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Crypto.hs

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+{- git-annex crypto
+ -
+ - Copyright 2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Crypto (
+	genCipher,
+	updateCipher,
+	storeCipher,
+	extractCipher,
+	decryptCipher,		
+	encryptKey,
+	encryptContent,
+	decryptContent
+) where
+
+import qualified Data.ByteString.Lazy.Char8 as L
+import qualified Data.Map as M
+import System.IO
+import System.Cmd.Utils
+
+import Types
+import RemoteClass
+import Utility
+
+data Cipher = Cipher String -- XXX ideally, this would be a locked memory region
+data EncryptedCipher = EncryptedCipher String
+	deriving Show
+
+{- Creates a new Cipher, encrypted as specified in the remote's configuration -}
+genCipher :: RemoteConfig -> IO EncryptedCipher
+genCipher config = do
+	random <- genrandom
+	encryptCipher config $ Cipher random
+	where
+		genrandom = gpgPipeRead
+			[ Params "--armor --gen-random"
+			, Param $ show randomquality
+			, Param $ show ciphersize
+			]
+		randomquality = 1 -- 1 is /dev/urandom; 2 is /dev/random
+		ciphersize = 1024
+
+{- Updates an existing Cipher, re-encrypting it as specified in the
+ - remote's configuration  -}
+updateCipher :: RemoteConfig -> EncryptedCipher -> IO EncryptedCipher
+updateCipher config encipher = do
+	cipher <- decryptCipher config encipher
+	encryptCipher config cipher
+
+{- Stores an EncryptedCipher in a remote's configuration. -}
+storeCipher :: RemoteConfig -> EncryptedCipher -> RemoteConfig
+storeCipher config (EncryptedCipher c) = M.insert "cipher" c config
+
+{- Extracts an EncryptedCipher from a remote's configuration. -}
+extractCipher :: RemoteConfig -> EncryptedCipher
+extractCipher config = case M.lookup "cipher" config of
+	Just c -> EncryptedCipher c
+	Nothing -> error "missing cipher in remote config"
+
+{- Encryptes a Cipher as specified by a remote's configuration. -}
+encryptCipher :: RemoteConfig -> Cipher -> IO EncryptedCipher
+encryptCipher config (Cipher c) = do
+	encipher <- gpgPipeBoth (encrypt++recipient) c
+	return $ EncryptedCipher encipher
+	where
+		encrypt =
+			[ Params "--encrypt --armor"
+			, Params "--trust-model always"
+			]
+		recipient = case M.lookup "encryption" config of
+			Nothing -> [ Param "--default-recipient-self" ]
+			Just r ->
+				-- Force gpg to only encrypt to the specified
+				-- recipients, not configured defaults.
+				[ Params "--no-encrypt-to --no-default-recipient"
+				, Param "--recipient"
+				, Param r
+				]
+
+{- Decrypting an EncryptedCipher is expensive; the Cipher should be cached. -}
+decryptCipher :: RemoteConfig -> EncryptedCipher -> IO Cipher
+decryptCipher = error "TODO"
+
+{- Genetates an encrypted form of a Key. The enctyption does not need to be
+ - reversable, nor does it need to be the same type of encryption used
+ - on content. -}
+encryptKey :: Cipher -> Key -> IO Key
+encryptKey = error "TODO"
+
+{- Streams content, encrypting. -}
+encryptContent :: Cipher -> L.ByteString -> IO L.ByteString
+encryptContent = error "TODO"
+
+{- Streams encrypted content, decrypting. -}
+decryptContent :: Cipher -> L.ByteString -> IO L.ByteString
+decryptContent = error "TODO"
+
+
+gpgParams :: [CommandParam] -> [String]
+gpgParams params = ["--batch", "--quiet"] ++ toCommand params
+
+gpgPipeRead :: [CommandParam] -> IO String
+gpgPipeRead params = pOpen ReadFromPipe "gpg" (gpgParams params) hGetContentsStrict
+
+gpgPipeBoth :: [CommandParam] -> String -> IO String
+gpgPipeBoth params input = do
+	(_, s) <- pipeBoth "gpg" (gpgParams params) input
+	return s