SRI - Update Circom Circuit to use Eddsa Signature verification

[biscuitdey]

Overview

Previously we accepted only Ecdsa signatures in the SRI because we used Metamask to login and Metamask used Ecdsa signatures. But Ecdsa signature verification inside circom zk circuits is very inefficient & the available alternatives are not widely used (causing issues with interoperability). Keeping these issues in mind, SRI team has decided to use Eddsa signatures.

Reference

PR #752

Tasks

• Remove Ecdsa sig verifier
• Add Eddsa sig verifier to circom circuit
• Prepare circuit inputs to accept Eddsa signature

[biscuitdey]

@Therecanbeonlyone1969 Is there any library you recommend for generating Eddsa signatures? I found the following libraries :

1. @transmute/ed25519-signature-2018
2. @digitalcredentials/ed25519-signature-2020
3. @digitalbazaar/ed25519-signature-2020

[Therecanbeonlyone1969]

@biscuitdey here you go https://github.com/paulmillr/noble-curves

[Therecanbeonlyone1969]

@biscuitdey also circomlibjs supports EdDSA sigs such as with MimC e.g.

const buildEddsa = require("circomlibjs").buildEddsa;
import * as crypto from "crypto";

const SNARK_SCALAR_FIELD = 21888242871839275222246405745257275088548364400416034343698204186575808495617n;
const genRandomBabyJubValue = () => {
  // Prevent modulo bias
  //const lim = BigInt('0x10000000000000000000000000000000000000000000000000000000000000000')
  //const min = (lim - SNARK_FIELD_SIZE) % SNARK_FIELD_SIZE
  const min = BigInt("6350874878119819312338956282401532410528162663560392320966563075034087161851");

  let rand;
  // eslint-disable-next-line no-constant-condition
  while (true) {
    rand = BigInt("0x" + crypto.randomBytes(32).toString("hex"));

    if (rand >= min) {
      break;
    }
  }

  const privKey = rand % SNARK_SCALAR_FIELD;

  return privKey;
};

async function eddsasig() {
    const eddsa = await buildEddsa();
    const plaintext = rand = BigInt("0x" + crypto.randomBytes(32).toString("hex"));
    const F = eddsa.F;
    const issuerPrivKey = genRandomBabyJubValue();
    const issuerPubKey = eddsa.prv2pub(issuerPrivKey.toString());
    const signature = eddsa.signMiMC(issuerPrivKey.toString(), F.e(plaintext));

    return signature;
    }

[biscuitdey]

@Therecanbeonlyone1969

@biscuitdey also circomlibjs supports EdDSA sigs such as with MimC e.g.

const buildEddsa = require("circomlibjs").buildEddsa;
import * as crypto from "crypto";

const SNARK_SCALAR_FIELD = 21888242871839275222246405745257275088548364400416034343698204186575808495617n;
const genRandomBabyJubValue = () => {
  // Prevent modulo bias
  //const lim = BigInt('0x10000000000000000000000000000000000000000000000000000000000000000')
  //const min = (lim - SNARK_FIELD_SIZE) % SNARK_FIELD_SIZE
  const min = BigInt("6350874878119819312338956282401532410528162663560392320966563075034087161851");

  let rand;
  // eslint-disable-next-line no-constant-condition
  while (true) {
    rand = BigInt("0x" + crypto.randomBytes(32).toString("hex"));

    if (rand >= min) {
      break;
    }
  }

  const privKey = rand % SNARK_SCALAR_FIELD;

  return privKey;
};

async function eddsasig() {
    const eddsa = await buildEddsa();
    const plaintext = rand = BigInt("0x" + crypto.randomBytes(32).toString("hex"));
    const F = eddsa.F;
    const issuerPrivKey = genRandomBabyJubValue();
    const issuerPubKey = eddsa.prv2pub(issuerPrivKey.toString());
    const signature = eddsa.signMiMC(issuerPrivKey.toString(), F.e(plaintext));

    return signature;
    }

I am using this same library

[ognjenkurtic]

Currently blocked by #765