{-# LANGUAGE OverloadedStrings #-}
module Codec.Encryption.OpenPGP.Internal (
countBits
, PktStreamContext(..)
, issuer
, emptyPSC
, pubkeyToMPIs
, multiplicativeInverse
, sigType
, sigPKA
, sigHA
, sigCT
, curveoidBSToCurve
, curveToCurveoidBS
, point2BS
) where
import Crypto.Number.Serialize (i2osp, os2ip)
import qualified Crypto.PubKey.DSA as DSA
import qualified Crypto.PubKey.ECC.ECDSA as ECDSA
import qualified Crypto.PubKey.ECC.Types as ECCT
import qualified Crypto.PubKey.RSA as RSA
import Data.Bits (testBit)
import qualified Data.ByteString as B
import Data.ByteString.Lazy (ByteString)
import qualified Data.ByteString.Lazy as BL
import Data.List (find)
import Data.Maybe (fromJust)
import Data.Word (Word8, Word16)
import Codec.Encryption.OpenPGP.Types
import Codec.Encryption.OpenPGP.Ontology (isIssuerSSP, isSigCreationTime)
countBits :: ByteString -> Word16
countBits bs
| BL.null bs = 0
| otherwise = fromIntegral (BL.length bs * 8) - fromIntegral (go (BL.head bs) 7)
where
go :: Word8 -> Int -> Word8
go _ 0 = 7
go n b = if testBit n b then 7 - fromIntegral b else go n (b-1)
data PktStreamContext = PktStreamContext { lastLD :: Pkt
, lastUIDorUAt :: Pkt
, lastSig :: Pkt
, lastPrimaryKey :: Pkt
, lastSubkey :: Pkt
}
emptyPSC :: PktStreamContext
emptyPSC = PktStreamContext (OtherPacketPkt 0 "lastLD placeholder") (OtherPacketPkt 0 "lastUIDorUAt placeholder") (OtherPacketPkt 0 "lastSig placeholder") (OtherPacketPkt 0 "lastPrimaryKey placeholder") (OtherPacketPkt 0 "lastSubkey placeholder")
issuer :: Pkt -> Maybe EightOctetKeyId
issuer (SignaturePkt (SigV4 _ _ _ _ usubs _ _)) = fmap (\(SigSubPacket _ (Issuer i)) -> i) (find isIssuerSSP usubs)
issuer _ = Nothing
pubkeyToMPIs :: PKey -> [MPI]
pubkeyToMPIs (RSAPubKey (RSA_PublicKey k)) = [MPI (RSA.public_n k), MPI (RSA.public_e k)]
pubkeyToMPIs (DSAPubKey (DSA_PublicKey k)) = [
pkParams DSA.params_p
, pkParams DSA.params_q
, pkParams DSA.params_g
, MPI . DSA.public_y $ k
]
where pkParams f = MPI . f . DSA.public_params $ k
pubkeyToMPIs (ElGamalPubKey p g y) = [MPI p, MPI g, MPI y]
pubkeyToMPIs (ECDHPubKey (ECDSA_PublicKey (ECDSA.PublicKey _ q)) _ _) = [MPI (os2ip (point2BS q))]
pubkeyToMPIs (ECDSAPubKey (ECDSA_PublicKey (ECDSA.PublicKey _ q))) = [MPI (os2ip (point2BS q))]
multiplicativeInverse :: Integral a => a -> a -> a
multiplicativeInverse _ 1 = 1
multiplicativeInverse q p = (n * q + 1) `div` p
where n = p - multiplicativeInverse p (q `mod` p)
sigType :: SignaturePayload -> Maybe SigType
sigType (SigV3 st _ _ _ _ _ _) = Just st
sigType (SigV4 st _ _ _ _ _ _) = Just st
sigType _ = Nothing
sigPKA :: SignaturePayload -> Maybe PubKeyAlgorithm
sigPKA (SigV3 _ _ _ pka _ _ _) = Just pka
sigPKA (SigV4 _ pka _ _ _ _ _) = Just pka
sigPKA _ = Nothing
sigHA :: SignaturePayload -> Maybe HashAlgorithm
sigHA (SigV3 _ _ _ _ ha _ _) = Just ha
sigHA (SigV4 _ _ ha _ _ _ _) = Just ha
sigHA _ = Nothing
sigCT :: SignaturePayload -> Maybe ThirtyTwoBitTimeStamp
sigCT (SigV3 _ ct _ _ _ _ _) = Just ct
sigCT (SigV4 _ _ _ hsubs _ _ _) = fmap (\(SigSubPacket _ (SigCreationTime i)) -> i) (find isSigCreationTime hsubs)
sigCT _ = Nothing
curveoidBSToCurve :: B.ByteString -> Either String ECCT.Curve
curveoidBSToCurve oidbs
| B.pack [0x2A,0x86,0x48,0xCE,0x3D,0x03,0x01,0x07] == oidbs = Right $ ECCT.getCurveByName ECCT.SEC_p256r1
| B.pack [0x2B,0x81,0x04,0x00,0x22] == oidbs = Right $ ECCT.getCurveByName ECCT.SEC_p384r1
| B.pack [0x2B,0x81,0x04,0x00,0x23] == oidbs = Right $ ECCT.getCurveByName ECCT.SEC_p521r1
| otherwise = Left "unknown curve OID"
curveToCurveoidBS :: ECCT.Curve -> Either String B.ByteString
curveToCurveoidBS curve
| curve == ECCT.getCurveByName ECCT.SEC_p256r1 = Right $ B.pack [0x2A,0x86,0x48,0xCE,0x3D,0x03,0x01,0x07]
| curve == ECCT.getCurveByName ECCT.SEC_p384r1 = Right $ B.pack [0x2B,0x81,0x04,0x00,0x22]
| curve == ECCT.getCurveByName ECCT.SEC_p521r1 = Right $ B.pack [0x2B,0x81,0x04,0x00,0x23]
| otherwise = Left "unknown curve"
point2BS :: ECCT.PublicPoint -> B.ByteString
point2BS (ECCT.Point x y) = B.concat [B.singleton 0x04, i2osp x, i2osp y]
point2BS ECCT.PointO = error "FIXME: point at infinity"