81 lines
3.0 KiB
JavaScript
81 lines
3.0 KiB
JavaScript
const assert = require("assert");
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const Scalar = require("ffjavascript").Scalar;
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const ZqField = require("ffjavascript").ZqField;
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const { unstringifyBigInts } = require("ffjavascript").utils;
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// const F = new ZqField(Scalar.fromString("0x73eda753299d7d483339d80809a1d80553bda402fffe5bfeffffffff00000001")); // bls
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const F = new ZqField(Scalar.fromString("21888242871839275222246405745257275088548364400416034343698204186575808495617")); // bn128
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// Parameters are generated by a reference script https://extgit.iaik.tugraz.at/krypto/hadeshash/-/blob/master/code/generate_parameters_grain.sage
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// Used like so: sage generate_parameters_grain.sage 1 0 254 2 8 56 0x30644e72e131a029b85045b68181585d2833e84879b9709143e1f593f0000001
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const opt = unstringifyBigInts(require("./poseidon_constants_opt.json"));
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// Using recommended parameters from whitepaper https://eprint.iacr.org/2019/458.pdf (table 2, table 8)
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// Generated by https://extgit.iaik.tugraz.at/krypto/hadeshash/-/blob/master/code/calc_round_numbers.py
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// And rounded up to nearest integer that divides by t
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const N_ROUNDS_F = 8;
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const N_ROUNDS_P = [56, 57, 56, 60, 60, 63, 64, 63, 60, 66, 60, 65, 70, 60, 64, 68];
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const pow5 = a => F.mul(a, F.square(F.square(a, a)));
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function poseidon(inputs) {
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assert(inputs.length > 0);
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assert(inputs.length < N_ROUNDS_P.length - 1);
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const t = inputs.length + 1;
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const nRoundsF = N_ROUNDS_F;
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const nRoundsP = N_ROUNDS_P[t - 2];
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const C = opt.C[t-2];
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const S = opt.S[t-2];
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const M = opt.M[t-2];
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const P = opt.P[t-2];
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let state = [F.zero, ...inputs.map(a => F.e(a))];
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state = state.map((a, i) => F.add(a, C[i]));
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for (let r = 0; r < nRoundsF/2-1; r++) {
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state = state.map(a => pow5(a));
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state = state.map((a, i) => F.add(a, C[(r +1)* t +i]));
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state = state.map((_, i) =>
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state.reduce((acc, a, j) => F.add(acc, F.mul(M[j][i], a)), F.zero)
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);
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}
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state = state.map(a => pow5(a));
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state = state.map((a, i) => F.add(a, C[(nRoundsF/2-1 +1)* t +i]));
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state = state.map((_, i) =>
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state.reduce((acc, a, j) => F.add(acc, F.mul(P[j][i], a)), F.zero)
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);
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for (let r = 0; r < nRoundsP; r++) {
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state[0] = pow5(state[0]);
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state[0] = F.add(state[0], C[(nRoundsF/2 +1)*t + r]);
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const s0 = state.reduce((acc, a, j) => {
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return F.add(acc, F.mul(S[(t*2-1)*r+j], a));
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}, F.zero);
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for (let k=1; k<t; k++) {
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state[k] = F.add(state[k], F.mul(state[0], S[(t*2-1)*r+t+k-1] ));
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}
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state[0] =s0;
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}
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for (let r = 0; r < nRoundsF/2-1; r++) {
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state = state.map(a => pow5(a));
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state = state.map((a, i) => F.add(a, C[ (nRoundsF/2 +1)*t + nRoundsP + r*t + i ]));
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state = state.map((_, i) =>
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state.reduce((acc, a, j) => F.add(acc, F.mul(M[j][i], a)), F.zero)
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);
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}
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state = state.map(a => pow5(a));
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state = state.map((_, i) =>
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state.reduce((acc, a, j) => F.add(acc, F.mul(M[j][i], a)), F.zero)
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);
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return F.normalize(state[0]);
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}
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module.exports = poseidon;
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