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{- Copyright 2017 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE OverloadedStrings, RankNTypes, DeriveGeneric #-}
module Crypto where
import Val
import Hash
import Types
import qualified Crypto.PubKey.Ed25519 as Ed25519
import Crypto.Error
import Crypto.Random.Entropy
import Data.ByteArray (convert)
import qualified Data.ByteString as B
import qualified Data.Semigroup as Sem
dummySignature :: Signature
dummySignature = OtherSignature (Val mempty)
class Signed t where
getSignature :: t -> Signature
hashExceptSignature :: t -> Hash
mkSigned :: MySessionKey -> (Signature -> t) -> t
mkSigned sk mk =
let tmp = mk dummySignature
in mk (sign sk tmp)
instance Hashable a => Signed (Activity a) where
getSignature = activitySignature
hashExceptSignature (Activity a mpa mpe mt _s) = hash $
Tagged "Activity" [hash a, hashOfMaybeUnsafe mpa, hashOfMaybeUnsafe mpe, hash mt]
instance Signed Control where
getSignature = controlSignature
hashExceptSignature (Control a _s) = hash $
Tagged "Control" a
instance Hashable t => Signed (Message t) where
getSignature (ActivityMessage a) = getSignature a
getSignature (ControlMessage c) = getSignature c
hashExceptSignature (ActivityMessage a) = hashExceptSignature a
hashExceptSignature (ControlMessage c) = hashExceptSignature c
instance Signed AnyMessage where
getSignature (User m) = getSignature m
getSignature (Developer m) = getSignature m
hashExceptSignature (User m) = hashExceptSignature m
hashExceptSignature (Developer m) = hashExceptSignature m
sign :: Signed v => MySessionKey -> v -> Signature
sign (MySessionKey sk pk) v = Ed25519Signature $ Val $ convert $
Ed25519.sign sk pk (toSign v)
toSign :: Signed v => v -> B.ByteString
toSign = val . hashValue . hashExceptSignature
-- | Verifiy the signature of a Signed value.
verifySigned :: Signed v => SigVerifier -> v -> Bool
verifySigned (SigVerifier _ verifier) v =
case getSignature v of
Ed25519Signature (Val s) ->
case Ed25519.signature s of
CryptoPassed sig -> verifier (toSign v) sig
CryptoFailed _ -> False
OtherSignature _ -> False
data SigVerifier = SigVerifier Int (B.ByteString -> Ed25519.Signature -> Bool)
instance Show SigVerifier where
show (SigVerifier n _) = "SigVerifier (" ++ show n ++ ")"
mkSigVerifier :: PublicKey -> SigVerifier
mkSigVerifier (PublicKey (Val pk)) =
case Ed25519.publicKey pk of
CryptoPassed pk' -> SigVerifier 1 (Ed25519.verify pk')
CryptoFailed _ -> mempty
instance Sem.Semigroup SigVerifier where
SigVerifier na a <> SigVerifier nb b =
SigVerifier (na+nb) $ \d s -> b d s || a d s
instance Monoid SigVerifier where
mempty = SigVerifier 0 $ \_b _s -> False
mappend = (Sem.<>)
data MySessionKey = MySessionKey Ed25519.SecretKey Ed25519.PublicKey
instance Show MySessionKey where
show _ = "<MySessionKey>"
genMySessionKey :: IO MySessionKey
genMySessionKey = do
-- Crypto.Random.Entropy may use rdrand, or /dev/random.
-- Even if you don't trust rdrand to be free of backdoors,
-- it seems safe enough to use it for a session key that
-- is only used for signing, not encryption.
rand32 <- getEntropy 32 :: IO B.ByteString
sk <- throwCryptoErrorIO $ Ed25519.secretKey rand32
return $ MySessionKey sk (Ed25519.toPublic sk)
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