multisetups

For production use, Groth16 zk-SNARK circuits require a multi-party trusted setup to generate the proving and verifying key fo reach circuit, while reducing the probability that the toxic waste associated with the keys has been retained. While there already exist (1, 2, 3) which help teams to automate this process, so far none exist that support this combination of requirements:

1. Multiple circuits per ceremony (e.g. MACI)
2. Large circuits (more than 1 million constraints) that cannot be set up in a browser

The multisetups utility seeks to meet them with the following goals in mind:

1. Simplicity:

   • Rather than automate away the role of a central coordinator, a coordinator is needed to verify contributions and pass the baton on to the next participant. Moreover, doing so reduces the time and cost of development.

2. Ease of use for contributors:

   • Contributors should only have to run a few commands to participate in the ceremony. Moreover, the software will be Dockerised for maximum ease-of-use.

3. Low infrastructure overhead:

   • Contribution files should be transferred via IPFS, so it is not necessary to provision cloud machines for the ceremony. As long as the coordinator has high bandwidth and storage, they can run the ceremony from their own machine.

Requirements

You need IPFS installed in your $PATH and you should run ipfs daemon in a separate terminal. This allows the coordinator and participants to easily share .zkey files.

Quick start with Docker

git clone git@github.com:weijiekoh/multisetups.git &&
cd multisetups &&
source scripts/git-snapshot.sh &&
docker-compose build &&
docker-compose up

To create a new ceremony with the sample .zkey files:

docker-compose exec multisetups node build/index.js init -d /multisetups/zkeys
Ceremony initialised. Please give this multihash to the first participant and keep your IPFS node running and connected to the IPFS network.
Qmeg59hpYk82DYmdupTgYTuZNedLeTKBJNQ2r38EpUqgYn

To download the ceremony files as a contributor:

docker-compose exec multisetups node build/index.js download -m Qmeg59hpYk82DYmdupTgYTuZNedLeTKBJNQ2r38EpUqgYn -d /ceremony/old

Saving file(s) to /ceremony/old
 247.36 KiB / 247.36 KiB [========================================] 100.00% 0s

To contribute:

docker-compose exec multisetups node build/index.js contribute -d /ceremony/old -n /ceremony/new

Contribution generated, and transcript written to /ceremony/new/transcript.1.txt.
Please run the 'attest' command next.

To generate an attestation file:

docker-compose exec multisetups node build/index.js attest -d /ceremony/new -t attestation.template.md

Wrote prepopulated attestation to /ceremony/new/attestation.1.md.
Please edit this file, sign it, and run the 'upload' subcommand.

To upload the contribution:

docker-compose exec multisetups node build/index.js upload -d /ceremony/new

Contribution uploaded. Please send this multihash to the coordinator and keep your IPFS node running and connected to the IPFS network.
QmYDsgWYRuHNYBeJABGZ6Csdj256jvj4E4WYX2dJ6w6iCj

Installation

git clone git@github.com:weijiekoh/multisetups.git &&
cd multisetups &&
npm i

Creating a new ceremony

First, create a zkeys directory and store all your .zkey files in it. You can use zkey-manager to create them.

Next, run:

node build/index.js init -d zkeys

You should see something like this:

Ceremony initialised. Please give this multihash to the first participant and keep your IPFS node running and connected to the IPFS network.
Qmeg59hpYk82DYmdupTgYTuZNedLeTKBJNQ2r38EpUqgYn

Contributing to a ceremony

First, download the .zkey files:

node build/index.js download -d ./old -m <MULTIHASH>.

Next, perform the contribution. This may take a long time. It should ideally be done on an airgapped computer.

node build/index.js contribute -m <MULTIHASH> -d ./old -n ./new

Generate an attestation file:

node build/index.js attest -d ./new -t attestation.template.md

Edit this attestation file to fill out the missing info, and sign it.

Finally, upload the files:

node build/index.js upload -n ./new