1d263e1e7e
Some remotes like External need to run store and retrieve actions in Annex, not IO. In order to do that lift, I had to dive pretty deep into the utilities, making Utility.Gpg and Utility.Tmp be partly converted to using MonadIO, and Control.Monad.Catch for exception handling. There should be no behavior changes in this commit. This commit was sponsored by Michael Barabanov.
221 lines
7.8 KiB
Haskell
221 lines
7.8 KiB
Haskell
{- git-annex crypto
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-
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- Currently using gpg; could later be modified to support different
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- crypto backends if neccessary.
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-
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- Copyright 2011-2014 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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{-# LANGUAGE FlexibleInstances #-}
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{-# LANGUAGE Rank2Types #-}
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module Crypto (
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Cipher,
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KeyIds(..),
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EncKey,
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StorableCipher(..),
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genEncryptedCipher,
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genSharedCipher,
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updateEncryptedCipher,
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describeCipher,
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decryptCipher,
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encryptKey,
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feedFile,
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feedBytes,
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readBytes,
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encrypt,
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decrypt,
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getGpgEncParams,
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prop_HmacSha1WithCipher_sane
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) where
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import qualified Data.ByteString.Lazy as L
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import Data.ByteString.Lazy.UTF8 (fromString)
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import Control.Applicative
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import qualified Data.Map as M
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import Control.Monad.IO.Class
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import Control.Monad.Catch (MonadMask)
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import Common.Annex
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import qualified Utility.Gpg as Gpg
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import Types.Key
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import Types.Crypto
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import Types.Remote
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{- The beginning of a Cipher is used for MAC'ing; the remainder is used
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- as the GPG symmetric encryption passphrase when using the hybrid
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- scheme. Note that the cipher itself is base-64 encoded, hence the
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- string is longer than 'cipherSize': 683 characters, padded to 684.
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-
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- The 256 first characters that feed the MAC represent at best 192
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- bytes of entropy. However that's more than enough for both the
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- default MAC algorithm, namely HMAC-SHA1, and the "strongest"
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- currently supported, namely HMAC-SHA512, which respectively need
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- (ideally) 64 and 128 bytes of entropy.
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-
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- The remaining characters (320 bytes of entropy) is enough for GnuPG's
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- symetric cipher; unlike weaker public key crypto, the key does not
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- need to be too large.
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-}
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cipherBeginning :: Int
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cipherBeginning = 256
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cipherSize :: Int
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cipherSize = 512
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cipherPassphrase :: Cipher -> String
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cipherPassphrase (Cipher c) = drop cipherBeginning c
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cipherPassphrase (MacOnlyCipher _) = error "MAC-only cipher"
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cipherMac :: Cipher -> String
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cipherMac (Cipher c) = take cipherBeginning c
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cipherMac (MacOnlyCipher c) = c
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{- Creates a new Cipher, encrypted to the specified key id. -}
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genEncryptedCipher :: String -> EncryptedCipherVariant -> Bool -> IO StorableCipher
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genEncryptedCipher keyid variant highQuality = do
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ks <- Gpg.findPubKeys keyid
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random <- Gpg.genRandom highQuality size
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encryptCipher (mkCipher random) variant ks
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where
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(mkCipher, size) = case variant of
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Hybrid -> (Cipher, cipherSize) -- used for MAC + symmetric
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PubKey -> (MacOnlyCipher, cipherBeginning) -- only used for MAC
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{- Creates a new, shared Cipher. -}
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genSharedCipher :: Bool -> IO StorableCipher
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genSharedCipher highQuality =
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SharedCipher <$> Gpg.genRandom highQuality cipherSize
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{- Updates an existing Cipher, re-encrypting it to add or remove keyids,
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- depending on whether the first component is True or False. -}
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updateEncryptedCipher :: [(Bool, String)] -> StorableCipher -> IO StorableCipher
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updateEncryptedCipher _ SharedCipher{} = undefined
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updateEncryptedCipher [] encipher = return encipher
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updateEncryptedCipher newkeys encipher@(EncryptedCipher _ variant (KeyIds ks)) = do
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dropKeys <- listKeyIds [ k | (False, k) <- newkeys ]
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forM_ dropKeys $ \k -> unless (k `elem` ks) $
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error $ "Key " ++ k ++ " was not present; cannot remove."
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addKeys <- listKeyIds [ k | (True, k) <- newkeys ]
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let ks' = (addKeys ++ ks) \\ dropKeys
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when (null ks') $
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error "Cannot remove the last key."
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cipher <- decryptCipher encipher
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encryptCipher cipher variant $ KeyIds ks'
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where
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listKeyIds = concat <$$> mapM (keyIds <$$> Gpg.findPubKeys)
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describeCipher :: StorableCipher -> String
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describeCipher (SharedCipher _) = "shared cipher"
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describeCipher (EncryptedCipher _ variant (KeyIds ks)) =
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scheme ++ " with gpg " ++ keys ks ++ " " ++ unwords ks
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where
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scheme = case variant of
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Hybrid -> "hybrid cipher"
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PubKey -> "pubkey crypto"
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keys [_] = "key"
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keys _ = "keys"
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{- Encrypts a Cipher to the specified KeyIds. -}
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encryptCipher :: Cipher -> EncryptedCipherVariant -> KeyIds -> IO StorableCipher
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encryptCipher c variant (KeyIds ks) = do
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-- gpg complains about duplicate recipient keyids
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let ks' = nub $ sort ks
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let params = Gpg.pkEncTo ks' ++ Gpg.stdEncryptionParams False
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encipher <- Gpg.pipeStrict params cipher
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return $ EncryptedCipher encipher variant (KeyIds ks')
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where
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cipher = case c of
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Cipher x -> x
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MacOnlyCipher x -> x
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{- Decrypting an EncryptedCipher is expensive; the Cipher should be cached. -}
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decryptCipher :: StorableCipher -> IO Cipher
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decryptCipher (SharedCipher t) = return $ Cipher t
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decryptCipher (EncryptedCipher t variant _) =
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mkCipher <$> Gpg.pipeStrict [ Param "--decrypt" ] t
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where
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mkCipher = case variant of
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Hybrid -> Cipher
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PubKey -> MacOnlyCipher
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type EncKey = Key -> Key
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{- Generates an encrypted form of a Key. The encryption does not need to be
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- reversable, nor does it need to be the same type of encryption used
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- on content. It does need to be repeatable. -}
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encryptKey :: Mac -> Cipher -> EncKey
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encryptKey mac c k = stubKey
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{ keyName = macWithCipher mac c (key2file k)
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, keyBackendName = "GPG" ++ showMac mac
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}
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type Feeder = Handle -> IO ()
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type Reader m a = Handle -> m a
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feedFile :: FilePath -> Feeder
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feedFile f h = L.hPut h =<< L.readFile f
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feedBytes :: L.ByteString -> Feeder
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feedBytes = flip L.hPut
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readBytes :: (MonadIO m) => (L.ByteString -> m a) -> Reader m a
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readBytes a h = liftIO (L.hGetContents h) >>= a
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{- Runs a Feeder action, that generates content that is symmetrically
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- encrypted with the Cipher (unless it is empty, in which case
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- public-key encryption is used) using the given gpg options, and then
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- read by the Reader action. Note: For public-key encryption,
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- recipients MUST be included in 'params' (for instance using
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- 'getGpgEncParams'). -}
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encrypt :: (MonadIO m, MonadMask m) => [CommandParam] -> Cipher -> Feeder -> Reader m a -> m a
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encrypt params cipher = case cipher of
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Cipher{} -> Gpg.feedRead (params ++ Gpg.stdEncryptionParams True) $
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cipherPassphrase cipher
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MacOnlyCipher{} -> Gpg.pipeLazy $ params ++ Gpg.stdEncryptionParams False
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{- Runs a Feeder action, that generates content that is decrypted with the
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- Cipher (or using a private key if the Cipher is empty), and read by the
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- Reader action. -}
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decrypt :: (MonadIO m, MonadMask m) => Cipher -> Feeder -> Reader m a -> m a
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decrypt cipher = case cipher of
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Cipher{} -> Gpg.feedRead [Param "--decrypt"] $ cipherPassphrase cipher
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MacOnlyCipher{} -> Gpg.pipeLazy [Param "--decrypt"]
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macWithCipher :: Mac -> Cipher -> String -> String
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macWithCipher mac c = macWithCipher' mac (cipherMac c)
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macWithCipher' :: Mac -> String -> String -> String
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macWithCipher' mac c s = calcMac mac (fromString c) (fromString s)
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{- Ensure that macWithCipher' returns the same thing forevermore. -}
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prop_HmacSha1WithCipher_sane :: Bool
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prop_HmacSha1WithCipher_sane = known_good == macWithCipher' HmacSha1 "foo" "bar"
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where
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known_good = "46b4ec586117154dacd49d664e5d63fdc88efb51"
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{- Return some options suitable for GnuPG encryption, symmetric or not. -}
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class LensGpgEncParams a where getGpgEncParams :: a -> [CommandParam]
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{- Extract the GnuPG options from a pair of a Remote Config and a Remote
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- Git Config. -}
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instance LensGpgEncParams (RemoteConfig, RemoteGitConfig) where
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getGpgEncParams (c,gc) = map Param (remoteAnnexGnupgOptions gc) ++ getGpgEncParams c
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where
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{- Extract the GnuPG options from a Remote Config, ignoring any
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- git config settings. (Which is ok if the remote is just being set up
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- and so doesn't have any.)
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-
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- If the remote is configured to use public-key encryption,
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- look up the recipient keys and add them to the option list.-}
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instance LensGpgEncParams RemoteConfig where
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getGpgEncParams c = case M.lookup "encryption" c of
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Just "pubkey" -> Gpg.pkEncTo $ maybe [] (split ",") $ M.lookup "cipherkeys" c
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_ -> []
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{- Extract the GnuPG options from a Remote. -}
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instance LensGpgEncParams (RemoteA a) where
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getGpgEncParams r = getGpgEncParams (config r, gitconfig r)
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