1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
|
{- git-annex crypto
-
- Currently using gpg; could later be modified to support different
- crypto backends if neccessary.
-
- Copyright 2011-2016 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE Rank2Types #-}
module Crypto (
Cipher,
KeyIds(..),
EncKey,
StorableCipher(..),
genEncryptedCipher,
genSharedCipher,
genSharedPubKeyCipher,
updateCipherKeyIds,
decryptCipher,
encryptKey,
isEncKey,
feedFile,
feedBytes,
readBytes,
encrypt,
decrypt,
LensGpgEncParams(..),
prop_HmacSha1WithCipher_sane
) where
import qualified Data.ByteString.Lazy as L
import Data.ByteString.UTF8 (fromString)
import qualified Data.Map as M
import Control.Monad.IO.Class
import Annex.Common
import qualified Utility.Gpg as Gpg
import Types.Crypto
import Types.Remote
{- The beginning of a Cipher is used for MAC'ing; the remainder is used
- as the GPG symmetric encryption passphrase when using the hybrid
- scheme. Note that the cipher itself is base-64 encoded, hence the
- string is longer than 'cipherSize': 683 characters, padded to 684.
-
- The 256 first characters that feed the MAC represent at best 192
- bytes of entropy. However that's more than enough for both the
- default MAC algorithm, namely HMAC-SHA1, and the "strongest"
- currently supported, namely HMAC-SHA512, which respectively need
- (ideally) 64 and 128 bytes of entropy.
-
- The remaining characters (320 bytes of entropy) is enough for GnuPG's
- symetric cipher; unlike weaker public key crypto, the key does not
- need to be too large.
-}
cipherBeginning :: Int
cipherBeginning = 256
cipherSize :: Int
cipherSize = 512
cipherPassphrase :: Cipher -> String
cipherPassphrase (Cipher c) = drop cipherBeginning c
cipherPassphrase (MacOnlyCipher _) = error "MAC-only cipher"
cipherMac :: Cipher -> String
cipherMac (Cipher c) = take cipherBeginning c
cipherMac (MacOnlyCipher c) = c
{- Creates a new Cipher, encrypted to the specified key id. -}
genEncryptedCipher :: LensGpgEncParams c => Gpg.GpgCmd -> c -> Gpg.KeyId -> EncryptedCipherVariant -> Bool -> IO StorableCipher
genEncryptedCipher cmd c keyid variant highQuality = do
ks <- Gpg.findPubKeys cmd keyid
random <- Gpg.genRandom cmd highQuality size
encryptCipher cmd c (mkCipher random) variant ks
where
(mkCipher, size) = case variant of
Hybrid -> (Cipher, cipherSize) -- used for MAC + symmetric
PubKey -> (MacOnlyCipher, cipherBeginning) -- only used for MAC
{- Creates a new, shared Cipher. -}
genSharedCipher :: Gpg.GpgCmd -> Bool -> IO StorableCipher
genSharedCipher cmd highQuality =
SharedCipher <$> Gpg.genRandom cmd highQuality cipherSize
{- Creates a new, shared Cipher, and looks up the gpg public key that will
- be used for encrypting content. -}
genSharedPubKeyCipher :: Gpg.GpgCmd -> Gpg.KeyId -> Bool -> IO StorableCipher
genSharedPubKeyCipher cmd keyid highQuality = do
ks <- Gpg.findPubKeys cmd keyid
random <- Gpg.genRandom cmd highQuality cipherSize
return $ SharedPubKeyCipher random ks
{- Updates an existing Cipher, making changes to its keyids.
-
- When the Cipher is encrypted, re-encrypts it. -}
updateCipherKeyIds :: LensGpgEncParams encparams => Gpg.GpgCmd -> encparams -> [(Bool, Gpg.KeyId)] -> StorableCipher -> IO StorableCipher
updateCipherKeyIds _ _ _ SharedCipher{} = error "Cannot update shared cipher"
updateCipherKeyIds _ _ [] c = return c
updateCipherKeyIds cmd encparams changes encipher@(EncryptedCipher _ variant ks) = do
ks' <- updateCipherKeyIds' cmd changes ks
cipher <- decryptCipher cmd encparams encipher
encryptCipher cmd encparams cipher variant ks'
updateCipherKeyIds cmd _ changes (SharedPubKeyCipher cipher ks) =
SharedPubKeyCipher cipher <$> updateCipherKeyIds' cmd changes ks
updateCipherKeyIds' :: Gpg.GpgCmd -> [(Bool, Gpg.KeyId)] -> KeyIds -> IO KeyIds
updateCipherKeyIds' cmd changes (KeyIds ks) = do
dropkeys <- listKeyIds [ k | (False, k) <- changes ]
forM_ dropkeys $ \k -> unless (k `elem` ks) $
error $ "Key " ++ k ++ " was not present; cannot remove."
addkeys <- listKeyIds [ k | (True, k) <- changes ]
let ks' = (addkeys ++ ks) \\ dropkeys
when (null ks') $
error "Cannot remove the last key."
return $ KeyIds ks'
where
listKeyIds = concat <$$> mapM (keyIds <$$> Gpg.findPubKeys cmd)
{- Encrypts a Cipher to the specified KeyIds. -}
encryptCipher :: LensGpgEncParams c => Gpg.GpgCmd -> c -> Cipher -> EncryptedCipherVariant -> KeyIds -> IO StorableCipher
encryptCipher cmd c cip variant (KeyIds ks) = do
-- gpg complains about duplicate recipient keyids
let ks' = nub $ sort ks
let params = concat
[ getGpgEncParamsBase c
, Gpg.pkEncTo ks'
, Gpg.stdEncryptionParams False
]
encipher <- Gpg.pipeStrict cmd params cipher
return $ EncryptedCipher encipher variant (KeyIds ks')
where
cipher = case cip of
Cipher x -> x
MacOnlyCipher x -> x
{- Decrypting an EncryptedCipher is expensive; the Cipher should be cached. -}
decryptCipher :: LensGpgEncParams c => Gpg.GpgCmd -> c -> StorableCipher -> IO Cipher
decryptCipher _ _ (SharedCipher t) = return $ Cipher t
decryptCipher _ _ (SharedPubKeyCipher t _) = return $ MacOnlyCipher t
decryptCipher cmd c (EncryptedCipher t variant _) =
mkCipher <$> Gpg.pipeStrict cmd params t
where
mkCipher = case variant of
Hybrid -> Cipher
PubKey -> MacOnlyCipher
params = Param "--decrypt" : getGpgDecParams c
type EncKey = Key -> Key
{- Generates an encrypted form of a Key. The encryption does not need to be
- reversable, nor does it need to be the same type of encryption used
- on content. It does need to be repeatable. -}
encryptKey :: Mac -> Cipher -> EncKey
encryptKey mac c k = stubKey
{ keyName = macWithCipher mac c (key2file k)
, keyBackendName = encryptedBackendNamePrefix ++ showMac mac
}
encryptedBackendNamePrefix :: String
encryptedBackendNamePrefix = "GPG"
isEncKey :: Key -> Bool
isEncKey k = encryptedBackendNamePrefix `isPrefixOf` keyBackendName k
type Feeder = Handle -> IO ()
type Reader m a = Handle -> m a
feedFile :: FilePath -> Feeder
feedFile f h = L.hPut h =<< L.readFile f
feedBytes :: L.ByteString -> Feeder
feedBytes = flip L.hPut
readBytes :: (MonadIO m) => (L.ByteString -> m a) -> Reader m a
readBytes a h = liftIO (L.hGetContents h) >>= a
{- Runs a Feeder action, that generates content that is symmetrically
- encrypted with the Cipher (unless it is empty, in which case
- public-key encryption is used) using the given gpg options, and then
- read by the Reader action. -}
encrypt :: (MonadIO m, MonadMask m, LensGpgEncParams c) => Gpg.GpgCmd -> c -> Cipher -> Feeder -> Reader m a -> m a
encrypt cmd c cipher = case cipher of
Cipher{} -> Gpg.feedRead cmd (params ++ Gpg.stdEncryptionParams True) $
cipherPassphrase cipher
MacOnlyCipher{} -> Gpg.pipeLazy cmd $ params ++ Gpg.stdEncryptionParams False
where
params = getGpgEncParams c
{- Runs a Feeder action, that generates content that is decrypted with the
- Cipher (or using a private key if the Cipher is empty), and read by the
- Reader action. -}
decrypt :: (MonadIO m, MonadMask m, LensGpgEncParams c) => Gpg.GpgCmd -> c -> Cipher -> Feeder -> Reader m a -> m a
decrypt cmd c cipher = case cipher of
Cipher{} -> Gpg.feedRead cmd params $ cipherPassphrase cipher
MacOnlyCipher{} -> Gpg.pipeLazy cmd params
where
params = Param "--decrypt" : getGpgDecParams c
macWithCipher :: Mac -> Cipher -> String -> String
macWithCipher mac c = macWithCipher' mac (cipherMac c)
macWithCipher' :: Mac -> String -> String -> String
macWithCipher' mac c s = calcMac mac (fromString c) (fromString s)
{- Ensure that macWithCipher' returns the same thing forevermore. -}
prop_HmacSha1WithCipher_sane :: Bool
prop_HmacSha1WithCipher_sane = known_good == macWithCipher' HmacSha1 "foo" "bar"
where
known_good = "46b4ec586117154dacd49d664e5d63fdc88efb51"
class LensGpgEncParams a where
{- Base parameters for encrypting. Does not include specification
- of recipient keys. -}
getGpgEncParamsBase :: a -> [CommandParam]
{- Parameters for encrypting. When the remote is configured to use
- public-key encryption, includes specification of recipient keys. -}
getGpgEncParams :: a -> [CommandParam]
{- Parameters for decrypting. -}
getGpgDecParams :: a -> [CommandParam]
{- Extract the GnuPG options from a pair of a Remote Config and a Remote
- Git Config. -}
instance LensGpgEncParams (RemoteConfig, RemoteGitConfig) where
getGpgEncParamsBase (_c,gc) = map Param (remoteAnnexGnupgOptions gc)
getGpgEncParams (c,gc) = getGpgEncParamsBase (c,gc) ++
{- When the remote is configured to use public-key encryption,
- look up the recipient keys and add them to the option list. -}
case M.lookup "encryption" c of
Just "pubkey" -> Gpg.pkEncTo $ maybe [] (split ",") $ M.lookup "cipherkeys" c
Just "sharedpubkey" -> Gpg.pkEncTo $ maybe [] (split ",") $ M.lookup "pubkeys" c
_ -> []
getGpgDecParams (_c,gc) = map Param (remoteAnnexGnupgDecryptOptions gc)
{- Extract the GnuPG options from a Remote. -}
instance LensGpgEncParams (RemoteA a) where
getGpgEncParamsBase r = getGpgEncParamsBase (config r, gitconfig r)
getGpgEncParams r = getGpgEncParams (config r, gitconfig r)
getGpgDecParams r = getGpgDecParams (config r, gitconfig r)
|
