80 lines
1.9 KiB
JavaScript
80 lines
1.9 KiB
JavaScript
import {getCurveFromName, Scalar} from "ffjavascript";
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import ethers from "ethers";
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const SEED = "mimc";
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const NROUNDS = 91;
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export default async function buildMimc7() {
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const bn128 = await getCurveFromName("bn128");
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return new Mimc7(bn128.Fr);
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}
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class Mimc7 {
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constructor (F) {
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this.F = F;
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this.cts = this.getConstants(SEED, 91);
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}
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getIV(seed) {
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const F = this.F;
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if (typeof seed === "undefined") seed = SEED;
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const c = ethers.utils.keccak256(ethers.utils.toUtf8Bytes(seed+"_iv"));
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const cn = Scalar.e(c);
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const iv = Scalar.mod(cn, F.p);
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return iv;
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};
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getConstants(seed, nRounds) {
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const F = this.F;
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if (typeof seed === "undefined") seed = SEED;
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if (typeof nRounds === "undefined") nRounds = NROUNDS;
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const cts = new Array(nRounds);
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let c = ethers.utils.keccak256(ethers.utils.toUtf8Bytes(SEED));
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for (let i=1; i<nRounds; i++) {
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c = ethers.utils.keccak256(c);
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cts[i] = F.e(c);
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}
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cts[0] = F.e(0);
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return cts;
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}
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hash (_x_in, _k) {
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const F = this.F;
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const x_in = F.e(_x_in);
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const k = F.e(_k);
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let r;
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for (let i=0; i<NROUNDS; i++) {
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const c = this.cts[i];
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const t = (i==0) ? F.add(x_in, k) : F.add(F.add(r, k), c);
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const t2 = F.square(t);
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const t4 = F.square(t2);
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r = F.mul(F.mul(t4, t2), t);
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}
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return F.add(r, k);
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}
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multiHash(arr, key) {
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const F = this.F;
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let r;
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if (typeof(key) === "undefined") {
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r = F.zero;
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} else {
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r = key;
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}
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for (let i=0; i<arr.length; i++) {
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r = F.add(
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F.add(
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r,
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arr[i]
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),
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this.hash(F.e(arr[i]), r)
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);
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}
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return r;
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}
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}
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