web3-tools

A Haskell library providing simple, reusable cryptographic utilities for Web3 development.

This is a small, focused library that I maintain and expand as needed. Contributions, feature requests, and suggestions are always welcome!

Features

• Ethereum signature verification - Verify ECDSA signatures against addresses
• Address recovery - Recover Ethereum addresses from message signatures
• Secp256k1 operations - Low-level elliptic curve cryptography via FFI
• Keccak256 hashing - Ethereum-compatible hash function

Module Structure

The library is organized to separate chain-agnostic crypto primitives from blockchain-specific implementations:

Crypto.*              -- Shared cryptographic primitives
  Crypto.Hash.Keccak  -- Keccak256 hashing
  Crypto.Secp256k1.*  -- Elliptic curve operations

Eth.*                 -- Ethereum-specific functionality
  Eth.Address         -- Signature verification and address recovery

This makes it easy to add support for other blockchains while reusing common cryptographic building blocks.

Installation

Requirements:

• libsecp256k1-devel (or libsecp256k1-dev on Debian/Ubuntu)

Using Stack:

stack build

Usage Example

{-# LANGUAGE OverloadedStrings #-}
import Eth.Address (verifySignature)

-- Verify an Ethereum signature
main :: IO ()
main = do
  let message = "Hello, Web3!"
      signature = ... -- 65-byte signature (r || s || v)
      address = ...   -- 20-byte Ethereum address

  isValid <- verifySignature message signature address
  print isValid

Contributing

This library grows based on practical needs. If you:

• Need a specific feature for your project
• Found a bug or issue
• Have suggestions for improvements
• Want to add support for another blockchain

Feel free to open an issue or submit a PR!

License

MIT - See LICENSE file for details