package zk
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import (
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"crypto/rand"
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"fmt"
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"math/big"
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"github.com/arnaucube/go-snark/bn128"
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)
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const bits = 512
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func GenerateTrustedSetup(bn bn128.Bn128, pollength int) ([][3]*big.Int, [][3][2]*big.Int, error) {
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// generate random t value
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t, err := rand.Prime(rand.Reader, bits)
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if err != nil {
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return [][3]*big.Int{}, [][3][2]*big.Int{}, err
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}
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fmt.Print("trusted t: ")
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fmt.Println(t)
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// encrypt t values with curve generators
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var gt1 [][3]*big.Int
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var gt2 [][3][2]*big.Int
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for i := 0; i < pollength; i++ {
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tPow := bn.Fq1.Exp(t, big.NewInt(int64(i)))
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tEncr1 := bn.G1.MulScalar(bn.G1.G, tPow)
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gt1 = append(gt1, tEncr1)
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tEncr2 := bn.G2.MulScalar(bn.G2.G, tPow)
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gt2 = append(gt2, tEncr2)
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}
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// gt1: g1, g1*t, g1*t^2, g1*t^3, ...
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// gt2: g2, g2*t, g2*t^2, ...
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return gt1, gt2, nil
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}
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func 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) {
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// multiply g1*A(x), g2*B(x), g1*C(x), g1*H(x)
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// g1*A(x)
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g1At := [3]*big.Int{bn.G1.F.Zero(), bn.G1.F.Zero(), bn.G1.F.Zero()}
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for i := 0; i < len(ax); i++ {
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m := bn.G1.MulScalar(gt1[i], ax[i])
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g1At = bn.G1.Add(g1At, m)
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}
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g2Bt := bn.Fq6.Zero()
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for i := 0; i < len(bx); i++ {
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m := bn.G2.MulScalar(gt2[i], bx[i])
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g2Bt = bn.G2.Add(g2Bt, m)
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}
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g1Ct := [3]*big.Int{bn.G1.F.Zero(), bn.G1.F.Zero(), bn.G1.F.Zero()}
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for i := 0; i < len(cx); i++ {
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m := bn.G1.MulScalar(gt1[i], cx[i])
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g1Ct = bn.G1.Add(g1Ct, m)
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}
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g1Ht := [3]*big.Int{bn.G1.F.Zero(), bn.G1.F.Zero(), bn.G1.F.Zero()}
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for i := 0; i < len(hx); i++ {
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m := bn.G1.MulScalar(gt1[i], hx[i])
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g1Ht = bn.G1.Add(g1Ht, m)
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}
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g2Zt := bn.Fq6.Zero()
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for i := 0; i < len(bx); i++ {
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m := bn.G2.MulScalar(gt2[i], zx[i])
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g2Zt = bn.G2.Add(g2Zt, m)
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}
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return g1At, g2Bt, g1Ct, g1Ht, g2Zt
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}
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