From 8e67a1e418e51c3ddf4d4b100d6bd61211a1a60b Mon Sep 17 00:00:00 2001
From: Joey Hess <joey@kitenet.net>
Date: Thu, 21 Nov 2013 13:24:14 -0400
Subject: add

---
 Utility/Hash.hs | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 Utility/Hash.hs

diff --git a/Utility/Hash.hs b/Utility/Hash.hs
new file mode 100644
index 0000000..cecc6af
--- /dev/null
+++ b/Utility/Hash.hs
@@ -0,0 +1,69 @@
+{- Convenience wrapper around cryptohash.
+ - Falls back to SHA if it's not available.
+ -}
+
+{-# LANGUAGE CPP #-}
+
+module Utility.Hash (
+	sha1,
+	sha224,
+	sha256,
+	sha384,
+	sha512,
+#ifdef WITH_CRYPTOHASH
+	skein256,
+	skein512,
+#endif
+	prop_hashes_stable
+) where
+
+import qualified Data.ByteString.Lazy as L
+import qualified Data.ByteString.Char8 as C8
+
+#ifndef WITH_CRYPTOHASH
+import Data.Digest.Pure.SHA
+#else
+import Crypto.Hash
+
+sha1 :: L.ByteString -> Digest SHA1
+sha1 = hashlazy
+
+sha224 :: L.ByteString -> Digest SHA224
+sha224 = hashlazy
+
+sha256 :: L.ByteString -> Digest SHA256
+sha256 = hashlazy
+
+sha384 :: L.ByteString -> Digest SHA384
+sha384 = hashlazy
+
+sha512 :: L.ByteString -> Digest SHA512
+sha512 = hashlazy
+
+-- sha3 is not yet fully standardized
+--sha3 :: L.ByteString -> Digest SHA3
+--sha3 = hashlazy
+
+skein256 :: L.ByteString -> Digest Skein256_256
+skein256 = hashlazy
+
+skein512 :: L.ByteString -> Digest Skein512_512
+skein512 = hashlazy
+
+#endif
+
+{- Check that all the hashes continue to hash the same. -}
+prop_hashes_stable :: Bool
+prop_hashes_stable = all (\(hasher, result) -> hasher foo == result)
+	[ (show . sha1, "0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33")
+	, (show . sha224, "0808f64e60d58979fcb676c96ec938270dea42445aeefcd3a4e6f8db")
+	, (show . sha256, "2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae")
+	, (show . sha384, "98c11ffdfdd540676b1a137cb1a22b2a70350c9a44171d6b1180c6be5cbb2ee3f79d532c8a1dd9ef2e8e08e752a3babb")
+	, (show . sha512, "f7fbba6e0636f890e56fbbf3283e524c6fa3204ae298382d624741d0dc6638326e282c41be5e4254d8820772c5518a2c5a8c0c7f7eda19594a7eb539453e1ed7")
+#ifdef WITH_CRYPTOHASH
+	, (show . skein256, "a04efd9a0aeed6ede40fe5ce0d9361ae7b7d88b524aa19917b9315f1ecf00d33")
+	, (show . skein512, "fd8956898113510180aa4658e6c0ac85bd74fb47f4a4ba264a6b705d7a8e8526756e75aecda12cff4f1aca1a4c2830fbf57f458012a66b2b15a3dd7d251690a7")
+#endif
+	]
+  where
+	foo = L.fromChunks [C8.pack "foo"]
-- 
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