84 lines
1.7 KiB
JavaScript
84 lines
1.7 KiB
JavaScript
const bn128 = require("snarkjs").bn128;
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const bigInt = require("snarkjs").bigInt;
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const createBlakeHash = require("blake-hash");
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const babyJub = require("../src/babyjub");
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function getPoint(S) {
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const F = bn128.Fr;
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const h = createBlakeHash("blake256").update(S).digest();
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if (h.length != 32) {
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throw new Error("Invalid length")
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}
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let sign = false;
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if (h[31] & 0x80) {
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h[31] = h[31] & 0x7F;
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sign = true;
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}
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let y = bigInt(0);
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for (let i=0; i<32; i++) {
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y = y.shl(8);
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y = y.add(bigInt(h[i]));
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}
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const a = bigInt("168700");
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const d = bigInt("168696");
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const y2 = F.square(y);
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let x = F.sqrt(F.div(
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F.sub(F.one, y2),
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F.sub(a, F.mul(d, y2))));
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if (x == null) return null;
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if (sign) x = F.neg(x);
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const p = [bn128.Fr.affine(x), bn128.Fr.affine(y)];
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const p8 = babyJub.mulPointEscalar(p, 8);
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return p8;
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}
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function generatePoint(S) {
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let p= null;
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let idx = 0;
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while (p==null) {
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let sidx = "" + idx;
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while (sidx.length<16) sidx = "0"+sidx;
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p = getPoint(S+"_"+sidx);
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idx++;
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}
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if (!babyJub.inCurve(p)){
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throw new Error("Point not in curve");
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}
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return p;
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}
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const g = [
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bigInt("5299619240641551281634865583518297030282874472190772894086521144482721001553"),
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bigInt("16950150798460657717958625567821834550301663161624707787222815936182638968203")];
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// Sanity check
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if (!babyJub.inCurve(g)) {
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throw new Error("Generator not In curve -> Some thing goes wrong...");
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}
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for (let i=0; i<25; i++) {
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let S = "" +i;
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while (S.length<16) S = "0"+S;
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const P = generatePoint("Iden3_PedersenGenerator_"+S);
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console.log(`[${P[0].toString()}, ${P[1].toString()}]`);
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}
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