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module Sproxy.Application.State (
decode
, encode
) where
import Data.ByteString (ByteString)
import Data.ByteString.Lazy (fromStrict, toStrict)
import Data.Digest.Pure.SHA (hmacSha1, bytestringDigest)
import qualified Data.ByteString.Base64 as Base64
import qualified Data.Serialize as DS
-- FIXME: Compress / decompress ?
encode :: ByteString -> ByteString -> ByteString
encode key payload = Base64.encode . DS.encode $ (payload, digest key payload)
decode :: ByteString -> ByteString -> Either String ByteString
decode key d = do
(payload, dgst) <- DS.decode =<< Base64.decode d
if dgst /= digest key payload
then Left "junk"
else Right payload
digest :: ByteString -> ByteString -> ByteString
digest key payload = toStrict . bytestringDigest $ hmacSha1 (fromStrict key) (fromStrict payload)
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