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New method to calculate polinomial H in groth

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Jordi Baylina 2020-04-05 20:09:21 +02:00
parent b5e03d492a
commit eb0a87e548
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src/prover_groth.js
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@ -105,6 +105,8 @@ module.exports = function genProof(vk_proof, witness) {
};
/*
// Old Method. (It's clear for academic understanding)
function calculateH(vk_proof, witness) {
const F = PolF.F;
@ -120,9 +122,11 @@ function calculateH(vk_proof, witness) {
for (let c in vk_proof.polsB[s]) {
polB_T[c] = F.add(polB_T[c], F.mul(witness[s], vk_proof.polsB[s][c]));
}
for (let c in vk_proof.polsC[s]) {
polC_T[c] = F.add(polC_T[c], F.mul(witness[s], vk_proof.polsC[s][c]));
}
}
const polA_S = PolF.ifft(polA_T);
@ -138,3 +142,49 @@ function calculateH(vk_proof, witness) {
return H_S;
}
*/
function calculateH(vk_proof, witness) {
const F = PolF.F;
const m = vk_proof.domainSize;
const polA_T = new Array(m).fill(PolF.F.zero);
const polB_T = new Array(m).fill(PolF.F.zero);
for (let s=0; s<vk_proof.nVars; s++) {
for (let c in vk_proof.polsA[s]) {
polA_T[c] = F.add(polA_T[c], F.mul(witness[s], vk_proof.polsA[s][c]));
}
for (let c in vk_proof.polsB[s]) {
polB_T[c] = F.add(polB_T[c], F.mul(witness[s], vk_proof.polsB[s][c]));
}
}
const polA_S = PolF.ifft(polA_T);
const polB_S = PolF.ifft(polB_T);
// F(wx) = [1, w, w^2, ...... w^(m-1)] in time is the same than shift in in frequency
const r = PolF.log2(m)+1;
PolF._setRoots(r);
for (let i=0; i<polA_S.length; i++) {
polA_S[i] = PolF.F.mul( polA_S[i], PolF.roots[r][i]);
polB_S[i] = PolF.F.mul( polB_S[i], PolF.roots[r][i]);
}
const polA_Todd = PolF.fft(polA_S);
const polB_Todd = PolF.fft(polB_S);
const polAB_T = new Array(polA_S.length*2);
for (let i=0; i<polA_S.length; i++) {
polAB_T[2*i] = PolF.F.mul( polA_T[i], polB_T[i]);
polAB_T[2*i+1] = PolF.F.mul( polA_Todd[i], polB_Todd[i]);
}
// We only need the to half of the fft, so we could optimize at least by m multiplications.
let H_S = PolF.ifft(polAB_T);
H_S = H_S.slice(m);
return H_S;
}