as scrypt and ChaCha20-Poly1305 16 | to protect user security and privacy. Some of its usage is documented in 17 | the 'Unbreak.Crypto' module. The API is internal and you should not 18 | directly depend on them from your code, but browsing the source code from 19 | the API docs and copying them to adapt to another free software is 20 | highly encouraged. 21 | . 22 | For a detailed information on how to actually use this utility, please 23 | refer to its official web page at . 24 | license: AGPL-3 25 | license-file: LICENSE 26 | author: XT 27 | maintainer: e@xtendo.org 28 | copyright: Copyright (C) 2015-2017 XT 29 | category: Network 30 | build-type: Simple 31 | cabal-version: >=1.18 32 | homepage: https://e.xtendo.org/scs/unbreak 33 | bug-reports: https://github.com/xtendo-org/unbreak/issues 34 | tested-with: GHC==7.10.2 35 | extra-source-files: README.md CHANGELOG.md 36 | 37 | library 38 | hs-source-dirs: lib 39 | exposed-modules: 40 | Unbreak.Crypto, 41 | Unbreak.Format, 42 | Unbreak.Run, 43 | Data.ByteString.OverheadFree 44 | other-modules: 45 | Unbreak.Pack 46 | default-extensions: OverloadedStrings, RecordWildCards 47 | default-language: Haskell2010 48 | build-depends: 49 | aeson, 50 | aeson-pretty, 51 | base64-bytestring, 52 | bytestring, 53 | cereal, 54 | cryptonite, 55 | memory, 56 | text, 57 | unix, 58 | base 59 | ghc-options: -Wall -fwarn-incomplete-uni-patterns 60 | 61 | executable unbreak 62 | default-extensions: OverloadedStrings, RecordWildCards 63 | main-is: Main.hs 64 | hs-source-dirs: src 65 | build-depends: 66 | bytestring >= 0.10, 67 | cmdargs >= 0.10, 68 | unbreak, 69 | base >=4.8 && <5 70 | ghc-options: -Wall -fwarn-incomplete-uni-patterns -O2 -threaded -static 71 | default-language: Haskell2010 72 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | **unbreak** is a tool that lets you have a secure and resilient remote file storage. 2 | 3 | Current version: **0.5.0** ([change log](https://github.com/xtendo-org/unbreak/blob/master/CHANGELOG.md)) 4 | 5 | unbreak is released under AGPL-3. Questions, bug reports, feature requests, and pull requests are highly welcome. 6 | 7 | ## Advantages 8 | 9 | - Zero setup on the server side: You only need a working SSH server and an empty directory. 10 | - Extremely little setup on the client side: You only need a single executable and a short configuration file. 11 | - Client-side encryption: Unless your client system is stolen, it is nearly impossible for anyone else to guess what's in your storage, even for the VPS providers like Google, Amazon, etc. 12 | - Resilience to connection instability: You can move your laptop around, suspend it, change the IP address, and unbreak will work fine, hence the name. 13 | 14 | ## In a nutshell 15 | 16 | 1. You type `u cheatsheet.txt` 17 | 1. You start editing your cheat sheet text file. 18 | 1. You save and quit. 19 | 1. The edited file is encrypted and stored remotely. 20 | 21 | ## Installation 22 | 23 | One binary file for x64 GNU/Linux. 24 | 25 | ```bash 26 | curl -L \ 27 | https://github.com/xtendo-org/unbreak/releases/download/v0.5.0/unbreak \ 28 | > ~/.local/bin/unbreak \ 29 | && chmod +x ~/.local/bin/unbreak 30 | ``` 31 | 32 | (Assuming `~/.local/bin` exists and is in your `$PATH`.) 33 | 34 | You are also recommended to set alias `u` for `unbreak open`. Include in your shell configuration (`~/.bashrc` by default): 35 | 36 | ```bash 37 | alias u="unbreak open" 38 | ``` 39 | 40 | ### Requirements 41 | 42 | For the `unbreak` executable to properly run, The following must be available on the client system. 43 | 44 | - `/dev/urandom` 45 | - `mktemp` 46 | - `/dev/shm` (the default shared memory space) writable by you 47 | - `ssh` and `scp` 48 | - The `$HOME` environment variable 49 | 50 | In other words, it will probably work on any ordinary x64 GNU/Linux distribution. Support for other POSIX systems (such as BSD or OS X) is planned. 51 | 52 | ### Build from source 53 | 54 | - [Stack](http://haskellstack.org/) is the recommended method to build the latest development version of unbreak. 55 | 56 | ```bash 57 | $ git clone --depth=1 https://github.com/xtendo-org/unbreak 58 | $ cd unbreak 59 | $ stack install 60 | ``` 61 | 62 | ## Usage 63 | 64 | Run `unbreak init` and the file `~/.unbreak.json` will be created with default configuration. Edit it and configure unbreak. 65 | 66 | - `name`: This works as a salt to fight against the rainbow table attack to generate the master secret key. It's a salt, so it doesn't have to be secret. Just pick something memorable and unique. [xkcd offers a brilliant advice](https://xkcd.com/936/). 67 | - `remote`: The path of the remote directory that will serve as a storage of all documents. (For now, it must exist.) The document name will be appended to this path when it is passed to the `scp` command. 68 | - `editor`: The default value is [`vim`](https://e.xtendo.org/scs/vim). 69 | 70 | Now you type `u cheatsheet.txt` to actually begin editing a file. Since this is your first time using unbreak and there is no session yet, you'll be asked to type a password that will be used to generate the master key (along with the salt in `~/.unbreak.json`). The master key is stored under `/dev/shm` during the session. 71 | 72 | ## How it works 73 | 74 | 1. You type `u cheatsheet.txt` 75 | 1. Download the encrypted file from the remote storage with `scp`. 76 | 1. Decrypt the file with your master key and save it temporarily as `cheatsheet.txt` 77 | 1. Open this file with your chosen editor. 78 | 1. You edit your cheat sheet text file with your favorite text editor. 79 | 1. You save and quit. 80 | 1. Encrypt the file with your master key and save it temporarily as `YLfZ9XA4YGYNRykW4Ns=` 81 | 1. Upload the encrypted file to the remote storage with `scp`. 82 | 1. Clean up the files and terminate. 83 | 84 | ## Why? 85 | 86 | Recently a type of operating system instances became very common. They are 87 | 88 | - not maintained (in terms of electricity supply, thermal control, Internet connection, etc.) by you 89 | - not in your vicinity 90 | - not under your ownership 91 | 92 | Some people seem to prefer the term "cloud." 93 | 94 | What you want to do is, in the terminal, you would type `u comic.zip` and a comic book viewer will let you read the comic book that is encrypted and stored remotely. Or `u cheatsheet.txt` will open a text editor and let you edit your cheat sheet text file. After a while you will save and quit, then the document will be encrypted and stored in the remote operating system instance. Certain conditions apply: 95 | 96 | - You want the whole process be resilient to an **unstable Internet connection**. Bringing your laptop around or even suspending it breaks the connection, so you want it to require the connection only when it's needed, that is, the opening and saving moment. 97 | - Following the spirit of the excellent [Tarsnap](https://www.tarsnap.com/) service, you want the **client-side encryption** before the file is sent to the remote system. The notion that you have _your_ instance in the "cloud" is an illusion; the company that runs this "cloud" service has a full technical (and, in many cases, even legal) access to your data. 98 | 99 | Alternatives all fell short: 100 | 101 | - Saving locally with full-disk encryption: The data becomes inaccessible from different (home/office) computers. 102 | - sshfs: Very good, and very fragile with an unstable Internet connection. Sometimes it makes the whole I/O hang. (You have to manually `umount` with `-l` option.) 103 | - Vim with netrw scp support: Can't encrypt/decrypt with a modern cipher like ChaCha20, unless you learn Vimscript and write a plugin of your own. Some editors don't even have the scripting feature at all. 104 | -------------------------------------------------------------------------------- /lib/Unbreak/Crypto.hs: -------------------------------------------------------------------------------- 1 | -- | 2 | -- Module : Unbreak.Crypto 3 | -- License : AGPL-3 4 | -- Maintainer : XT 5 | -- Stability : Provisional 6 | -- Portability : POSIX 7 | -- 8 | -- Simple interface to the cryptographic primitives that are provided by 9 | -- the package. 10 | module Unbreak.Crypto 11 | ( getRandomBytes 12 | , scrypt 13 | , encrypt 14 | , decrypt 15 | , encryptFileName 16 | , decryptFileName 17 | , module Crypto.Error 18 | ) where 19 | 20 | import Prelude hiding ((++)) 21 | import System.IO 22 | import Data.ByteString (ByteString, hGet) 23 | import qualified Data.ByteString.Char8 as B 24 | import qualified Data.ByteString.Lazy as LB 25 | import qualified Data.ByteString.Builder as B 26 | import Data.Serialize.Get 27 | 28 | import Data.ByteArray (convert) 29 | import Crypto.Error 30 | import Crypto.KDF.Scrypt 31 | import qualified Crypto.Cipher.ChaChaPoly1305 as C 32 | 33 | (++) :: Monoid m => m -> m -> m 34 | (++) = mappend 35 | 36 | -- | Read bytes from @\/dev\/urandom@. 37 | getRandomBytes :: Int -> IO ByteString 38 | getRandomBytes n = withFile "/dev/urandom" ReadMode $ \ h -> hGet h n 39 | 40 | -- | The 41 | -- key derivation function from "Crypto.KDF.Scrypt". The parameters are: 42 | -- 43 | -- * CPU/memory cost parameter N = 16384 (2^14) 44 | -- * SMix function parameter r = 8 45 | -- * Parallelization parameter p = 1 46 | -- * Intended output length dkLen = 32 (for use in ChaCha20-Poly1305) 47 | scrypt 48 | :: ByteString -- ^ input 49 | -> ByteString -- ^ salt 50 | -> ByteString -- ^ output (32 bytes) 51 | scrypt = generate (Parameters 16384 8 1 32) 52 | 53 | -- | Encrypt the given 'ByteString' using the 54 | -- scheme 55 | -- from "Crypto.Cipher.ChaChaPoly1305". 56 | -- The resulting 'ByteString' is nonce (12 bytes) ++ ciphertext ++ 57 | -- the auth tag (16 bytes). 58 | encrypt 59 | :: ByteString -- ^ nonce (12 random bytes, must be different each time) 60 | -> ByteString -- ^ the secret symmetric key 61 | -> ByteString -- ^ the plaintext to be encrypted 62 | -> CryptoFailable ByteString -- ^ ciphertext with a 128-bit tag attached 63 | encrypt nonce key plaintext = (nonce ++) <$> encrypt' nonce key "" plaintext 64 | 65 | encrypt' 66 | :: ByteString -- nonce (12 random bytes) 67 | -> ByteString -- symmetric key 68 | -> ByteString -- optional associated data (won't be encrypted) 69 | -> ByteString -- input plaintext to be encrypted 70 | -> CryptoFailable ByteString -- ciphertext with a 128-bit tag attached 71 | encrypt' nonce key header plaintext = do 72 | st1 <- C.nonce12 nonce >>= C.initialize key 73 | let 74 | st2 = C.finalizeAAD $ C.appendAAD header st1 75 | (out, st3) = C.encrypt plaintext st2 76 | auth = C.finalize st3 77 | return $ out ++ Data.ByteArray.convert auth 78 | 79 | -- | Encryption of unbreak file names. 80 | encryptFileName 81 | :: ByteString -- ^ file name 82 | -> ByteString -- ^ key 83 | -> ByteString 84 | encryptFileName key fileName = nonce ++ encryptNoAuth nonce key 85 | (mconcat [word32LEencode oLen, fileName, padding]) 86 | where 87 | nonce = B.take 12 $ B.drop 10 $ scrypt fileName key 88 | oLen = B.length fileName 89 | -- 4: the length (in 32 bits) always occupies 4 bytes 90 | -- 12: the nonce always occupies 12 bytes 91 | -- -1: to make the result 48 when the input is 44, or 96 when 92, etc. 92 | goalLen = (((oLen + 15) `div` 48) + 1) * 48 93 | padding = B.pack $ replicate (goalLen - 16 - oLen) '\0' 94 | 95 | -- | Encryption without the auth tag and without the optional header. 96 | -- 'encrypt' is almost always the better choice. Use this function only when 97 | -- you know what you are doing. 98 | encryptNoAuth 99 | :: ByteString -- ^ nonce (12 random bytes) 100 | -> ByteString -- ^ the secret symmetric key 101 | -> ByteString -- ^ input plaintext to be encrypted 102 | -> ByteString -- ^ the resulting ciphertext 103 | encryptNoAuth nonce key plaintext = throwCryptoError $ do 104 | st1 <- C.nonce12 nonce >>= C.initialize key 105 | let 106 | st2 = C.finalizeAAD st1 107 | (out, _) = C.encrypt plaintext st2 108 | return out 109 | 110 | -- | Decrypt a 'ByteString' that is produced by the 'encrypt' function. 111 | decrypt 112 | :: ByteString -- ^ the secret symmetric key 113 | -> ByteString -- ^ the input (nonce ++ ciphertext ++ tag) 114 | -> CryptoFailable ByteString -- ^ the decrypted plaintext 115 | decrypt key input = decrypt' nonce key "" ciphertextWithTag 116 | where 117 | (nonce, ciphertextWithTag) = B.splitAt 12 input 118 | -- TODO: What if input is shorter than 12 119 | 120 | decrypt' 121 | :: ByteString -- the nonce used for encryption 122 | -> ByteString -- symmetric key 123 | -> ByteString -- optional associated data 124 | -> ByteString -- ciphertext with the tag attached 125 | -> CryptoFailable ByteString -- ^ decrypted plaintext 126 | decrypt' nonce key header input 127 | | B.length input < 16 = 128 | CryptoFailed CryptoError_AuthenticationTagSizeInvalid 129 | | otherwise = case decryptionAttempt of 130 | CryptoPassed (decrypted, auth) 131 | | Data.ByteArray.convert auth == tag -> return decrypted 132 | | otherwise -> CryptoFailed CryptoError_MacKeyInvalid 133 | CryptoFailed x -> CryptoFailed x 134 | where 135 | (ciphertext, tag) = B.splitAt (B.length input - 16) input 136 | decryptionAttempt = do 137 | st1 <- C.nonce12 nonce >>= C.initialize key 138 | let 139 | st2 = C.finalizeAAD $ C.appendAAD header st1 140 | (out, st3) = C.decrypt ciphertext st2 141 | auth = C.finalize st3 142 | return (out, auth) 143 | 144 | -- | Decryption of unbreak file names. 145 | decryptFileName 146 | :: ByteString 147 | -> ByteString 148 | -> ByteString 149 | decryptFileName key encrypted = B.take oLen $ B.drop 4 decrypted 150 | where 151 | (nonce, ciphertext) = B.splitAt 12 encrypted 152 | decrypted = decryptNoAuth nonce key ciphertext 153 | oLen = word32LEdecode decrypted 154 | 155 | -- | Decryption without the auth tag checking. 156 | decryptNoAuth 157 | :: ByteString -- ^ the nonce used for encryption 158 | -> ByteString -- ^ the secret symmetric key 159 | -> ByteString -- ^ input ciphertext to be decrypted 160 | -> ByteString -- ^ the resulting plaintext 161 | decryptNoAuth nonce key ciphertext = throwCryptoError $ do 162 | st1 <- C.nonce12 nonce >>= C.initialize key 163 | let 164 | st2 = C.finalizeAAD st1 165 | (out, _) = C.decrypt ciphertext st2 166 | return out 167 | 168 | word32LEencode :: Int -> ByteString 169 | word32LEencode = LB.toStrict . B.toLazyByteString . B.word32LE . fromIntegral 170 | 171 | word32LEdecode :: ByteString -> Int 172 | word32LEdecode = fromIntegral . 173 | either (const $ error "word32LE decode fail") id . 174 | runGet getWord32le 175 | -------------------------------------------------------------------------------- /lib/Unbreak/Run.hs: -------------------------------------------------------------------------------- 1 | -- | 2 | -- Module : Unbreak.Run 3 | -- License : AGPL-3 4 | -- Maintainer : XT 5 | -- Stability : Provisional 6 | -- Portability : POSIX 7 | -- 8 | -- Functions that perform the action of the Unbreak utility. 9 | module Unbreak.Run 10 | ( runInit 11 | , runOpen 12 | , runCat 13 | , runLogout 14 | , runAdd 15 | , runList 16 | ) where 17 | 18 | import Prelude hiding ((++)) 19 | import Data.Maybe 20 | import Control.Monad 21 | import Control.Exception 22 | import System.IO 23 | import System.IO.Error 24 | import System.Exit 25 | 26 | import System.Posix.ByteString 27 | 28 | import Data.ByteString (ByteString) 29 | import qualified Data.ByteString.Base64.URL as B64 30 | import qualified Data.ByteString.OverheadFree as B 31 | import qualified Data.Text as T 32 | import qualified Data.Text.Encoding as T 33 | 34 | import Unbreak.Crypto 35 | import Unbreak.Format 36 | import Unbreak.Pack 37 | 38 | (++) :: Monoid m => m -> m -> m 39 | (++) = mappend 40 | 41 | data Session = Session 42 | { shelfPath :: !ByteString 43 | , master :: !ByteString 44 | } 45 | 46 | sessionPath :: ByteString 47 | sessionPath = "/tmp/unbreak.session" 48 | 49 | getHomePath :: IO ByteString 50 | getHomePath = getEnv "HOME" >>= \ m -> case m of 51 | Nothing -> error "$HOME not found" 52 | Just h -> return h 53 | 54 | -- | Creates the @~\/.unbreak.json@ file with the default configuration 55 | -- if it's missing. 56 | runInit :: IO () 57 | runInit = do 58 | confPath <- (++ "/.unbreak.json") <$> getHomePath 59 | existence <- fileExist confPath 60 | if existence 61 | then B.putStrLn "The file ~/.unbreak.json already exists.\ 62 | \ If you are willing to create the default config file,\ 63 | \ please delete ~/.unbreak.json and retry.\n\ 64 | \CAUTION: the \"name\" part of the config may be required to open\ 65 | \ the documents you have created in the past." 66 | else do 67 | B.writeFile confPath (enc initConf) 68 | B.putStrLn $ "Created the initial default configuration at " ++ 69 | confPath 70 | 71 | -- idempotent session 72 | session :: Conf -> IO Session 73 | session Conf{..} = catchIOError 74 | -- get existing session 75 | ( do 76 | thisShelfPath <- B.readFile sessionPath 77 | thisMaster <- B.readFile (thisShelfPath ++ "/thisMaster") 78 | return $ Session thisShelfPath thisMaster 79 | ) 80 | -- or if that fails, create a new session 81 | $ const $ do 82 | thisShelfPath <- mkdtemp "/dev/shm/unbreak-" 83 | B.writeFile sessionPath thisShelfPath 84 | B.putStr "Type password: " 85 | password <- withNoEcho B.getLine <* B.putStrLn "" 86 | let thisMaster = scrypt password (T.encodeUtf8 name) 87 | B.writeFile (thisShelfPath ++ "/thisMaster") thisMaster 88 | createDirectory (thisShelfPath ++ "/file") 0o700 89 | return $ Session thisShelfPath thisMaster 90 | 91 | -- | Given a filename, try copying the file from the remote to a temporary 92 | -- shared memory space, open it with the text editor specified in the config 93 | -- file, and copy it back to the remote. Shell command @scp@ must exist. 94 | runOpen :: Maybe ByteString -> ByteString -> IO () 95 | runOpen program filename = getConf f (editRemoteFile program filename) 96 | where 97 | f errmsg = B.putStrLn ("Failed: " ++ errmsg) *> exitFailure 98 | 99 | getConf :: (ByteString -> IO a) -> (Conf -> Session -> IO a) -> IO a 100 | getConf failure success = do 101 | confPath <- (++ "/.unbreak.json") <$> getHomePath 102 | existence <- fileExist confPath 103 | if existence 104 | then do 105 | rawConf <- B.readFile confPath 106 | case dec rawConf of 107 | Left errmsg -> failure $ str errmsg 108 | Right conf -> session conf >>= success conf 109 | else do 110 | B.putStrLn "You may need to run 'unbreak init' first." 111 | failure "~/.unbreak.json does not exist" 112 | 113 | editRemoteFile :: Maybe ByteString -> ByteString -> Conf -> Session -> IO () 114 | editRemoteFile program fileName Conf{..} Session{..} = do 115 | -- copy the remote file to the shelf 116 | tryRun "scp" [remoteFilePath, encFilePath] 117 | -- if there is a file, decrypt it 118 | ( decrypt master <$> B.tail <$> B.readFile encFilePath >>= 119 | \ m -> case m of 120 | CryptoPassed plaintext -> B.writeFile filePath plaintext 121 | CryptoFailed e -> do 122 | B.putStrLn $ "Decryption failed. " ++ str (show e) 123 | exitFailure 124 | ) 125 | -- or open a new file 126 | $ \ _ -> do 127 | B.putStrLn "Create new file." 128 | B.writeFile filePath "" 129 | -- record the current time 130 | before <- epochTime 131 | -- edit the file in the shelf 132 | run (fromMaybe (T.encodeUtf8 editorCmd) program) 133 | (map T.encodeUtf8 editorOpts ++ [filePath]) 134 | $ const $ do 135 | B.putStrLn "Editor exited abnormally. Editing cancelled." 136 | exitFailure 137 | -- check mtime to see if the file has been modified 138 | after <- modificationTime <$> getFileStatus filePath 139 | when (before < after) $ do 140 | -- encrypt the file 141 | encryptCopy master filePath encFilePath 142 | -- upload the file from the shelf to the remote 143 | run "scp" [encFilePath, remoteFilePath] $ 144 | \ n -> do 145 | B.putStrLn $ mconcat 146 | [ "[!] Upload failed. (" 147 | , int n 148 | , ")\nYour file is at:\n\n\t" 149 | , filePath 150 | , "\n\nIf you want to retry upload, try:\n\n\t" 151 | , "unbreak add -f " 152 | , filePath 153 | , "\n" 154 | ] 155 | removeLink encFilePath 156 | exitFailure 157 | removeLink encFilePath 158 | removeLink filePath 159 | B.putStrLn "Done." 160 | where 161 | encFileName = B64.encode $ encryptFileName master fileName 162 | filePath = mconcat [shelfPath, "/file/", fileName] 163 | encFilePath = mconcat [shelfPath, "/file/", encFileName] 164 | remoteFilePath = mconcat [T.encodeUtf8 remote, encFileName] 165 | (editorCmd, editorOpts) = case T.split (== ' ') editor of 166 | [] -> ("vim", []) 167 | x : xs -> (x, xs) 168 | 169 | 170 | runCat :: ByteString -> IO () 171 | runCat fileName = getConf f (catRemoteFile fileName) 172 | where 173 | f errmsg = B.putStrLn ("Failed: " ++ errmsg) *> exitFailure 174 | 175 | 176 | catRemoteFile :: ByteString -> Conf -> Session -> IO () 177 | catRemoteFile fileName Conf{..} Session{..} = 178 | tryRun "scp" [remoteFilePath, encFilePath] successCase failCase 179 | where 180 | successCase = decrypt master <$> B.tail <$> B.readFile encFilePath >>= 181 | \ m -> case m of 182 | CryptoPassed plaintext -> B.putStr plaintext 183 | CryptoFailed e -> do 184 | B.putStrLn $ "Decryption failed. " ++ str (show e) 185 | exitFailure 186 | failCase _ = B.putStrLn "File not found." >> exitFailure 187 | encFileName = B64.encode $ encryptFileName master fileName 188 | encFilePath = mconcat [shelfPath, "/file/", encFileName] 189 | remoteFilePath = mconcat [T.encodeUtf8 remote, encFileName] 190 | 191 | 192 | runLogout :: IO () 193 | runLogout = do 194 | shelfPath <- catchIOError (B.readFile sessionPath) $ \ e -> do 195 | if isDoesNotExistError e 196 | then B.putStrLn "You are not logged in." 197 | else B.putStrLn $ mconcat 198 | [ "Reading " 199 | , sessionPath 200 | , " has failed. (" 201 | , str $ show e 202 | , ") Perhaps there is no active session?" 203 | ] 204 | exitFailure 205 | -- TODO: replace this with a more sensible system call 206 | run "rm" ["-rf", shelfPath] $ \ errorCode -> B.putStrLn $ mconcat 207 | [ "[!] Removing the session directory at " 208 | , shelfPath 209 | , " failed! (" 210 | , int errorCode 211 | , ") Please manually delete it." 212 | ] 213 | removeLink sessionPath 214 | 215 | -- | Pick a local file, encrypt it, and send to the remote storage. 216 | runAdd 217 | :: Bool -- ^ Force upload even when the file name already exists 218 | -> RawFilePath 219 | -> IO () 220 | runAdd force filePath = getConf f (encryptAndSend force filePath) 221 | where 222 | f errmsg = B.putStrLn ("Failed: " ++ errmsg) *> exitFailure 223 | 224 | encryptAndSend :: Bool -> RawFilePath -> Conf -> Session -> IO () 225 | encryptAndSend force filePath Conf{..} Session{..} = if force then action else 226 | tryRun "ssh" [host, "test", "-e", docdir ++ encFileName] 227 | (B.putStrLn msg *> exitFailure) $ const action 228 | where 229 | msg = "The file name already exists in the storage. Cancelled." 230 | remoteB = T.encodeUtf8 remote 231 | (host, docdir) = sshHost remoteB 232 | fileName = snd $ B.breakEnd (== '/') filePath 233 | encFileName = B64.encode $ encryptFileName master fileName 234 | encFilePath = mconcat [shelfPath, "/file/", encFileName] 235 | remoteFilePath = remoteB ++ encFileName 236 | action = do 237 | encryptCopy master filePath encFilePath 238 | -- upload the file from the shelf to the remote 239 | run "scp" [encFilePath, remoteFilePath] $ 240 | \ n -> B.putStrLn $ mconcat 241 | ["Upload failed. (", int n, ")"] 242 | -- cleanup: remove the local temporary file 243 | removeLink encFilePath 244 | 245 | encryptCopy :: ByteString -> RawFilePath -> RawFilePath -> IO () 246 | encryptCopy key sourcePath targetPath = do 247 | plaintext <- B.readFile sourcePath 248 | nonce <- getRandomBytes 12 249 | B.writeFile targetPath $ 250 | -- adding the version number, for forward compatibility 251 | "\0" ++ throwCryptoError (encrypt nonce key plaintext) 252 | 253 | -- | Show the list of files in the remote storage. 254 | runList :: IO () 255 | runList = getConf f withArgs 256 | where 257 | f errmsg = B.putStrLn ("Failed: " ++ errmsg) *> exitFailure 258 | withArgs Conf{..} Session{..} = do 259 | result <- runRead "ssh" [host, "ls", docdir] 260 | case result of 261 | Left c -> B.putStrLn (mconcat ["ssh ls failed. (", int c, ")"]) 262 | *> exitFailure 263 | Right b -> B.putStrLn $ B.intercalate "\n" $ 264 | map (decryptFileName master . B64.decodeLenient) $ split b 265 | where 266 | (host, docdir) = sshHost (T.encodeUtf8 remote) 267 | split = filter (/= "") . B.split '\n' 268 | 269 | -- utility functions 270 | 271 | withNoEcho :: IO a -> IO a 272 | withNoEcho action = do 273 | old <- hGetEcho stdin 274 | bracket_ (hSetEcho stdin False) (hSetEcho stdin old) action 275 | 276 | run :: RawFilePath -> [ByteString] -> (Int -> IO ()) -> IO () 277 | run cmd args = tryRun cmd args (return ()) 278 | 279 | tryRun :: RawFilePath -> [ByteString] -> IO a -> (Int -> IO a) -> IO a 280 | tryRun cmd args successHandler failHandler = do 281 | pid <- forkProcess $ executeFile cmd True args Nothing 282 | getProcessStatus True False pid >>= \ mstatus -> case mstatus of 283 | Just status -> case status of 284 | Exited exitCode -> case exitCode of 285 | ExitSuccess -> successHandler 286 | ExitFailure c -> failHandler c 287 | _ -> error $ show cmd 288 | Nothing -> error $ show cmd 289 | 290 | runRead :: RawFilePath -> [ByteString] -> IO (Either Int ByteString) 291 | runRead cmd args = do 292 | (fd0, fd1) <- createPipe 293 | pid <- forkProcess $ do 294 | closeFd fd0 295 | closeFd stdOutput 296 | void $ dupTo fd1 stdOutput 297 | executeFile cmd True args Nothing 298 | closeFd fd1 299 | content <- fdToHandle fd0 >>= B.hGetContents 300 | getProcessStatus True False pid >>= \ mstatus -> case mstatus of 301 | Just status -> case status of 302 | Exited exitCode -> case exitCode of 303 | ExitSuccess -> return $ Right content 304 | ExitFailure c -> return $ Left c 305 | _ -> error $ show cmd 306 | Nothing -> error $ show cmd 307 | 308 | sshHost :: ByteString -> (ByteString, ByteString) 309 | sshHost b = (host, docdir) 310 | where 311 | (host, cDocdir) = B.break (== ':') b 312 | docdir = if B.head cDocdir == ':' then B.tail cDocdir else cDocdir 313 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU AFFERO GENERAL PUBLIC LICENSE 2 | Version 3, 19 November 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU Affero General Public License is a free, copyleft license for 11 | software and other kinds of works, specifically designed to ensure 12 | cooperation with the community in the case of network server software. 13 | 14 | The licenses for most software and other practical works are designed 15 | to take away your freedom to share and change the works. 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Patents. 460 | 461 | A "contributor" is a copyright holder who authorizes use under this 462 | License of the Program or a work on which the Program is based. The 463 | work thus licensed is called the contributor's "contributor version". 464 | 465 | A contributor's "essential patent claims" are all patent claims 466 | owned or controlled by the contributor, whether already acquired or 467 | hereafter acquired, that would be infringed by some manner, permitted 468 | by this License, of making, using, or selling its contributor version, 469 | but do not include claims that would be infringed only as a 470 | consequence of further modification of the contributor version. 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You may not convey a covered 513 | work if you are a party to an arrangement with a third party that is 514 | in the business of distributing software, under which you make payment 515 | to the third party based on the extent of your activity of conveying 516 | the work, and under which the third party grants, to any of the 517 | parties who would receive the covered work from you, a discriminatory 518 | patent license (a) in connection with copies of the covered work 519 | conveyed by you (or copies made from those copies), or (b) primarily 520 | for and in connection with specific products or compilations that 521 | contain the covered work, unless you entered into that arrangement, 522 | or that patent license was granted, prior to 28 March 2007. 523 | 524 | Nothing in this License shall be construed as excluding or limiting 525 | any implied license or other defenses to infringement that may 526 | otherwise be available to you under applicable patent law. 527 | 528 | 12. No Surrender of Others' Freedom. 529 | 530 | If conditions are imposed on you (whether by court order, agreement or 531 | otherwise) that contradict the conditions of this License, they do not 532 | excuse you from the conditions of this License. If you cannot convey a 533 | covered work so as to satisfy simultaneously your obligations under this 534 | License and any other pertinent obligations, then as a consequence you may 535 | not convey it at all. For example, if you agree to terms that obligate you 536 | to collect a royalty for further conveying from those to whom you convey 537 | the Program, the only way you could satisfy both those terms and this 538 | License would be to refrain entirely from conveying the Program. 539 | 540 | 13. Remote Network Interaction; Use with the GNU General Public License. 541 | 542 | Notwithstanding any other provision of this License, if you modify the 543 | Program, your modified version must prominently offer all users 544 | interacting with it remotely through a computer network (if your version 545 | supports such interaction) an opportunity to receive the Corresponding 546 | Source of your version by providing access to the Corresponding Source 547 | from a network server at no charge, through some standard or customary 548 | means of facilitating copying of software. This Corresponding Source 549 | shall include the Corresponding Source for any work covered by version 3 550 | of the GNU General Public License that is incorporated pursuant to the 551 | following paragraph. 552 | 553 | Notwithstanding any other provision of this License, you have 554 | permission to link or combine any covered work with a work licensed 555 | under version 3 of the GNU General Public License into a single 556 | combined work, and to convey the resulting work. The terms of this 557 | License will continue to apply to the part which is the covered work, 558 | but the work with which it is combined will remain governed by version 559 | 3 of the GNU General Public License. 560 | 561 | 14. Revised Versions of this License. 562 | 563 | The Free Software Foundation may publish revised and/or new versions of 564 | the GNU Affero General Public License from time to time. Such new versions 565 | will be similar in spirit to the present version, but may differ in detail to 566 | address new problems or concerns. 567 | 568 | Each version is given a distinguishing version number. If the 569 | Program specifies that a certain numbered version of the GNU Affero General 570 | Public License "or any later version" applies to it, you have the 571 | option of following the terms and conditions either of that numbered 572 | version or of any later version published by the Free Software 573 | Foundation. If the Program does not specify a version number of the 574 | GNU Affero General Public License, you may choose any version ever published 575 | by the Free Software Foundation. 576 | 577 | If the Program specifies that a proxy can decide which future 578 | versions of the GNU Affero General Public License can be used, that proxy's 579 | public statement of acceptance of a version permanently authorizes you 580 | to choose that version for the Program. 581 | 582 | Later license versions may give you additional or different 583 | permissions. However, no additional obligations are imposed on any 584 | author or copyright holder as a result of your choosing to follow a 585 | later version. 586 | 587 | 15. Disclaimer of Warranty. 588 | 589 | THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY 590 | APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT 591 | HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY 592 | OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, 593 | THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 594 | PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM 595 | IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF 596 | ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 597 | 598 | 16. Limitation of Liability. 599 | 600 | IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING 601 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS 602 | THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY 603 | GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE 604 | USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF 605 | DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD 606 | PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), 607 | EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF 608 | SUCH DAMAGES. 609 | 610 | 17. Interpretation of Sections 15 and 16. 611 | 612 | If the disclaimer of warranty and limitation of liability provided 613 | above cannot be given local legal effect according to their terms, 614 | reviewing courts shall apply local law that most closely approximates 615 | an absolute waiver of all civil liability in connection with the 616 | Program, unless a warranty or assumption of liability accompanies a 617 | copy of the Program in return for a fee. 618 | 619 | END OF TERMS AND CONDITIONS 620 | 621 | How to Apply These Terms to Your New Programs 622 | 623 | If you develop a new program, and you want it to be of the greatest 624 | possible use to the public, the best way to achieve this is to make it 625 | free software which everyone can redistribute and change under these terms. 626 | 627 | To do so, attach the following notices to the program. It is safest 628 | to attach them to the start of each source file to most effectively 629 | state the exclusion of warranty; and each file should have at least 630 | the "copyright" line and a pointer to where the full notice is found. 631 | 632 | 633 | Copyright (C) 634 | 635 | This program is free software: you can redistribute it and/or modify 636 | it under the terms of the GNU Affero General Public License as published by 637 | the Free Software Foundation, either version 3 of the License, or 638 | (at your option) any later version. 639 | 640 | This program is distributed in the hope that it will be useful, 641 | but WITHOUT ANY WARRANTY; without even the implied warranty of 642 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 643 | GNU Affero General Public License for more details. 644 | 645 | You should have received a copy of the GNU Affero General Public License 646 | along with this program. If not, see . 647 | 648 | Also add information on how to contact you by electronic and paper mail. 649 | 650 | If your software can interact with users remotely through a computer 651 | network, you should also make sure that it provides a way for users to 652 | get its source. For example, if your program is a web application, its 653 | interface could display a "Source" link that leads users to an archive 654 | of the code. There are many ways you could offer source, and different 655 | solutions will be better for different programs; see section 13 for the 656 | specific requirements. 657 | 658 | You should also get your employer (if you work as a programmer) or school, 659 | if any, to sign a "copyright disclaimer" for the program, if necessary. 660 | For more information on this, and how to apply and follow the GNU AGPL, see 661 | . 662 | --------------------------------------------------------------------------------