On Sat, Sep 4, 2010 at 3:23 AM, Heinrich Apfelmus
A better reason is the data structure has no way to implement generateKeyPair.
That's a non-problem: each algorithm (RSA, DSA, ...) implements a function with the same type as generateKeyPair . Compare
rsa :: RangomGen g => BitLength -> g -> ((Key,Key), g)
vs
((k1 :: RSA, k2), g') = generateKeyPair g
You always have to write down the name of the algorithm ("RSA") when using generateKeyPair , so you may as well drop it entirely.
That simply isn't true. What if you have a key exchange in which the ephemeral key is of the same type as your signing key? Slightly contrived example: buildAgreementMessage :: (Monad m, CryptoRandomGen g, ASymetricCipher k) => g -> k -> m (B.ByteString,g) buildAgreementMessages g k = do (e,g') <- liftM eitherToFail (buildAsymKey g `asTypeOf` k) let eBS = encode e msg = runPut (putByteString agreementHeader >> putWord16be (B.length eBS) >> putByteString eBS) return msg