crypto/secp256k1: change receiver variable name to lowercase (#29889)
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@ -79,52 +79,52 @@ type BitCurve struct {
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BitSize int // the size of the underlying field
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}
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func (BitCurve *BitCurve) Params() *elliptic.CurveParams {
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func (bitCurve *BitCurve) Params() *elliptic.CurveParams {
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return &elliptic.CurveParams{
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P: BitCurve.P,
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N: BitCurve.N,
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B: BitCurve.B,
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Gx: BitCurve.Gx,
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Gy: BitCurve.Gy,
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BitSize: BitCurve.BitSize,
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P: bitCurve.P,
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N: bitCurve.N,
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B: bitCurve.B,
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Gx: bitCurve.Gx,
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Gy: bitCurve.Gy,
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BitSize: bitCurve.BitSize,
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}
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}
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// IsOnCurve returns true if the given (x,y) lies on the BitCurve.
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func (BitCurve *BitCurve) IsOnCurve(x, y *big.Int) bool {
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func (bitCurve *BitCurve) IsOnCurve(x, y *big.Int) bool {
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// y² = x³ + b
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y2 := new(big.Int).Mul(y, y) //y²
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y2.Mod(y2, BitCurve.P) //y²%P
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y2.Mod(y2, bitCurve.P) //y²%P
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x3 := new(big.Int).Mul(x, x) //x²
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x3.Mul(x3, x) //x³
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x3.Add(x3, BitCurve.B) //x³+B
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x3.Mod(x3, BitCurve.P) //(x³+B)%P
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x3.Add(x3, bitCurve.B) //x³+B
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x3.Mod(x3, bitCurve.P) //(x³+B)%P
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return x3.Cmp(y2) == 0
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}
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// affineFromJacobian reverses the Jacobian transform. See the comment at the
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// top of the file.
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func (BitCurve *BitCurve) affineFromJacobian(x, y, z *big.Int) (xOut, yOut *big.Int) {
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func (bitCurve *BitCurve) affineFromJacobian(x, y, z *big.Int) (xOut, yOut *big.Int) {
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if z.Sign() == 0 {
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return new(big.Int), new(big.Int)
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}
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zinv := new(big.Int).ModInverse(z, BitCurve.P)
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zinv := new(big.Int).ModInverse(z, bitCurve.P)
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zinvsq := new(big.Int).Mul(zinv, zinv)
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xOut = new(big.Int).Mul(x, zinvsq)
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xOut.Mod(xOut, BitCurve.P)
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xOut.Mod(xOut, bitCurve.P)
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zinvsq.Mul(zinvsq, zinv)
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yOut = new(big.Int).Mul(y, zinvsq)
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yOut.Mod(yOut, BitCurve.P)
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yOut.Mod(yOut, bitCurve.P)
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return
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}
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// Add returns the sum of (x1,y1) and (x2,y2)
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func (BitCurve *BitCurve) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int) {
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func (bitCurve *BitCurve) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int) {
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// If one point is at infinity, return the other point.
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// Adding the point at infinity to any point will preserve the other point.
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if x1.Sign() == 0 && y1.Sign() == 0 {
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@ -135,27 +135,27 @@ func (BitCurve *BitCurve) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int) {
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}
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z := new(big.Int).SetInt64(1)
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if x1.Cmp(x2) == 0 && y1.Cmp(y2) == 0 {
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return BitCurve.affineFromJacobian(BitCurve.doubleJacobian(x1, y1, z))
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return bitCurve.affineFromJacobian(bitCurve.doubleJacobian(x1, y1, z))
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}
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return BitCurve.affineFromJacobian(BitCurve.addJacobian(x1, y1, z, x2, y2, z))
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return bitCurve.affineFromJacobian(bitCurve.addJacobian(x1, y1, z, x2, y2, z))
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}
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// addJacobian takes two points in Jacobian coordinates, (x1, y1, z1) and
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// (x2, y2, z2) and returns their sum, also in Jacobian form.
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func (BitCurve *BitCurve) addJacobian(x1, y1, z1, x2, y2, z2 *big.Int) (*big.Int, *big.Int, *big.Int) {
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func (bitCurve *BitCurve) addJacobian(x1, y1, z1, x2, y2, z2 *big.Int) (*big.Int, *big.Int, *big.Int) {
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// See http://hyperelliptic.org/EFD/g1p/auto-shortw-jacobian-0.html#addition-add-2007-bl
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z1z1 := new(big.Int).Mul(z1, z1)
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z1z1.Mod(z1z1, BitCurve.P)
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z1z1.Mod(z1z1, bitCurve.P)
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z2z2 := new(big.Int).Mul(z2, z2)
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z2z2.Mod(z2z2, BitCurve.P)
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z2z2.Mod(z2z2, bitCurve.P)
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u1 := new(big.Int).Mul(x1, z2z2)
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u1.Mod(u1, BitCurve.P)
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u1.Mod(u1, bitCurve.P)
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u2 := new(big.Int).Mul(x2, z1z1)
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u2.Mod(u2, BitCurve.P)
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u2.Mod(u2, bitCurve.P)
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h := new(big.Int).Sub(u2, u1)
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if h.Sign() == -1 {
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h.Add(h, BitCurve.P)
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h.Add(h, bitCurve.P)
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}
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i := new(big.Int).Lsh(h, 1)
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i.Mul(i, i)
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@ -163,13 +163,13 @@ func (BitCurve *BitCurve) addJacobian(x1, y1, z1, x2, y2, z2 *big.Int) (*big.Int
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s1 := new(big.Int).Mul(y1, z2)
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s1.Mul(s1, z2z2)
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s1.Mod(s1, BitCurve.P)
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s1.Mod(s1, bitCurve.P)
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s2 := new(big.Int).Mul(y2, z1)
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s2.Mul(s2, z1z1)
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s2.Mod(s2, BitCurve.P)
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s2.Mod(s2, bitCurve.P)
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r := new(big.Int).Sub(s2, s1)
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if r.Sign() == -1 {
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r.Add(r, BitCurve.P)
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r.Add(r, bitCurve.P)
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}
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r.Lsh(r, 1)
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v := new(big.Int).Mul(u1, i)
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@ -179,7 +179,7 @@ func (BitCurve *BitCurve) addJacobian(x1, y1, z1, x2, y2, z2 *big.Int) (*big.Int
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x3.Sub(x3, j)
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x3.Sub(x3, v)
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x3.Sub(x3, v)
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x3.Mod(x3, BitCurve.P)
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x3.Mod(x3, bitCurve.P)
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y3 := new(big.Int).Set(r)
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v.Sub(v, x3)
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@ -187,33 +187,33 @@ func (BitCurve *BitCurve) addJacobian(x1, y1, z1, x2, y2, z2 *big.Int) (*big.Int
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s1.Mul(s1, j)
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s1.Lsh(s1, 1)
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y3.Sub(y3, s1)
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y3.Mod(y3, BitCurve.P)
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y3.Mod(y3, bitCurve.P)
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z3 := new(big.Int).Add(z1, z2)
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z3.Mul(z3, z3)
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z3.Sub(z3, z1z1)
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if z3.Sign() == -1 {
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z3.Add(z3, BitCurve.P)
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z3.Add(z3, bitCurve.P)
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}
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z3.Sub(z3, z2z2)
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if z3.Sign() == -1 {
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z3.Add(z3, BitCurve.P)
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z3.Add(z3, bitCurve.P)
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}
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z3.Mul(z3, h)
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z3.Mod(z3, BitCurve.P)
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z3.Mod(z3, bitCurve.P)
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return x3, y3, z3
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}
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// Double returns 2*(x,y)
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func (BitCurve *BitCurve) Double(x1, y1 *big.Int) (*big.Int, *big.Int) {
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func (bitCurve *BitCurve) Double(x1, y1 *big.Int) (*big.Int, *big.Int) {
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z1 := new(big.Int).SetInt64(1)
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return BitCurve.affineFromJacobian(BitCurve.doubleJacobian(x1, y1, z1))
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return bitCurve.affineFromJacobian(bitCurve.doubleJacobian(x1, y1, z1))
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}
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// doubleJacobian takes a point in Jacobian coordinates, (x, y, z), and
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// returns its double, also in Jacobian form.
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func (BitCurve *BitCurve) doubleJacobian(x, y, z *big.Int) (*big.Int, *big.Int, *big.Int) {
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func (bitCurve *BitCurve) doubleJacobian(x, y, z *big.Int) (*big.Int, *big.Int, *big.Int) {
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// See http://hyperelliptic.org/EFD/g1p/auto-shortw-jacobian-0.html#doubling-dbl-2009-l
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a := new(big.Int).Mul(x, x) //X1²
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@ -231,30 +231,30 @@ func (BitCurve *BitCurve) doubleJacobian(x, y, z *big.Int) (*big.Int, *big.Int,
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x3 := new(big.Int).Mul(big.NewInt(2), d) //2*D
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x3.Sub(f, x3) //F-2*D
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x3.Mod(x3, BitCurve.P)
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x3.Mod(x3, bitCurve.P)
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y3 := new(big.Int).Sub(d, x3) //D-X3
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y3.Mul(e, y3) //E*(D-X3)
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y3.Sub(y3, new(big.Int).Mul(big.NewInt(8), c)) //E*(D-X3)-8*C
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y3.Mod(y3, BitCurve.P)
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y3.Mod(y3, bitCurve.P)
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z3 := new(big.Int).Mul(y, z) //Y1*Z1
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z3.Mul(big.NewInt(2), z3) //3*Y1*Z1
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z3.Mod(z3, BitCurve.P)
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z3.Mod(z3, bitCurve.P)
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return x3, y3, z3
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}
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// ScalarBaseMult returns k*G, where G is the base point of the group and k is
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// an integer in big-endian form.
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func (BitCurve *BitCurve) ScalarBaseMult(k []byte) (*big.Int, *big.Int) {
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return BitCurve.ScalarMult(BitCurve.Gx, BitCurve.Gy, k)
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func (bitCurve *BitCurve) ScalarBaseMult(k []byte) (*big.Int, *big.Int) {
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return bitCurve.ScalarMult(bitCurve.Gx, bitCurve.Gy, k)
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}
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// Marshal converts a point into the form specified in section 4.3.6 of ANSI
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// X9.62.
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func (BitCurve *BitCurve) Marshal(x, y *big.Int) []byte {
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byteLen := (BitCurve.BitSize + 7) >> 3
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func (bitCurve *BitCurve) Marshal(x, y *big.Int) []byte {
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byteLen := (bitCurve.BitSize + 7) >> 3
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ret := make([]byte, 1+2*byteLen)
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ret[0] = 4 // uncompressed point flag
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readBits(x, ret[1:1+byteLen])
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@ -264,8 +264,8 @@ func (BitCurve *BitCurve) Marshal(x, y *big.Int) []byte {
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// Unmarshal converts a point, serialised by Marshal, into an x, y pair. On
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// error, x = nil.
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func (BitCurve *BitCurve) Unmarshal(data []byte) (x, y *big.Int) {
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byteLen := (BitCurve.BitSize + 7) >> 3
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func (bitCurve *BitCurve) Unmarshal(data []byte) (x, y *big.Int) {
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byteLen := (bitCurve.BitSize + 7) >> 3
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if len(data) != 1+2*byteLen {
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return
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}
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@ -21,7 +21,7 @@ extern int secp256k1_ext_scalar_mul(const secp256k1_context* ctx, const unsigned
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*/
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import "C"
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func (BitCurve *BitCurve) ScalarMult(Bx, By *big.Int, scalar []byte) (*big.Int, *big.Int) {
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func (bitCurve *BitCurve) ScalarMult(Bx, By *big.Int, scalar []byte) (*big.Int, *big.Int) {
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// Ensure scalar is exactly 32 bytes. We pad always, even if
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// scalar is 32 bytes long, to avoid a timing side channel.
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if len(scalar) > 32 {
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@ -9,6 +9,6 @@ package secp256k1
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import "math/big"
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func (BitCurve *BitCurve) ScalarMult(Bx, By *big.Int, scalar []byte) (*big.Int, *big.Int) {
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func (bitCurve *BitCurve) ScalarMult(Bx, By *big.Int, scalar []byte) (*big.Int, *big.Int) {
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panic("ScalarMult is not available when secp256k1 is built without cgo")
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}
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