circomlibjs/src/poseidon.js

108 lines
3.7 KiB
JavaScript

// Parameters are generated by a reference script https://extgit.iaik.tugraz.at/krypto/hadeshash/-/blob/master/code/generate_parameters_grain.sage
// Used like so: sage generate_parameters_grain.sage 1 0 254 2 8 56 0x30644e72e131a029b85045b68181585d2833e84879b9709143e1f593f0000001
// Using recommended parameters from whitepaper https://eprint.iacr.org/2019/458.pdf (table 2, table 8)
// Generated by https://extgit.iaik.tugraz.at/krypto/hadeshash/-/blob/master/code/calc_round_numbers.py
// And rounded up to nearest integer that divides by t
// Optimization is taken from https://github.com/filecoin-project/neptune
import assert from "assert";
import { getCurveFromName } from "ffjavascript";
import poseidonConstants from "./poseidon_constants_opt.js";
function unsringifyConstants(Fr, o) {
if ((typeof(o) == "string") && (/^[0-9]+$/.test(o) )) {
return Fr.e(o);
} else if ((typeof(o) == "string") && (/^0x[0-9a-fA-F]+$/.test(o) )) {
return Fr.e(o);
} else if (Array.isArray(o)) {
return o.map(unsringifyConstants.bind(null, Fr));
} else if (typeof o == "object") {
if (o===null) return null;
const res = {};
const keys = Object.keys(o);
keys.forEach( (k) => {
res[k] = unsringifyConstants(Fr, o[k]);
});
return res;
} else {
return o;
}
}
export default async function buildPoseidon() {
const bn128 = await getCurveFromName("bn128");
const F = bn128.Fr;
const opt = unsringifyConstants(F, poseidonConstants);
const N_ROUNDS_F = 8;
const N_ROUNDS_P = [56, 57, 56, 60, 60, 63, 64, 63, 60, 66, 60, 65, 70, 60, 64, 68];
const pow5 = a => F.mul(a, F.square(F.square(a, a)));
function poseidon(inputs) {
assert(inputs.length > 0);
assert(inputs.length <= N_ROUNDS_P.length);
const t = inputs.length + 1;
const nRoundsF = N_ROUNDS_F;
const nRoundsP = N_ROUNDS_P[t - 2];
const C = opt.C[t-2];
const S = opt.S[t-2];
const M = opt.M[t-2];
const P = opt.P[t-2];
let state = [F.zero, ...inputs.map(a => F.e(a))];
state = state.map((a, i) => F.add(a, C[i]));
for (let r = 0; r < nRoundsF/2-1; r++) {
state = state.map(a => pow5(a));
state = state.map((a, i) => F.add(a, C[(r +1)* t +i]));
state = state.map((_, i) =>
state.reduce((acc, a, j) => F.add(acc, F.mul(M[j][i], a)), F.zero)
);
}
state = state.map(a => pow5(a));
state = state.map((a, i) => F.add(a, C[(nRoundsF/2-1 +1)* t +i]));
state = state.map((_, i) =>
state.reduce((acc, a, j) => F.add(acc, F.mul(P[j][i], a)), F.zero)
);
for (let r = 0; r < nRoundsP; r++) {
state[0] = pow5(state[0]);
state[0] = F.add(state[0], C[(nRoundsF/2 +1)*t + r]);
const s0 = state.reduce((acc, a, j) => {
return F.add(acc, F.mul(S[(t*2-1)*r+j], a));
}, F.zero);
for (let k=1; k<t; k++) {
state[k] = F.add(state[k], F.mul(state[0], S[(t*2-1)*r+t+k-1] ));
}
state[0] =s0;
}
for (let r = 0; r < nRoundsF/2-1; r++) {
state = state.map(a => pow5(a));
state = state.map((a, i) => F.add(a, C[ (nRoundsF/2 +1)*t + nRoundsP + r*t + i ]));
state = state.map((_, i) =>
state.reduce((acc, a, j) => F.add(acc, F.mul(M[j][i], a)), F.zero)
);
}
state = state.map(a => pow5(a));
state = state.map((_, i) =>
state.reduce((acc, a, j) => F.add(acc, F.mul(M[j][i], a)), F.zero)
);
return state[0];
}
poseidon.F = F;
return poseidon;
}