snarkjs/src/g1curve.js
src/g1curve.jsRaw
1const bigInt = require("big-integer");
2
3const q = new bigInt("21888242871839275222246405745257275088696311157297823662689037894645226208583");
4
5module.eports = class G1Curve {
6
7 constructor() {
8 this.g = [ bigInt(1), bigInt(2), bigInt(1) ];
9 this.zero = [ bigInt(0), bigInt(1), bigInt(0) ];
10 }
11
12 isZero(p) {
13 return p[2].isZero();
14 }
15 add(p1, p2) {
16
17 if (this.isZero(p1)) return p2;
18 if (this.isZero(p2)) return p1;
19
20 const res = new Array(3);
21
22 const Z1Z1 = p1[2].square().mod(q);
23 const Z2Z2 = p2[2].square().mod(q);
24
25 const U1 = p1[0].times(Z2Z2).mod(q);
26 const U2 = p2[0].times(Z1Z1).mod(q);
27
28 const Z1_cubed = p1[2].times(Z1Z1).mod(q);
29 const Z2_cubed = p2[2].times(Z2Z2).mod(q);
30
31 const S1 = p1[1].times(Z2_cubed).mod(q);
32 const S2 = p2[1].times(Z1_cubed).mod(q);
33
34 if (U1.equals(U2) && (S1.equals(S2))) {
35 return this.double(p1);
36 }
37
38 let H = U2.minus(U1);
39 if (H.isNegative()) H = H.add(q);
40
41 let S2_minus_S1 = S2.minus(S1);
42 if (S2_minus_S1.isNegative()) S2_minus_S1 = S2_minus_S1.add(q);
43
44 const I = H.add(H).square().mod(q);
45 const J = H.times(I).mod(q);
46
47 const r = S2_minus_S1.add(S2_minus_S1);
48 const V = U1.times(I).mod(q);
49
50 res[0] = r.square().minus(J).minus(V).minus(V).mod(q);
51 if (res[0].isNegative()) res[0] = res[0].add(q);
52
53 const S1_J = S1.times(J).mod(q);
54
55 res[1] = r.times(V.minus(res[0])).minus(S1_J).minus(S1_J).mod(q);
56 if (res[1].isNegative()) res[1] = res[1].add(q);
57
58 res[2] = p1[2].add(p2[2]).square().minus(Z1Z1).minus(Z2Z2).mod(q);
59 res[2] = res[2].times(H).mod(q);
60 if (res[2].isNegative()) res[2] = res[2].add(q);
61
62 return res;
63 }
64
65 double(p) {
66 const res = new Array(3);
67
68 if (this.isZero(p)) return p;
69
70 const A = p[0].square().mod(q);
71 const B = p[1].square().mod(q);
72 const C = B.square().mod(q);
73
74 let D = p[0].add(B).square().minus(A).minus(C);
75 D = D.add(D);
76
77 const E = A.times(3);
78 const F = E.square();
79
80 res[0] = F.minus(D).minus(D).mod(q);
81 if (res[0].isNegative()) res[0] = res[0].add(q);
82
83 const eightC = C.times(8);
84
85 res[1] = E.times(D.minus(res[0])).minus(eightC).mod(q);
86 if (res[1].isNegative()) res[1] = res[1].add(q);
87
88 const Y1Z1 = p[1].times(p[2]);
89 res[2] = Y1Z1.add(Y1Z1).mod(q);
90
91 return res;
92 }
93
94 toAffineCoordinates(p) {
95 if (this.isZero(p)) {
96 return this.zero;
97 } else {
98 const Z_inv = p[2].modInv(q);
99 const Z2_inv = Z_inv.square().mod(q);
100 const Z3_inv = Z2_inv.times(Z_inv).mod(q);
101
102 const res = new Array(3);
103 res[0] = p[0].times(Z2_inv).mod(q);
104 res[1] = p[1].times(Z3_inv).mod(q);
105 res[2] = bigInt(1);
106
107 return res;
108 }
109 }
110
111 mulEscalar(base, e) {
112 let res = this.zero;
113 let rem = e;
114 let exp = base;
115
116 while (! rem.isZero()) {
117 if (rem.isOdd()) {
118 res = this.add(res, exp);
119 }
120 exp = this.double(exp);
121 rem = rem.shiftRight(1);
122 }
123
124 return res;
125 }
126
127};
128
129const G1 = new module.eports();
130
131
132const r = bigInt("21888242871839275222246405745257275088548364400416034343698204186575808495617");
133// const np = G1.mulEscalar(G1.g, bigInt(2));
134
135const np = G1.mulEscalar(G1.g, r.add(1));
136const p = G1.toAffineCoordinates(np);
137
138/*
139const np2 = G1.add(G1.g, G1.g);
140const np3 = G1.add(G1.g, np2);
141
142const p = G1.toAffineCoordinates(np3);
143*/
144
145console.log(p[0].toString() + ", " + p[1].toString() + ", " + p[2].toString());
146
147