micro-zk-proofs/msm.js

Create & verify zero-knowledge SNARK proofs in parallel, using noble cryptography

/**
 * MSM - Multi Scalar Multiplication. Done in parallel using micro-wrkr.
 * MSM is a fast algorithm to add & multiply many elliptic curve points at once.
 * @module
 */
import {} from '@noble/curves/abstract/modular.js';
import { bn254 } from '@noble/curves/bn254.js';
import { wrkr } from 'micro-wrkr';
import {} from "./msm-worker.js";
function reducePoint(p) {
    return (lst) => lst.map((i) => new p(i.X, i.Y, i.Z)).reduce((acc, i) => acc.add(i), p.ZERO);
}
/**
 * Initializes batched MSM workers and reduction helpers.
 * @returns Worker methods together with a `terminate()` hook.
 * @example
 * Create the bn254 worker pool and terminate it when the batch work is done.
 * ```ts
 * const ctx = initMSM();
 * ctx.terminate();
 * ```
 */
export function initMSM() {
    const { methods, terminate } = wrkr.initBatch(() => new Worker(new URL('./msm-worker.js', import.meta.url), { type: 'module' }), {
        bn254_msmG1: reducePoint(bn254.G1.Point),
        bn254_msmG2: reducePoint(bn254.G2.Point),
    });
    return { methods, terminate };
}
/**
 * Adapts a worker MSM function into the point-array/scalar-array shape used by Groth16.
 * @param field - Scalar field used to drop zero scalars.
 * @param point - Projective point constructor for normalization.
 * @param fn - Worker-backed MSM implementation.
 * @returns Helper that accepts separate point and scalar arrays.
 * @example
 * Wrap a worker MSM function so Groth16 can call it with separate point and scalar arrays.
 * ```ts
 * const { bn254 } = await import('@noble/curves/bn254.js');
 * const workerMsm = async () => bn254.G1.Point.ZERO;
 * const msm = modifyArgs(bn254.fields.Fr, bn254.G1.Point, workerMsm);
 * await msm([bn254.G1.Point.BASE], [1n]);
 * ```
 */
export function modifyArgs(field, point, fn) {
    return async (points, scalars) => {
        if (points.length !== scalars.length)
            throw new Error('points.length !== scalars.length');
        const input = [];
        for (let i = 0; i < points.length; i++) {
            const scalar = scalars[i];
            if (field.is0(scalar))
                continue;
            input.push({ point: points[i], scalar });
        }
        // NOTE: buildGroth accepts curve and can be build with different version of @noble/curves,
        // so we convert it here.
        const res = (await fn(input));
        return res instanceof point ? res : new point(res.px, res.py, res.pz);
    };
}
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