-- |
-- Module : Data.X509.Validation.Signature
-- License : BSD-style
-- Maintainer : Vincent Hanquez <vincent@snarc.org>
-- Stability : experimental
-- Portability : unknown
--
-- X.509 Certificate and CRL signature verification
module Data.X509.Validation.Signature (
verifySignedSignature,
verifySignature,
SignatureVerification (..),
SignatureFailure (..),
) where
import Crypto.Error (CryptoFailable (..))
import Crypto.Hash
import qualified Crypto.PubKey.DSA as DSA
import qualified Crypto.PubKey.ECC.ECDSA as ECDSA
import qualified Crypto.PubKey.ECC.Types as ECC
import qualified Crypto.PubKey.Ed25519 as Ed25519
import qualified Crypto.PubKey.Ed448 as Ed448
import qualified Crypto.PubKey.RSA.PKCS15 as RSA
import qualified Crypto.PubKey.RSA.PSS as PSS
import Data.ASN1.BinaryEncoding
import Data.ASN1.Encoding
import Data.ASN1.Types
import Data.ByteString (ByteString)
import Data.X509
import Data.X509.EC
-- | A set of possible return from signature verification.
--
-- When SignatureFailed is return, the signature shouldn't be
-- accepted.
--
-- Other values are only useful to differentiate the failure
-- reason, but are all equivalent to failure.
data SignatureVerification
= -- | verification succeeded
SignaturePass
| -- | verification failed
SignatureFailed SignatureFailure
deriving (Show, Eq)
-- | Various failure possible during signature checking
data SignatureFailure
= -- | signature doesn't verify
SignatureInvalid
| -- | algorithm and public key mismatch, cannot proceed
SignaturePubkeyMismatch
| -- | unimplemented signature algorithm
SignatureUnimplemented
deriving (Show, Eq)
-- | Verify a Signed object against a specified public key
verifySignedSignature
:: (Show a, Eq a, ASN1Object a)
=> SignedExact a
-> PubKey
-> SignatureVerification
verifySignedSignature signedObj pubKey =
verifySignature
(signedAlg signed)
pubKey
(getSignedData signedObj)
(signedSignature signed)
where
signed = getSigned signedObj
-- | verify signature using parameter
verifySignature
:: SignatureALG
-- ^ Signature algorithm used
-> PubKey
-- ^ Public key to use for verify
-> ByteString
-- ^ Certificate data that need to be verified
-> ByteString
-- ^ Signature to verify
-> SignatureVerification
verifySignature (SignatureALG_Unknown _) _ _ _ = SignatureFailed SignatureUnimplemented
verifySignature (SignatureALG hashALG PubKeyALG_RSAPSS) pubkey cdata signature = case verifyF pubkey of
Nothing -> SignatureFailed SignatureUnimplemented
Just f ->
if f cdata signature
then SignaturePass
else SignatureFailed SignatureInvalid
where
verifyF (PubKeyRSA key)
| hashALG == HashSHA256 = Just $ PSS.verify (PSS.defaultPSSParams SHA256) key
| hashALG == HashSHA384 = Just $ PSS.verify (PSS.defaultPSSParams SHA384) key
| hashALG == HashSHA512 = Just $ PSS.verify (PSS.defaultPSSParams SHA512) key
| hashALG == HashSHA224 = Just $ PSS.verify (PSS.defaultPSSParams SHA224) key
| otherwise = Nothing
verifyF _ = Nothing
verifySignature (SignatureALG hashALG pubkeyALG) pubkey cdata signature
| pubkeyToAlg pubkey == pubkeyALG = case verifyF pubkey of
Nothing -> SignatureFailed SignatureUnimplemented
Just f ->
if f cdata signature
then SignaturePass
else SignatureFailed SignatureInvalid
| otherwise = SignatureFailed SignaturePubkeyMismatch
where
verifyF (PubKeyRSA key) = Just $ rsaVerify hashALG key
verifyF (PubKeyDSA key)
| hashALG == HashSHA1 = Just $ dsaVerify SHA1 key
| hashALG == HashSHA224 = Just $ dsaVerify SHA224 key
| hashALG == HashSHA256 = Just $ dsaVerify SHA256 key
| otherwise = Nothing
verifyF (PubKeyEC key) = verifyECDSA hashALG key
verifyF _ = Nothing
dsaToSignature :: ByteString -> Maybe DSA.Signature
dsaToSignature b =
case decodeASN1' BER b of
Left _ -> Nothing
Right asn1 ->
case asn1 of
Start Sequence : IntVal r : IntVal s : End Sequence : _ ->
Just $ DSA.Signature{DSA.sign_r = r, DSA.sign_s = s}
_ ->
Nothing
dsaVerify hsh key b a =
case dsaToSignature a of
Nothing -> False
Just dsaSig -> DSA.verify hsh key dsaSig b
rsaVerify HashMD2 = RSA.verify (Just MD2)
rsaVerify HashMD5 = RSA.verify (Just MD5)
rsaVerify HashSHA1 = RSA.verify (Just SHA1)
rsaVerify HashSHA224 = RSA.verify (Just SHA224)
rsaVerify HashSHA256 = RSA.verify (Just SHA256)
rsaVerify HashSHA384 = RSA.verify (Just SHA384)
rsaVerify HashSHA512 = RSA.verify (Just SHA512)
verifySignature (SignatureALG_IntrinsicHash pubkeyALG) pubkey cdata signature
| pubkeyToAlg pubkey == pubkeyALG = doVerify pubkey
| otherwise = SignatureFailed SignaturePubkeyMismatch
where
doVerify (PubKeyEd25519 key) = eddsa Ed25519.verify Ed25519.signature key
doVerify (PubKeyEd448 key) = eddsa Ed448.verify Ed448.signature key
doVerify _ = SignatureFailed SignatureUnimplemented
eddsa verify toSig key =
case toSig signature of
CryptoPassed sig
| verify key cdata sig -> SignaturePass
| otherwise -> SignatureFailed SignatureInvalid
CryptoFailed _ -> SignatureFailed SignatureInvalid
verifyECDSA :: HashALG -> PubKeyEC -> Maybe (ByteString -> ByteString -> Bool)
verifyECDSA hashALG key =
ecPubKeyCurveName key >>= verifyCurve (pubkeyEC_pub key)
where
verifyCurve pub curveName = Just $ \msg sigBS ->
case decodeASN1' BER sigBS of
Left _ -> False
Right [Start Sequence, IntVal r, IntVal s, End Sequence] ->
let curve = ECC.getCurveByName curveName
in case unserializePoint curve pub of
Nothing -> False
Just p ->
let pubkey = ECDSA.PublicKey curve p
in (ecdsaVerify hashALG) pubkey (ECDSA.Signature r s) msg
Right _ -> False
ecdsaVerify HashMD2 = ECDSA.verify MD2
ecdsaVerify HashMD5 = ECDSA.verify MD5
ecdsaVerify HashSHA1 = ECDSA.verify SHA1
ecdsaVerify HashSHA224 = ECDSA.verify SHA224
ecdsaVerify HashSHA256 = ECDSA.verify SHA256
ecdsaVerify HashSHA384 = ECDSA.verify SHA384
ecdsaVerify HashSHA512 = ECDSA.verify SHA512