本文整理汇总了Golang中github.com/decred/ed25519/edwards25519.ExtendedGroupElement.Double方法的典型用法代码示例。如果您正苦于以下问题：Golang ExtendedGroupElement.Double方法的具体用法？Golang ExtendedGroupElement.Double怎么用？Golang ExtendedGroupElement.Double使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类github.com/decred/ed25519/edwards25519.ExtendedGroupElement的用法示例。
在下文中一共展示了ExtendedGroupElement.Double方法的2个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的Golang代码示例。
示例1: ScalarMult
// ScalarMult returns k*(Bx,By) where k is a number in big-endian form. This
// uses the repeated doubling method, which is variable time.
// TODO use a constant time method to prevent side channel attacks.
func (curve *TwistedEdwardsCurve) ScalarMult(x1, y1 *big.Int,
k []byte) (x, y *big.Int) {
// Convert the scalar to a big int.
s := new(big.Int).SetBytes(k)
// Get a new group element to do cached doubling
// calculations in.
dEGE := new(edwards25519.ExtendedGroupElement)
dEGE.Zero()
// Use the doubling method for the multiplication.
// p := given point
// q := point(zero)
// for each bit in the scalar, descending:
// double(q)
// if bit == 1:
// add(q, p)
// return q
//
// Note that the addition is skipped for zero bits,
// making this variable time and thus vulnerable to
// side channel attack vectors.
for i := s.BitLen() - 1; i >= 0; i-- {
dCGE := new(edwards25519.CompletedGroupElement)
dEGE.Double(dCGE)
dCGE.ToExtended(dEGE)
if s.Bit(i) == 1 {
ss := new([32]byte)
dEGE.ToBytes(ss)
var err error
xi, yi, err := curve.EncodedBytesToBigIntPoint(ss)
if err != nil {
return nil, nil
}
xAdd, yAdd := curve.Add(xi, yi, x1, y1)
dTempBytes := BigIntPointToEncodedBytes(xAdd, yAdd)
dEGE.FromBytes(dTempBytes)
}
}
finalBytes := new([32]byte)
dEGE.ToBytes(finalBytes)
var err error
x, y, err = curve.EncodedBytesToBigIntPoint(finalBytes)
if err != nil {
return nil, nil
}
return
}示例2: Double
// Double adds the same pair of big integer coordinates to itself on the
// elliptical curve.
func (curve *TwistedEdwardsCurve) Double(x1, y1 *big.Int) (x, y *big.Int) {
// Convert to extended projective coordinates.
a := BigIntPointToEncodedBytes(x1, y1)
aEGE := new(edwards25519.ExtendedGroupElement)
aEGE.FromBytes(a)
r := new(edwards25519.CompletedGroupElement)
aEGE.Double(r)
rEGE := new(edwards25519.ExtendedGroupElement)
r.ToExtended(rEGE)
s := new([32]byte)
rEGE.ToBytes(s)
x, y, _ = curve.EncodedBytesToBigIntPoint(s)
return
}