{-# LANGUAGE CPP #-}
module Codec.Encryption.OpenPGP.Signatures (
verifySigWith
, verifyAgainstKeyring
, verifyAgainstKeys
, verifyTKWith
) where
#if !MIN_VERSION_base(4,8,0)
import Control.Applicative ((<$>), (<*>))
#endif
import Control.Error.Util (hush)
import Control.Lens ((^.), _1)
import Control.Monad (liftM2)
import qualified Crypto.Hash.Algorithms as CHA
import Crypto.Number.Serialize (i2osp)
import qualified Crypto.PubKey.DSA as DSA
import qualified Crypto.PubKey.RSA.PKCS15 as P15
import Data.ByteString.Lazy (ByteString)
import qualified Data.ByteString.Lazy as BL
import Data.Either (lefts, rights)
import Data.IxSet.Typed ((@=))
import qualified Data.IxSet.Typed as IxSet
import Data.List.NonEmpty (NonEmpty(..))
import Data.Text (Text)
import Data.Time.Clock (UTCTime(..), diffUTCTime)
import Data.Time.Clock.POSIX (posixSecondsToUTCTime)
import Data.Binary.Put (runPut)
import Codec.Encryption.OpenPGP.Fingerprint (eightOctetKeyID, fingerprint)
import Codec.Encryption.OpenPGP.Internal (PktStreamContext(..), issuer, emptyPSC, truncatingVerify)
import Codec.Encryption.OpenPGP.Ontology (isRevokerP, isRevocationKeySSP, isSubkeyBindingSig, isSubkeyRevocation)
import Codec.Encryption.OpenPGP.SerializeForSigs (putPartialSigforSigning, putSigTrailer, payloadForSig)
import Codec.Encryption.OpenPGP.Types
import Data.Conduit.OpenPGP.Keyring.Instances ()
verifySigWith :: (Pkt -> Maybe UTCTime -> ByteString -> Either String Verification) -> Pkt -> PktStreamContext -> Maybe UTCTime -> Either String Verification
verifySigWith vf sig@(SignaturePkt (SigV4 st _ _ hs _ _ _)) state mt = do
v <- vf sig mt (payloadForSig st state)
_ <- mapM_ (checkIssuer (eightOctetKeyID (v^.verificationSigner)) . _sspPayload) hs
return v
where
checkIssuer :: Either String EightOctetKeyId -> SigSubPacketPayload -> Either String Bool
checkIssuer (Right signer) (Issuer i) = if signer == i then Right True else Left "issuer subpacket does not match"
checkIssuer (Left err) (Issuer _) = Left $ "issuer subpacket cannot be checked (" ++ err ++ ")"
checkIssuer _ _ = Right True
verifySigWith _ _ _ _ = Left "This should never happen (verifySigWith)."
verifyTKWith :: (Pkt -> PktStreamContext -> Maybe UTCTime -> Either String Verification) -> Maybe UTCTime -> TK -> Either String TK
verifyTKWith vsf mt key = do
revokers <- checkRevokers key
revs <- checkKeyRevocations revokers key
let uids = filter (\(_, sps) -> sps /= []) . checkUidSigs $ key^.tkUIDs
let uats = filter (\(_, sps) -> sps /= []) . checkUAtSigs $ key^.tkUAts
let subs = concatMap checkSub $ key^.tkSubs
return (TK (key^.tkKey) revs uids uats subs)
where
checkRevokers = Right . concat . rights . map verifyRevoker . filter isRevokerP . _tkRevs
checkKeyRevocations :: [(PubKeyAlgorithm, TwentyOctetFingerprint)] -> TK -> Either String [SignaturePayload]
checkKeyRevocations rs k = Prelude.sequence . concatMap (filterRevs rs) . rights . map (liftM2 fmap (,) vSig) $ k^.tkRevs
checkUidSigs :: [(Text, [SignaturePayload])] -> [(Text, [SignaturePayload])]
checkUidSigs = map (\(uid, sps) -> (uid, (rights . map (\sp -> fmap (const sp) (vUid (uid, sp)))) sps))
checkUAtSigs :: [([UserAttrSubPacket], [SignaturePayload])] -> [([UserAttrSubPacket], [SignaturePayload])]
checkUAtSigs = map (\(uat, sps) -> (uat, (rights . map (\sp -> fmap (const sp) (vUAt (uat, sp)))) sps))
checkSub :: (Pkt, [SignaturePayload]) -> [(Pkt, [SignaturePayload])]
checkSub (pkt, sps) = if revokedSub pkt sps then [] else checkSub' pkt sps
revokedSub :: Pkt -> [SignaturePayload] -> Bool
revokedSub _ [] = False
revokedSub p sigs = any (vSubSig p) (filter isSubkeyRevocation sigs)
checkSub' :: Pkt -> [SignaturePayload] -> [(Pkt, [SignaturePayload])]
checkSub' p sps = let goodsigs = filter (vSubSig p) (filter isSubkeyBindingSig sps) in if null goodsigs then [] else [(p, goodsigs)]
getHasheds (SigV4 _ _ _ ha _ _ _) = ha
getHasheds _ = []
filterRevs :: [(PubKeyAlgorithm, TwentyOctetFingerprint)] -> (SignaturePayload, Verification) -> [Either String SignaturePayload]
filterRevs vokers spv = case spv of
(s@(SigV4 SignatureDirectlyOnAKey _ _ _ _ _ _), _) -> [Right s]
(s@(SigV4 KeyRevocationSig pka _ _ _ _ _), v) -> if (v^.verificationSigner == key ^. tkKey._1) || any (\(p,f) -> p == pka && f == fingerprint (v^.verificationSigner)) vokers then [Left "Key revoked"] else [Right s]
_ -> []
vUid :: (Text, SignaturePayload) -> Either String Verification
vUid (uid, sp) = vsf (SignaturePkt sp) emptyPSC { lastPrimaryKey = PublicKeyPkt (key ^. tkKey._1), lastUIDorUAt = UserIdPkt uid } mt
vUAt :: ([UserAttrSubPacket], SignaturePayload) -> Either String Verification
vUAt (uat, sp) = vsf (SignaturePkt sp) emptyPSC { lastPrimaryKey = PublicKeyPkt (key ^. tkKey._1), lastUIDorUAt = UserAttributePkt uat } mt
vSig :: SignaturePayload -> Either String Verification
vSig sp = vsf (SignaturePkt sp) emptyPSC { lastPrimaryKey = PublicKeyPkt (key ^. tkKey._1) } mt
vSubSig :: Pkt -> SignaturePayload -> Bool
vSubSig sk sp = case vsf (SignaturePkt sp) emptyPSC { lastPrimaryKey = PublicKeyPkt (key ^. tkKey._1), lastSubkey = sk} mt of
Left _ -> False
Right _ -> True
verifyRevoker :: SignaturePayload -> Either String [(PubKeyAlgorithm, TwentyOctetFingerprint)]
verifyRevoker sp = do
_ <- vSig sp
return (map (\(SigSubPacket _ (RevocationKey _ pka fp)) -> (pka, fp)) . filter isRevocationKeySSP $ getHasheds sp)
verifyAgainstKeyring :: Keyring -> Pkt -> Maybe UTCTime -> ByteString -> Either String Verification
verifyAgainstKeyring kr sig mt payload = do
i <- maybe (Left "issuer not found") Right (issuer sig)
potentialmatches <- if IxSet.null (kr @= i) then Left "pubkey not found" else Right (kr @= i)
verifyAgainstKeys (IxSet.toList potentialmatches) sig mt payload
verifyAgainstKeys :: [TK] -> Pkt -> Maybe UTCTime -> ByteString -> Either String Verification
verifyAgainstKeys ks sig mt payload = do
let allrelevantpkps = filter (\x -> ((==) <$> issuer sig <*> hush (eightOctetKeyID x)) == Just True) (concatMap (\x -> (x ^. tkKey._1):map subPKP (_tkSubs x)) ks)
let results = map (\pkp -> verify' sig pkp (hashalgo sig) (BL.toStrict (finalPayload sig payload))) allrelevantpkps
case rights results of
[] -> Left (concatMap (++"/") (lefts results))
[r] -> do _ <- isSignatureExpired sig mt
return (Verification r ((_signaturePayload . fromPkt) sig))
_ -> Left "multiple successes; unexpected condition"
where
subPKP (pack, _) = subPKP' pack
subPKP' (PublicSubkeyPkt p) = p
subPKP' (SecretSubkeyPkt p _) = p
subPKP' _ = error "This should never happen (subPKP')"
verify' (SignaturePkt s) (pub@(PKPayload V4 _ _ _ pkey)) SHA1 pl = verify'' (pkaAndMPIs s) CHA.SHA1 pub pkey pl
verify' (SignaturePkt s) (pub@(PKPayload V4 _ _ _ pkey)) RIPEMD160 pl = verify'' (pkaAndMPIs s) CHA.RIPEMD160 pub pkey pl
verify' (SignaturePkt s) (pub@(PKPayload V4 _ _ _ pkey)) SHA256 pl = verify'' (pkaAndMPIs s) CHA.SHA256 pub pkey pl
verify' (SignaturePkt s) (pub@(PKPayload V4 _ _ _ pkey)) SHA384 pl = verify'' (pkaAndMPIs s) CHA.SHA384 pub pkey pl
verify' (SignaturePkt s) (pub@(PKPayload V4 _ _ _ pkey)) SHA512 pl = verify'' (pkaAndMPIs s) CHA.SHA512 pub pkey pl
verify' (SignaturePkt s) (pub@(PKPayload V4 _ _ _ pkey)) SHA224 pl = verify'' (pkaAndMPIs s) CHA.SHA224 pub pkey pl
verify' (SignaturePkt s) (pub@(PKPayload V4 _ _ _ pkey)) DeprecatedMD5 pl = verify'' (pkaAndMPIs s) CHA.MD5 pub pkey pl
verify' _ _ _ _ = error "This should never happen (verify')."
verify'' (DSA,mpis) hd pub (DSAPubKey (DSA_PublicKey pkey)) bs = verify''' (dsaVerify mpis hd pkey bs) pub
verify'' (RSA,mpis) hd pub (RSAPubKey (RSA_PublicKey pkey)) bs = verify''' (rsaVerify mpis hd pkey bs) pub
verify'' _ _ _ _ _ = Left "unimplemented key type"
verify''' f pub = if f then Right pub else Left "verification failed"
dsaVerify (r:|[s]) hd pkey = truncatingVerify hd pkey (dsaMPIsToSig r s)
dsaVerify _ _ _ = const False
rsaVerify mpis hd pkey bs = P15.verify (Just hd) pkey bs (rsaMPItoSig mpis)
dsaMPIsToSig r s = DSA.Signature (unMPI r) (unMPI s)
rsaMPItoSig (s:|[]) = i2osp (unMPI s)
hashalgo :: Pkt -> HashAlgorithm
hashalgo (SignaturePkt (SigV4 _ _ ha _ _ _ _)) = ha
hashalgo _ = error "This should never happen (hashalgo)."
pkaAndMPIs (SigV4 _ pka _ _ _ _ mpis) = (pka,mpis)
pkaAndMPIs _ = error "This should never happen (pkaAndMPIs)."
isSignatureExpired :: Pkt -> Maybe UTCTime -> Either String Bool
isSignatureExpired _ Nothing = return False
isSignatureExpired s (Just t) = if any (expiredBefore t) ((\(SigV4 _ _ _ h _ _ _) -> h) . _signaturePayload . fromPkt $ s) then Left "signature expired" else return True
expiredBefore :: UTCTime -> SigSubPacket -> Bool
expiredBefore ct (SigSubPacket _ (SigExpirationTime et)) = fromEnum ((posixSecondsToUTCTime . toEnum . fromEnum) et `diffUTCTime` ct) < 0
expiredBefore _ _ = False
finalPayload :: Pkt -> ByteString -> ByteString
finalPayload s pl = BL.concat [pl, sigbit, trailer s]
where
sigbit = runPut $ putPartialSigforSigning s
trailer :: Pkt -> ByteString
trailer (SignaturePkt SigV4{}) = runPut $ putSigTrailer s
trailer _ = BL.empty