func (p *point) Mul(cb abstract.Point, cs abstract.Scalar) abstract.Point {
s := cs.(*scalar)
if cb == nil { // multiply standard generator
if C.EC_POINT_mul(p.c.g, p.p, s.bignum.bn, nil, nil,
p.c.ctx) == 0 {
panic("EC_POINT_mul: " + getErrString())
}
} else { // multiply arbitrary point b
b := cb.(*point)
if C.EC_POINT_mul(p.c.g, p.p, nil, b.p, s.bignum.bn,
p.c.ctx) == 0 {
panic("EC_POINT_mul: " + getErrString())
}
}
return p
}
func (curve CurveParams) ScalarMult(x1, y1 *big.Int, k []byte) (x, y *big.Int) {
bnx1 := C.BN_new()
if bnx1 == nil {
return nil, nil
}
defer C.BN_free(bnx1)
bny1 := C.BN_new()
if bny1 == nil {
return nil, nil
}
defer C.BN_free(bny1)
x1s := C.CString(x1.String())
defer C.free(unsafe.Pointer(x1s))
if C.BN_hex2bn(&bnx1, x1s) == 0 {
return nil, nil
}
y1s := C.CString(y1.String())
defer C.free(unsafe.Pointer(y1s))
if C.BN_hex2bn(&bny1, y1s) == 0 {
return nil, nil
}
pointR := C.EC_POINT_new(curve.curve)
if pointR == nil {
return nil, nil
}
defer C.EC_POINT_free(pointR)
pointQ := C.EC_POINT_new(curve.curve)
if pointQ == nil {
return nil, nil
}
defer C.EC_POINT_free(pointQ)
if C.EC_POINT_set_affine_coordinates_GFp(curve.curve, pointQ, bnx1, bny1, nil) != 1 {
return nil, nil
}
n := C.BN_new()
if n == nil {
return nil, nil
}
defer C.BN_free(n)
bn := C.CString(string(k))
defer C.free(unsafe.Pointer(bn))
if C.BN_hex2bn(&n, bn) == 0 {
return nil, nil
}
if C.EC_POINT_mul(curve.curve, pointR, n, pointQ, nil, nil) != 1 {
return nil, nil
}
rx := C.BN_new()
if rx == nil {
return nil, nil
}
defer C.BN_free(rx)
ry := C.BN_new()
if ry == nil {
return nil, nil
}
defer C.BN_free(ry)
if C.EC_POINT_get_affine_coordinates_GFp(curve.curve, pointR, rx, ry, nil) != 1 {
return nil, nil
}
x, _ = new(big.Int).SetString(C.GoString(C.BN_bn2hex(rx)), 16)
y, _ = new(big.Int).SetString(C.GoString(C.BN_bn2hex(ry)), 16)
return
}