1const bn128 = require("snarkjs").bn128;
 2const bigInt = require("snarkjs").bigInt;
 3const createBlakeHash = require("blake-hash");
 4const babyJub = require("../src/babyjub");
 5
 6function getPoint(S) {
 7    const F = bn128.Fr;
 8    const h = createBlakeHash("blake256").update(S).digest();
 9
10    if (h.length != 32) {
11        throw new Error("Invalid length")
12    }
13
14    let sign = false;
15    if (h[31] & 0x80) {
16        h[31] = h[31] & 0x7F;
17        sign = true;
18    }
19
20    let y = bigInt(0);
21    for (let i=0; i<32; i++) {
22        y = y.shl(8);
23        y = y.add(bigInt(h[i]));
24    }
25
26    const a = bigInt("168700");
27    const d = bigInt("168696");
28
29    const y2 = F.square(y);
30
31    let x = F.sqrt(F.div(
32        F.sub(F.one, y2),
33        F.sub(a, F.mul(d, y2))));
34
35    if (x == null) return null;
36
37    if (sign) x = F.neg(x);
38
39    const p = [bn128.Fr.affine(x), bn128.Fr.affine(y)];
40
41    const p8 = babyJub.mulPointEscalar(p, 8);
42
43    return p8;
44}
45
46
47function generatePoint(S) {
48    let p= null;
49    let idx = 0;
50    while (p==null) {
51        let sidx = "" + idx;
52        while (sidx.length<16) sidx = "0"+sidx;
53        p = getPoint(S+"_"+sidx);
54        idx++;
55    }
56    if (!babyJub.inCurve(p)){
57        throw new Error("Point not in curve");
58    }
59    return p;
60}
61
62
63
64
65
66const g = [
67    bigInt("5299619240641551281634865583518297030282874472190772894086521144482721001553"),
68    bigInt("16950150798460657717958625567821834550301663161624707787222815936182638968203")];
69
70// Sanity check
71if (!babyJub.inCurve(g)) {
72    throw new Error("Generator not In curve -> Some thing goes wrong...");
73}
74
75for (let i=0; i<25; i++) {
76    let S = "" +i;
77    while (S.length<16) S = "0"+S;
78    const P = generatePoint("Iden3_PedersenGenerator_"+S);
79    console.log(`[${P[0].toString()}, ${P[1].toString()}]`);
80}
81
82
83