hvr / hs-cryptohash

efficient and practical cryptohashing in haskell

CryptoHash

hs-cryptohash provides many different secure digest algorithms, also called cryptographic hash functions or, simply, cryptohashes. The package exports common hash functions, as well as some more exotic ones, and provides a single API for them all.

The general performance is comparable to the most optimised implementations available.

Here is the complete list of supported algorithms:

• MD2, MD4, MD5
• RIPEMD160
• SHA1
• SHA-2 family: 224, 256, 384, 512 and the newer 512t
• SHA-3 (aka Keccak)
• Skein: 256, 512
• Tiger
• Whirlpool

You can easily import any hash with the following:

import qualified Crypto.Hash.<HASH> as <Hash>

We recommend using import qualified because the APIs are similar and many of the modules reuse the same names. However, if you are ony using one module, there is no need to qualify the names.

Incremental API

it's based on 4 different functions, similar to the lowlevel operations of a typical hash:

• init: create a new hash context
• update: update non-destructively a new hash context with a strict bytestring
• updates: same as update, except that it takes a list of strict bytestring
• finalize: finalize the context and returns a digest bytestring.

all those operations are completely pure, and instead of changing the context as usual in others language, it re-allocates a new context each time.

One Pass API

The one pass API use the incremental API under the hood, but expose common operations to create digests out of a bytestring and lazy bytestring.

• hash: create a digest (init+update+finalize) from a strict bytestring
• hashlazy: create a digest (init+update+finalize) from a lazy bytestring

More Type safety

A more type safe API is also available from Crypto.Hash. The API provides all the supported hashes in the same namespace, through unified functions.

It introduces 2 new types, the Context type and the Digest type. Both those types are parametrized with the HashAlgorithm used.

The API is very similar to each single hash module, except the types are slightly different.

import Crypto.Hash

-- use the incremental API to hash the byte [1,2,3] with SHA1
-- and print the hexadecimal digest.
example1 = do
    let ctx = hashInit
        ctx' = hashUpdates ctx [ Data.ByteString.pack [1,2,3] ]
        dgt  = hashFinalize ctx' :: Digest SHA1
    putStrLn $ show dgt

-- use the one-pass API to hash the byte 1,2,3 with SHA3_512
-- and print the hexadecimal digest.
example2 = do
    let dgt  = hash (Data.ByteString.pack [1,2,3]) :: Digest SHA3_512
    putStrLn $ show dgt

Performance

Cryptohash uses C implementations to provide maximum performance. see the cbits directory for more information