+++ /dev/null
-package ecmath
-
-import (
- "crypto/subtle"
-
- "github.com/vapor/crypto/ed25519/internal/edwards25519"
-)
-
-// Point is a point on the ed25519 curve.
-type Point edwards25519.ExtendedGroupElement
-
-// ZeroPoint is the zero point on the ed25519 curve (not the zero value of Point).
-var ZeroPoint Point
-
-// Add adds the points in x and y, storing the result in z and
-// returning that. Any or all of x, y, and z may be the same pointers.
-func (z *Point) Add(x, y *Point) *Point {
- var y2 edwards25519.CachedGroupElement
- (*edwards25519.ExtendedGroupElement)(y).ToCached(&y2)
-
- var z2 edwards25519.CompletedGroupElement
- edwards25519.GeAdd(&z2, (*edwards25519.ExtendedGroupElement)(x), &y2)
-
- z2.ToExtended((*edwards25519.ExtendedGroupElement)(z))
- return z
-}
-
-// Sub subtracts y from x, storing the result in z and
-// returning that. Any or all of x, y, and z may be the same pointers.
-func (z *Point) Sub(x, y *Point) *Point {
- var y2 edwards25519.CachedGroupElement
- (*edwards25519.ExtendedGroupElement)(y).ToCached(&y2)
-
- var z2 edwards25519.CompletedGroupElement
- edwards25519.GeSub(&z2, (*edwards25519.ExtendedGroupElement)(x), &y2)
-
- z2.ToExtended((*edwards25519.ExtendedGroupElement)(z))
- return z
-}
-
-// ScMul multiplies the EC point x by the scalar y, placing the result
-// in z and returning that. X and z may be the same pointer.
-func (z *Point) ScMul(x *Point, y *Scalar) *Point {
- return z.ScMulAdd(x, y, &Zero)
-}
-
-// ScMulBase multiplies the ed25519 base point by x and places the
-// result in z, returning that.
-func (z *Point) ScMulBase(x *Scalar) *Point {
- edwards25519.GeScalarMultBase((*edwards25519.ExtendedGroupElement)(z), (*[32]byte)(x))
- return z
-}
-
-// ScMulAdd computes xa+yB, where B is the ed25519 base point, and
-// places the result in z, returning that.
-func (z *Point) ScMulAdd(a *Point, x, y *Scalar) *Point {
- // TODO: replace with constant-time implementation to avoid
- // sidechannel attacks
-
- var p edwards25519.ProjectiveGroupElement
- edwards25519.GeDoubleScalarMultVartime(&p, (*[32]byte)(x), (*edwards25519.ExtendedGroupElement)(a), (*[32]byte)(y))
-
- var buf [32]byte
- p.ToBytes(&buf)
- // TODO(bobg): double-check that it's OK to ignore the return value
- // from ExtendedGroupElement.FromBytes here. (It's a bool indicating
- // that its input represented a legal value.)
- (*edwards25519.ExtendedGroupElement)(z).FromBytes(&buf)
- return z
-}
-
-func (z *Point) Encode() [32]byte {
- var e [32]byte
- (*edwards25519.ExtendedGroupElement)(z).ToBytes(&e)
- return e
-}
-
-func (z *Point) Decode(e [32]byte) (*Point, bool) {
- ok := (*edwards25519.ExtendedGroupElement)(z).FromBytes(&e)
- return z, ok
-}
-
-func (z *Point) ConstTimeEqual(x *Point) bool {
- xe := x.Encode()
- ze := z.Encode()
- return subtle.ConstantTimeCompare(xe[:], ze[:]) == 1
-}
-
-func init() {
- (*edwards25519.ExtendedGroupElement)(&ZeroPoint).Zero()
-}