diff options
Diffstat (limited to 'Key.hs')
| -rw-r--r-- | Key.hs | 30 |
1 files changed, 13 insertions, 17 deletions
@@ -35,7 +35,7 @@ import qualified Utility.SimpleProtocol as Proto stubKey :: Key stubKey = Key { keyName = "" - , keyBackendName = "" + , keyVariety = OtherKey "" , keySize = Nothing , keyMtime = Nothing , keyChunkSize = Nothing @@ -69,8 +69,8 @@ fieldSep = '-' - The name field is always shown last, separated by doubled fieldSeps, - and is the only field allowed to contain the fieldSep. -} key2file :: Key -> FilePath -key2file Key { keyBackendName = b, keySize = s, keyMtime = m, keyChunkSize = cs, keyChunkNum = cn, keyName = n } = - b +++ ('s' ?: s) +++ ('m' ?: m) +++ ('S' ?: cs) +++ ('C' ?: cn) +++ (fieldSep : n) +key2file Key { keyVariety = kv, keySize = s, keyMtime = m, keyChunkSize = cs, keyChunkNum = cn, keyName = n } = + formatKeyVariety kv +++ ('s' ?: s) +++ ('m' ?: m) +++ ('S' ?: cs) +++ ('C' ?: cn) +++ (fieldSep : n) where "" +++ y = y x +++ "" = x @@ -80,12 +80,12 @@ key2file Key { keyBackendName = b, keySize = s, keyMtime = m, keyChunkSize = cs, file2key :: FilePath -> Maybe Key file2key s - | key == Just stubKey || (keyName <$> key) == Just "" || (keyBackendName <$> key) == Just "" = Nothing + | key == Just stubKey || (keyName <$> key) == Just "" || (keyVariety <$> key) == Just (OtherKey "") = Nothing | otherwise = key where key = startbackend stubKey s - startbackend k v = sepfield k v addbackend + startbackend k v = sepfield k v addvariety sepfield k v a = case span (/= fieldSep) v of (v', _:r) -> findfields r $ a k v' @@ -96,7 +96,7 @@ file2key s | otherwise = sepfield k v $ addfield c findfields _ v = v - addbackend k v = Just k { keyBackendName = v } + addvariety k v = Just k { keyVariety = parseKeyVariety v } -- This is a strict parser for security reasons; a key -- can contain only 4 fields, which all consist only of numbers. @@ -126,31 +126,27 @@ file2key s | validKeyName k v = Just $ k { keyName = v } | otherwise = Nothing -{- A key with a backend ending in "E" is an extension preserving key, - - using some hash. +{- When a key HasExt, the length of the extension is limited in order to + - mitigate against SHA1 collision attacks (specifically, chosen-prefix + - attacks). - - - The length of the extension is limited in order to mitigate against - - SHA1 collision attacks (specifically, chosen-prefix attacks). - In such an attack, the extension of the key could be made to contain - the collision generation data, with the result that a signed git commit - including such keys would not be secure. - - The maximum extension length ever generated for such a key was 8 - characters; 20 is used here to give a little future wiggle-room. - - The SHA1 common-prefix attack used 128 bytes of data. - - - - This code is here, and not in Backend.Hash (where it really belongs) - - so that file2key can check it whenever a Key is constructed. + - The SHA1 common-prefix attack needs 128 bytes of data. -} validKeyName :: Key -> String -> Bool -validKeyName k v - | end (keyBackendName k) == "E" = length (takeExtensions v) <= 20 +validKeyName k name + | hasExt (keyVariety k) = length (takeExtensions name) <= 20 | otherwise = True instance Arbitrary Key where arbitrary = Key <$> (listOf1 $ elements $ ['A'..'Z'] ++ ['a'..'z'] ++ ['0'..'9'] ++ "-_\r\n \t") - <*> (listOf1 $ elements ['A'..'Z']) -- BACKEND + <*> (parseKeyVariety <$> (listOf1 $ elements ['A'..'Z'])) -- BACKEND <*> ((abs <$>) <$> arbitrary) -- size cannot be negative <*> arbitrary <*> ((abs <$>) <$> arbitrary) -- chunksize cannot be negative |