1package zk
 2
 3import (
 4	"crypto/rand"
 5	"fmt"
 6	"math/big"
 7
 8	"github.com/arnaucube/go-snark/bn128"
 9)
10
11const bits = 512
12
13func GenerateTrustedSetup(bn bn128.Bn128, pollength int) ([][3]*big.Int, [][3][2]*big.Int, error) {
14	// generate random t value
15	t, err := rand.Prime(rand.Reader, bits)
16	if err != nil {
17		return [][3]*big.Int{}, [][3][2]*big.Int{}, err
18	}
19	fmt.Print("trusted t: ")
20	fmt.Println(t)
21
22	// encrypt t values with curve generators
23	var gt1 [][3]*big.Int
24	var gt2 [][3][2]*big.Int
25	for i := 0; i < pollength; i++ {
26		tPow := bn.Fq1.Exp(t, big.NewInt(int64(i)))
27		tEncr1 := bn.G1.MulScalar(bn.G1.G, tPow)
28		gt1 = append(gt1, tEncr1)
29		tEncr2 := bn.G2.MulScalar(bn.G2.G, tPow)
30		gt2 = append(gt2, tEncr2)
31	}
32	// gt1: g1, g1*t, g1*t^2, g1*t^3, ...
33	// gt2: g2, g2*t, g2*t^2, ...
34	return gt1, gt2, nil
35}
36func GenerateProofs(bn bn128.Bn128, gt1 [][3]*big.Int, gt2 [][3][2]*big.Int, ax, bx, cx, hx, zx []*big.Int) ([3]*big.Int, [3][2]*big.Int, [3]*big.Int, [3]*big.Int, [3][2]*big.Int) {
37
38	// multiply g1*A(x), g2*B(x), g1*C(x), g1*H(x)
39
40	// g1*A(x)
41	g1At := [3]*big.Int{bn.G1.F.Zero(), bn.G1.F.Zero(), bn.G1.F.Zero()}
42	for i := 0; i < len(ax); i++ {
43		m := bn.G1.MulScalar(gt1[i], ax[i])
44		g1At = bn.G1.Add(g1At, m)
45	}
46	g2Bt := bn.Fq6.Zero()
47	for i := 0; i < len(bx); i++ {
48		m := bn.G2.MulScalar(gt2[i], bx[i])
49		g2Bt = bn.G2.Add(g2Bt, m)
50	}
51
52	g1Ct := [3]*big.Int{bn.G1.F.Zero(), bn.G1.F.Zero(), bn.G1.F.Zero()}
53	for i := 0; i < len(cx); i++ {
54		m := bn.G1.MulScalar(gt1[i], cx[i])
55		g1Ct = bn.G1.Add(g1Ct, m)
56	}
57	g1Ht := [3]*big.Int{bn.G1.F.Zero(), bn.G1.F.Zero(), bn.G1.F.Zero()}
58	for i := 0; i < len(hx); i++ {
59		m := bn.G1.MulScalar(gt1[i], hx[i])
60		g1Ht = bn.G1.Add(g1Ht, m)
61	}
62	g2Zt := bn.Fq6.Zero()
63	for i := 0; i < len(bx); i++ {
64		m := bn.G2.MulScalar(gt2[i], zx[i])
65		g2Zt = bn.G2.Add(g2Zt, m)
66	}
67
68	return g1At, g2Bt, g1Ct, g1Ht, g2Zt
69}