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authorGravatar Joey Hess <joey@kitenet.net>2012-09-07 23:23:52 -0400
committerGravatar Joey Hess <joey@kitenet.net>2012-09-07 23:23:52 -0400
commit92df8250fa7c6d8c36ca214e45c7b5a6c9d307a9 (patch)
tree31dff3d544a99f3b53a2a4747d9286dbd52c5b2a /Utility
parentc12caf0a4e665d121c7ffd5a992306f7511bc305 (diff)
broke out Verifiable to a utility library, and added a quickcheck test
Diffstat (limited to 'Utility')
-rw-r--r--Utility/Verifiable.hs37
1 files changed, 37 insertions, 0 deletions
diff --git a/Utility/Verifiable.hs b/Utility/Verifiable.hs
new file mode 100644
index 000000000..58218db2a
--- /dev/null
+++ b/Utility/Verifiable.hs
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+{- values verified using a shared secret
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+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
+ { val :: a
+ , digest :: HMACDigest
+ }
+ deriving (Eq, Read, Show)
+
+mkVerifiable :: Show a => a -> Secret -> Verifiable a
+mkVerifiable a secret = Verifiable a (calcDigest (show a) secret)
+
+verified :: (Eq a, Show a) => Verifiable a -> Secret -> Bool
+verified v secret = v == mkVerifiable (val 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 = verified (mkVerifiable a secret) secret
+ where
+ secret = fromString s