1const bn128 = require("snarkjs").bn128;
 2const bigInt = require("snarkjs").bigInt;
 3const createBlakeHash = require("blake-hash");
 4const assert = require("assert");
 5
 6function getPoint(S) {
 7    const F = bn128.Fr;
 8    const h = createBlakeHash("blake256").update(S).digest();
 9
10    assert(h.length == 32);
11
12    let sign = false;
13    if (h[31] & 0x80) {
14        h[31] = h[31] & 0x7F;
15        sign = true;
16    }
17
18    let x = bigInt(0);
19    for (let i=0; i<32; i++) {
20        x = x.shl(8);
21        x = x.add(bigInt(h[i]));
22    }
23
24    const a = bigInt("168700");
25    const d = bigInt("168696");
26
27    const x2 = F.square(x);
28
29    let y = F.sqrt(F.div(
30        F.sub(F.one, F.mul(a, x2)),
31        F.sub(F.one, F.mul(d, x2))));
32
33    if (y == null) return null;
34
35    if (sign) y = F.neg(y);
36
37    return [bn128.Fr.affine(x), bn128.Fr.affine(y)];
38}
39
40
41function generatePoint(S) {
42    let p= null;
43    let idx = 0;
44    while (p==null) {
45        let sidx = "" + idx;
46        while (sidx.length<16) sidx = "0"+sidx;
47        p = getPoint(S+"_"+sidx);
48        idx++;
49    }
50    assert(inCurve(p));
51    return p;
52}
53
54function inCurve(p) {
55    const F = bn128.Fr;
56
57    const a = bigInt("168700");
58    const d = bigInt("168696");
59
60    const x2 = F.square(p[0]);
61    const y2 = F.square(p[1]);
62
63    return F.equals(
64        F.add(F.mul(a, x2), y2),
65        F.add(F.one, F.mul(F.mul(x2, y2), d)));
66}
67
68const g = [
69    bigInt("17777552123799933955779906779655732241715742912184938656739573121738514868268"),
70    bigInt("2626589144620713026669568689430873010625803728049924121243784502389097019475")];
71
72if (!inCurve(g)) {
73    throw new Error("Generator not In curve -> Some thing goes wrong...");
74}
75
76for (let i=0; i<25; i++) {
77    let S = "" +i;
78    while (S.length<16) S = "0"+S;
79    const P = generatePoint("Iden3_PedersenGenerator_"+S);
80    console.log(`[${P[0].toString()}, ${P[1].toString()}]`);
81}
82
83
84