Crypto Multihash

Multihash library implemented on top of cryptonite cryptographic library. Multihash is a protocol for encoding the hash algorithm and digest length at the start of the digest, see the official multihash github page.

This library is still experimental and the api is not guaranteed stable. I will increment the version number appropriately in case of breaking changes.

For the moment the library implements all the expected hashing algorithms with the exception of shake-128 and shake-256. A Multihash can be encoded in hex (Base16), bitcoin base58 (Base58) and base64 (Base64).

The Base32 encoding is not yet supported due to discrepancy between the encoding from Data.ByteArray.Encoding and the one appearing in the official multihash page.

Usage

{-# LANGUAGE OverloadedStrings #-}

import Crypto.Multihash
import Data.ByteString (ByteString)
import Data.ByteString.Char8 (pack)

main = do
    let v = "test"::ByteString
    let m = multihash SHA256 v
    putStrLn $ "Base16: " ++ (encode Base16 m)
    putStrLn $ "Base58: " ++ (encode Base58 m)
    putStrLn $ "Base64: " ++ (encode Base64 m)
    
    let h = encode' Base58 m
    let h8 = (Data.ByteString.Char8.pack h)
    checkMultihash h8 v
    -- Right True

Test

Some preliminary tests can be performed with stack test.

A simple example encoder is in app/Main.hs. You can run it on files

echo -n test | stack exec mh -- somefile someotherfile

or read data from the standard input

echo -n test | stack exec mh -- -`

Contribution

1. Fork repository
2. Do some changes
3. Create pull request
4. Wait for CI build and review

You can use stack to build the project: stack build

To run tests: stack test

TODO

• Improve documentation
• Implement hash checker that takes some data and an encoded multihash and check that the multihash corresponds to the data (inferring automatically the appropriate hash function)
• Evaluate if throwing an error in the encode function is the wanted behaviour and anyway implement a safe version returning an Either type
• Add testing for the newly introduced checker and for raised exceptions
• Add multihash checker into the cli example
• Implement shake-128 and shake-256 multihashes
• Implement Base32 encoding waiting for https://github.com/jbenet/multihash/issues/31 to be resolved)