@cloudflare/zkp-ecdsa

zkp-ecdsa

This is a TypeScript library for Zero-Knowledge proof for ECDSA.

It enables proving knowledge of a ECDSA-P256 signature under one of many public keys that are stored in an accumulator or in a list.

Specification

See branch paper of this repository.

Functional Spec.

Proof using Groth-Kohlweiss.

GK Paper: https://eprint.iacr.org/2014/764

import {
    SignatureProofList,
    SystemParametersList,
    generateParamsList,
    keyToInt,
    proveSignatureList,
    verifySignatureList,
} from '../src/zkpAttestList.js'

const keyPair = await crypto.subtle.generateKey(
    { name: 'ECDSA', namedCurve: 'P-256' },
    true,
    [ 'sign', 'verify']),
    enc = new TextEncoder(),
    msg = enc.encode('kilroy was here'),
    msgHash = new Uint8Array(await crypto.subtle.digest('SHA-256', msg)),
    signature = new Uint8Array(
        await crypto.subtle.sign({ name: 'ECDSA', hash: 'SHA-256' }, keyPair.privateKey, msg)
    )

const testKey = await keyToInt(keyPair.publicKey),
  testArray = [testKey, BigInt(4), BigInt(5), BigInt(6), BigInt(7), BigInt(8)],
  params = generateParamsList(),
  proof = await proveSignatureList(
    params,
    msgHash,
    signature,
    keyPair.publicKey,
    0,
    testArray
  ),
  success = await verifySignatureList(params, msgHash, testArray, proof)

Proof using RSA Accumulators.

import {
    SignatureProofAccumulator,
    SystemParametersAccumulator,
    addKeyToAccumulator,
    generateParamsAccumulator,
    proveSignatureAccumulator,
    verifySignatureAccumulator
} from '../src/zkpAttestAcc.js'

import { Accumulator } from '../src/rsaAccumulator.js'

const keyPair = await crypto.subtle.generateKey(
    { name: 'ECDSA', namedCurve: 'P-256' },
    true,
    [ 'sign', 'verify']),
    enc = new TextEncoder(),
    msg = enc.encode('kilroy was here'),
    msgHash = new Uint8Array(await crypto.subtle.digest('SHA-256', msg)),
    signature = new Uint8Array(
        await crypto.subtle.sign({ name: 'ECDSA', hash: 'SHA-256' }, keyPair.privateKey, msg)
    )
const { system: params, accumulator: initAcc } = generateParamsAccumulator(),
    { j, acc, witness } = await addKeyToAccumulator(params, initAcc, keyPair.publicKey),
    proof = await proveSignatureAccumulator(
        params,
        msgHash,
        signature,
        keyPair.publicKey,
        j,
        witness,
        acc
    ),
    success = await verifySignatureAccumulator(params, msgHash, acc, proof)

---

Building

 $ npm ci
 $ npm run build

Testing

 $ npm ci
 $ npm run build
 $ npm run test

---

Future Work / Possible enhancements

• Accelerate verification in another language.
• Use private key so accumulator doesn't change and invalidate older witnesses.

---

Development Environment

Benchmark

 $ npm ci
 $ npm run bench

Flamegraph

 $ npm ci
 $ npm run flame

Webpack

This package compiles to ESModules (instead of CommonJS). More info about ESModules. Requires to have webpack installed.

 $ npm ci
 $ npm run build
 $ webpack --config webpack.config.cjs

Linter & Formatter

 $ npm ci
 $ npm run lint
 $ npm run lint:fix
 $ npm run format