filosottile/powersoftau

An independent implementation of the Powers of Tau MPC ceremony.

powersoftau

powersoftau is an independent implementation of the Powers of Tau MPC ceremony.

It is written in Go, shares no code with the main Rust implementation, and uses the RELIC toolkit for BLS12-381.

Installation

You will need a recent version of Go (1.9+ is known to work) and a C compiler.

git clone --recursive https://github.com/FiloSottile/powersoftau $(go env GOPATH)/src/github.com/FiloSottile/powersoftau
cd $(go env GOPATH)/src/github.com/FiloSottile/powersoftau && make
export CGO_LDFLAGS_ALLOW=".*\.a" # only needed for Go version 1.9.4
go install github.com/FiloSottile/powersoftau/cmd/taucompute
$(go env GOPATH)/bin/taucompute --help

Usage

Usage of taucompute:
  -challenge string
    	path to the challenge file (default "./challenge")
  -next string
    	path to the next challenge file, optional
  -pprof
    	run a profiling server; use ONLY FOR DEBUGGING
  -response string
    	path to the response file (default "./response")

To facilitate running multiple implementations of Powers of Tau, you can run taucompute with the -next flag, which will also write a new challenge file once done with the computation. NOTE: you will have to submit both response files.

powersoftau's Issues

Verifier

It seems like it would be easy to build the verifier in this codebase too.
The verify_transform function in Sean's codebase is a reference for verifier functionality (though don't look ). In any case it's confusing to me how to use that. Since we're mostly posting response files online, rather than challenge files, you'd have to get the previous challenge file to verify the ZcashFoundation/powersoftau-attestations blockchain. This could be an issue on Sean's github too, but it's also nice that codebase has been stable.

Verify or replace G2 coefficient value

The G2 coefficient value, used to scale in hash_to_g2, was copied verbatim from the Rust implementation. It should be checked, or replaced with a RELIC function.

powersoftau/bls12/g2.c

Line 33 in ce98e03

bn_read_str(k, "5d543a95414e7f1091d50792876a202cd91de4547085abaa68a205b2e5a7ddfa628f1cb4d9e82ef21537e293a6691ae1616ec6e786f0c70cf1c38e31c7238e5", 127, 16); // FROM RUST IMPLEMENTATION // TODO: verify

Upstream issue: relic-toolkit/relic#64

Origin story?

Thanks for this awesome contribution, I've been really hoping to see an independent implementation of the Powers of Tau code.

You mentioned in your public debut at the zapps-wg mailing list that you were sponsored by Zcash Co. Could you share some details here about how that worked?