-- | This is a wrapper around -- that currently does fingerprint generation and signature verification. -- -- The recommended way to import this module is: -- -- > import qualified Data.OpenPGP.Crypto as OpenPGP module Data.OpenPGP.Crypto (sign, verify, fingerprint) where import Numeric import Data.Word import Data.Bits import Data.Char import Data.List (find,foldl') import qualified Data.ByteString.Lazy as LZ import qualified Data.ByteString.Lazy.UTF8 as LZ (fromString) import Data.Binary import Codec.Utils (fromOctets) import qualified Codec.Encryption.RSA as RSA import qualified Data.Digest.MD5 as MD5 import qualified Data.Digest.SHA1 as SHA1 import qualified Data.Digest.SHA256 as SHA256 import qualified Data.Digest.SHA384 as SHA384 import qualified Data.Digest.SHA512 as SHA512 import qualified Data.OpenPGP as OpenPGP -- | Generate a key fingerprint from a PublicKeyPacket or SecretKeyPacket -- fingerprint :: OpenPGP.Packet -> String fingerprint p | OpenPGP.version p == 4 = map toUpper $ (`showHex` "") $ SHA1.toInteger $ SHA1.hash $ LZ.unpack (LZ.concat (OpenPGP.fingerprint_material p)) | OpenPGP.version p `elem` [2, 3] = map toUpper $ foldr (pad `oo` showHex) "" $ MD5.hash $ LZ.unpack (LZ.concat (OpenPGP.fingerprint_material p)) | otherwise = error "Unsupported Packet version or type in fingerprint" where oo = (.) . (.) pad s | odd $ length s = '0':s | otherwise = s find_key :: OpenPGP.Message -> String -> Maybe OpenPGP.Packet find_key = OpenPGP.find_key fingerprint keyfield_as_octets :: OpenPGP.Packet -> Char -> [Word8] keyfield_as_octets k f = LZ.unpack $ LZ.drop 2 (encode fld) where Just fld = lookup f (OpenPGP.key k) constTimeEq :: [Word8] -> [Word8] -> Bool constTimeEq xs ys | length xs /= length ys = False | otherwise = 0 == foldl' (\r (x,y) -> r .|. (x `xor` y)) 0 (zip xs ys) -- http://tools.ietf.org/html/rfc3447#page-43 emsa_pkcs1_v1_5_hash_padding :: OpenPGP.HashAlgorithm -> [Word8] emsa_pkcs1_v1_5_hash_padding OpenPGP.MD5 = [0x30, 0x20, 0x30, 0x0c, 0x06, 0x08, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, 0x05, 0x00, 0x04, 0x10] emsa_pkcs1_v1_5_hash_padding OpenPGP.SHA1 = [0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2b, 0x0e, 0x03, 0x02, 0x1a, 0x05, 0x00, 0x04, 0x14] emsa_pkcs1_v1_5_hash_padding OpenPGP.SHA256 = [0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05, 0x00, 0x04, 0x20] emsa_pkcs1_v1_5_hash_padding OpenPGP.SHA384 = [0x30, 0x41, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02, 0x05, 0x00, 0x04, 0x30] emsa_pkcs1_v1_5_hash_padding OpenPGP.SHA512 = [0x30, 0x51, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, 0x05, 0x00, 0x04, 0x40] emsa_pkcs1_v1_5_hash_padding _ = error "Unsupported HashAlgorithm in emsa_pkcs1_v1_5_hash_padding." hash :: OpenPGP.HashAlgorithm -> [Word8] -> [Word8] hash OpenPGP.MD5 = MD5.hash hash OpenPGP.SHA1 = drop 2 . LZ.unpack . encode . OpenPGP.MPI . SHA1.toInteger . SHA1.hash hash OpenPGP.SHA256 = SHA256.hash hash OpenPGP.SHA384 = SHA384.hash hash OpenPGP.SHA512 = SHA512.hash hash _ = error "Unsupported HashAlgorithm in hash." emsa_pkcs1_v1_5_encode :: [Word8] -> Int -> OpenPGP.HashAlgorithm -> [Word8] emsa_pkcs1_v1_5_encode m emLen algo = [0, 1] ++ replicate (emLen - length t - 3) 0xff ++ [0] ++ t where t = emsa_pkcs1_v1_5_hash_padding algo ++ hash algo m -- | Verify a message signature. Only supports RSA keys for now. verify :: OpenPGP.Message -- ^ Keys that may have made the signature -> OpenPGP.Message -- ^ LiteralData message to verify -> Int -- ^ Index of signature to verify (0th, 1st, etc) -> Bool verify keys message sigidx = encoded `constTimeEq` RSA.encrypt (n, e) raw_sig where raw_sig = LZ.unpack $ LZ.drop 2 $ encode (head $ OpenPGP.signature sig) encoded = emsa_pkcs1_v1_5_encode signature_over (length n) (OpenPGP.hash_algorithm sig) signature_over = LZ.unpack $ dta `LZ.append` OpenPGP.trailer sig (n, e) = (keyfield_as_octets k 'n', keyfield_as_octets k 'e') Just k = find_key keys issuer Just issuer = OpenPGP.signature_issuer sig sig = sigs !! sigidx (sigs, (OpenPGP.LiteralDataPacket {OpenPGP.content = dta}):_) = OpenPGP.signatures_and_data message -- | Sign data or key/userID pair. Only supports RSA keys for now. sign :: OpenPGP.Message -- ^ SecretKeys, one of which will be used -> OpenPGP.Message -- ^ Message containing data or key to sign, and optional signature packet -> OpenPGP.HashAlgorithm -- ^ HashAlgorithm to use in signature -> String -- ^ KeyID of key to choose or @[]@ for first -> Integer -- ^ Timestamp for signature (unless sig supplied) -> OpenPGP.Packet sign keys message hsh keyid timestamp = -- WARNING: this style of update is unsafe on most fields -- it is safe on signature and hash_head, though sig { OpenPGP.signature = [OpenPGP.MPI $ toNum final], OpenPGP.hash_head = toNum $ take 2 encoded } where -- toNum has explicit param so that it can remain polymorphic toNum l = fromOctets (256::Integer) l final = dropWhile (==0) $ RSA.decrypt (n, d) encoded encoded = emsa_pkcs1_v1_5_encode dta (length n) hsh (n, d) = (keyfield_as_octets k 'n', keyfield_as_octets k 'd') dta = LZ.unpack $ case signOver of { OpenPGP.LiteralDataPacket {OpenPGP.content = c} -> c; _ -> LZ.concat $ OpenPGP.fingerprint_material signOver ++ [ LZ.singleton 0xB4, encode (fromIntegral (length firstUserID) :: Word32), LZ.fromString firstUserID ] } `LZ.append` OpenPGP.trailer sig sig = findSigOrDefault (find OpenPGP.isSignaturePacket m) -- Either a SignaturePacket was found, or we need to make one findSigOrDefault (Just s) = OpenPGP.signaturePacket (OpenPGP.version s) (OpenPGP.signature_type s) OpenPGP.RSA -- force key and hash algorithm hsh (OpenPGP.hashed_subpackets s) (OpenPGP.unhashed_subpackets s) (OpenPGP.hash_head s) (OpenPGP.signature s) findSigOrDefault Nothing = OpenPGP.signaturePacket 4 defaultStype OpenPGP.RSA hsh ([ -- Do we really need to pass in timestamp just for the default? OpenPGP.SignatureCreationTimePacket $ fromIntegral timestamp, OpenPGP.IssuerPacket keyid' ] ++ (case signOver of OpenPGP.LiteralDataPacket {} -> [] _ -> [] -- TODO: OpenPGP.KeyFlagsPacket [0x01, 0x02] )) [] undefined undefined keyid' = reverse $ take 16 $ reverse $ fingerprint k Just k = find_key keys keyid Just (OpenPGP.UserIDPacket firstUserID) = find isUserID m defaultStype = case signOver of OpenPGP.LiteralDataPacket {OpenPGP.format = f} -> if f == 'b' then 0x00 else 0x01 _ -> 0x13 Just signOver = find isSignable m OpenPGP.Message m = message isSignable (OpenPGP.LiteralDataPacket {}) = True isSignable (OpenPGP.PublicKeyPacket {}) = True isSignable (OpenPGP.SecretKeyPacket {}) = True isSignable _ = False isUserID (OpenPGP.UserIDPacket {}) = True isUserID _ = False