cpp-etchash

C/C++ implementation of Etchash – the Ethereum Classic Proof of Work algorithm

Networks

This branch is configured for Ethereum Classic mainnet. For mordor use the mordor branch.

Table of Contents

• Install
• Usage
• Test vectors
• Optimizations
• Maintainer
• License

Install

Build from source using CMake.

mkdir build
cd build
cmake ..
cmake --build .

Usage

See ethash.hpp for list of exported function and documentation.

Test vectors

• ProgPoW test vectors

Optimizations

This section decscribes the optimizations, modification and tweaks applied in this library in relation to Ethash reference implementation.

The library contains a set of micro-benchmarks. Build and run bench tool.

Seed hash is computed on the fly.

Seed hash is sequence of keccak256 hashes applied the epoch number of times. Time needed to compute seed hash is negligible comparing to time needed to build light cache. Computing seed hash for epoch 10000 takes ~ 5 ms, building light cache for epoch 1 takes ~ 500 ms.

Dataset size is computed on the fly

Computing the size of full dataset and light cache requires finding the largest prime number given an upper bound. For similar reasons as with seed hash, this is computed on the fly. The procedure used is quite naive and forks well only up to 40-bit number, so some additional improvement can be done in future.

Maintainer

Paweł Bylica @chfast

License

Licensed under the Apache License, Version 2.0.