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|
{- common functions for encryptable remotes
-
- Copyright 2011 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Remote.Helper.Encryptable (
EncryptionIsSetup,
encryptionSetup,
noEncryptionUsed,
encryptionAlreadySetup,
remoteCipher,
remoteCipher',
embedCreds,
cipherKey,
storeCipher,
extractCipher,
describeEncryption,
) where
import qualified Data.Map as M
import qualified "sandi" Codec.Binary.Base64 as B64
import qualified Data.ByteString as B
import Data.Bits.Utils
import Common.Annex
import Types.Remote
import Crypto
import Types.Crypto
import qualified Annex
-- Used to ensure that encryption has been set up before trying to
-- eg, store creds in the remote config that would need to use the
-- encryption setup.
data EncryptionIsSetup = EncryptionIsSetup | NoEncryption
-- Remotes that don't use encryption can use this instead of
-- encryptionSetup.
noEncryptionUsed :: EncryptionIsSetup
noEncryptionUsed = NoEncryption
-- Using this avoids the type-safe check, so you'd better be sure
-- of what you're doing.
encryptionAlreadySetup :: EncryptionIsSetup
encryptionAlreadySetup = EncryptionIsSetup
{- Encryption setup for a remote. The user must specify whether to use
- an encryption key, or not encrypt. An encrypted cipher is created, or is
- updated to be accessible to an additional encryption key. Or the user
- could opt to use a shared cipher, which is stored unencrypted. -}
encryptionSetup :: RemoteConfig -> Annex (RemoteConfig, EncryptionIsSetup)
encryptionSetup c = maybe genCipher updateCipher $ extractCipher c
where
-- The type of encryption
encryption = M.lookup "encryption" c
-- Generate a new cipher, depending on the chosen encryption scheme
genCipher = case encryption of
_ | M.member "cipher" c || M.member "cipherkeys" c -> cannotchange
Just "none" -> return (c, NoEncryption)
Just "shared" -> use "encryption setup" . genSharedCipher
=<< highRandomQuality
-- hybrid encryption is the default when a keyid is
-- specified but no encryption
_ | maybe (M.member "keyid" c) (== "hybrid") encryption ->
use "encryption setup" . genEncryptedCipher key Hybrid
=<< highRandomQuality
Just "pubkey" -> use "encryption setup" . genEncryptedCipher key PubKey
=<< highRandomQuality
_ -> error $ "Specify " ++ intercalate " or "
(map ("encryption=" ++)
["none","shared","hybrid","pubkey"])
++ "."
key = fromMaybe (error "Specifiy keyid=...") $ M.lookup "keyid" c
newkeys = maybe [] (\k -> [(True,k)]) (M.lookup "keyid+" c) ++
maybe [] (\k -> [(False,k)]) (M.lookup "keyid-" c)
cannotchange = error "Cannot set encryption type of existing remotes."
-- Update an existing cipher if possible.
updateCipher v = case v of
SharedCipher _ | maybe True (== "shared") encryption -> return (c', EncryptionIsSetup)
EncryptedCipher _ variant _
| maybe True (== if variant == Hybrid then "hybrid" else "pubkey") encryption ->
use "encryption update" $ updateEncryptedCipher newkeys v
_ -> cannotchange
use m a = do
showNote m
cipher <- liftIO a
showNote $ describeCipher cipher
return (storeCipher c' cipher, EncryptionIsSetup)
highRandomQuality =
(&&) (maybe True ( /= "false") $ M.lookup "highRandomQuality" c)
<$> fmap not (Annex.getState Annex.fast)
c' = foldr M.delete c
-- git-annex used to remove 'encryption' as well, since
-- it was redundant; we now need to keep it for
-- public-key encryption, hence we leave it on newer
-- remotes (while being backward-compatible).
[ "keyid", "keyid+", "keyid-", "highRandomQuality" ]
remoteCipher :: RemoteConfig -> Annex (Maybe Cipher)
remoteCipher = fmap fst <$$> remoteCipher'
{- Gets encryption Cipher. The decrypted Ciphers are cached in the Annex
- state. -}
remoteCipher' :: RemoteConfig -> Annex (Maybe (Cipher, StorableCipher))
remoteCipher' c = go $ extractCipher c
where
go Nothing = return Nothing
go (Just encipher) = do
cache <- Annex.getState Annex.ciphers
case M.lookup encipher cache of
Just cipher -> return $ Just (cipher, encipher)
Nothing -> do
cipher <- liftIO $ decryptCipher encipher
Annex.changeState (\s -> s { Annex.ciphers = M.insert encipher cipher cache })
return $ Just (cipher, encipher)
{- Checks if the remote's config allows storing creds in the remote's config.
-
- embedcreds=yes allows this, and embedcreds=no prevents it.
-
- If not set, the default is to only store creds when it's surely safe:
- When gpg encryption is used, in which case the creds will be encrypted
- using it. Not when a shared cipher is used.
-}
embedCreds :: RemoteConfig -> Bool
embedCreds c
| M.lookup "embedcreds" c == Just "yes" = True
| M.lookup "embedcreds" c == Just "no" = False
| isJust (M.lookup "cipherkeys" c) && isJust (M.lookup "cipher" c) = True
| otherwise = False
{- Gets encryption Cipher, and key encryptor. -}
cipherKey :: RemoteConfig -> Annex (Maybe (Cipher, EncKey))
cipherKey c = fmap make <$> remoteCipher c
where
make ciphertext = (ciphertext, encryptKey mac ciphertext)
mac = fromMaybe defaultMac $ M.lookup "mac" c >>= readMac
{- Stores an StorableCipher in a remote's configuration. -}
storeCipher :: RemoteConfig -> StorableCipher -> RemoteConfig
storeCipher c (SharedCipher t) = M.insert "cipher" (toB64bs t) c
storeCipher c (EncryptedCipher t _ ks) =
M.insert "cipher" (toB64bs t) $ M.insert "cipherkeys" (showkeys ks) c
where
showkeys (KeyIds l) = intercalate "," l
{- Extracts an StorableCipher from a remote's configuration. -}
extractCipher :: RemoteConfig -> Maybe StorableCipher
extractCipher c = case (M.lookup "cipher" c,
M.lookup "cipherkeys" c,
M.lookup "encryption" c) of
(Just t, Just ks, encryption) | maybe True (== "hybrid") encryption ->
Just $ EncryptedCipher (fromB64bs t) Hybrid (readkeys ks)
(Just t, Just ks, Just "pubkey") ->
Just $ EncryptedCipher (fromB64bs t) PubKey (readkeys ks)
(Just t, Nothing, encryption) | maybe True (== "shared") encryption ->
Just $ SharedCipher (fromB64bs t)
_ -> Nothing
where
readkeys = KeyIds . split ","
describeEncryption :: RemoteConfig -> String
describeEncryption c = case extractCipher c of
Nothing -> "not encrypted"
(Just (SharedCipher _)) -> "encrypted (encryption key stored in git repository)"
(Just (EncryptedCipher _ v (KeyIds { keyIds = ks }))) -> unwords $ catMaybes
[ Just "encrypted (to gpg keys:"
, Just (unwords ks ++ ")")
, case v of
PubKey -> Nothing
Hybrid -> Just "(hybrid mode)"
]
{- Not using Utility.Base64 because these "Strings" are really
- bags of bytes and that would convert to unicode and not round-trip
- cleanly. -}
toB64bs :: String -> String
toB64bs = w82s . B.unpack . B64.encode . B.pack . s2w8
fromB64bs :: String -> String
fromB64bs s = either (const bad) (w82s . B.unpack) (B64.decode $ B.pack $ s2w8 s)
where
bad = error "bad base64 encoded data"
|
