37 lines
1 KiB
Haskell
37 lines
1 KiB
Haskell
{- values verified using a shared secret
|
|
-
|
|
- Copyright 2012 Joey Hess <joey@kitenet.net>
|
|
-
|
|
- License: BSD-2-clause
|
|
-}
|
|
|
|
module Utility.Verifiable where
|
|
|
|
import Data.Digest.Pure.SHA
|
|
import Data.ByteString.Lazy.UTF8 (fromString)
|
|
import qualified Data.ByteString.Lazy as L
|
|
|
|
type Secret = L.ByteString
|
|
type HMACDigest = String
|
|
|
|
{- A value, verifiable using a HMAC digest and a secret. -}
|
|
data Verifiable a = Verifiable
|
|
{ verifiableVal :: a
|
|
, verifiableDigest :: HMACDigest
|
|
}
|
|
deriving (Eq, Read, Show)
|
|
|
|
mkVerifiable :: Show a => a -> Secret -> Verifiable a
|
|
mkVerifiable a secret = Verifiable a (calcDigest (show a) secret)
|
|
|
|
verify :: (Eq a, Show a) => Verifiable a -> Secret -> Bool
|
|
verify v secret = v == mkVerifiable (verifiableVal v) secret
|
|
|
|
calcDigest :: String -> Secret -> HMACDigest
|
|
calcDigest v secret = showDigest $ hmacSha1 secret $ fromString v
|
|
|
|
{- for quickcheck -}
|
|
prop_verifiable_sane :: String -> String -> Bool
|
|
prop_verifiable_sane a s = verify (mkVerifiable a secret) secret
|
|
where
|
|
secret = fromString s
|