func (curve CurveParams) IsOnCurve(x, y *big.Int) bool {
bnx := C.BN_new()
if bnx == nil {
return false
}
defer C.BN_free(bnx)
bny := C.BN_new()
if bny == nil {
return false
}
defer C.BN_free(bny)
xs := C.CString(x.String())
defer C.free(unsafe.Pointer(xs))
if C.BN_hex2bn(&bnx, xs) == 0 {
return false
}
ys := C.CString(y.String())
defer C.free(unsafe.Pointer(ys))
if C.BN_hex2bn(&bny, ys) == 0 {
return false
}
point := C.EC_POINT_new(curve.curve)
if point == nil {
return false
}
defer C.EC_POINT_free(point)
if C.EC_POINT_set_affine_coordinates_GFp(curve.curve, point, bnx, bny, nil) != 1 {
return false
}
if C.EC_POINT_is_on_curve(curve.curve, point, nil) == 0 {
return false
}
return true
}
func (curve CurveParams) Add(x1, y1, x2, y2 *big.Int) (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)
bnx2 := C.BN_new()
if bnx2 == nil {
return nil, nil
}
defer C.BN_free(bnx2)
bny2 := C.BN_new()
if bny2 == nil {
return nil, nil
}
defer C.BN_free(bny2)
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
}
x2s := C.CString(x2.String())
defer C.free(unsafe.Pointer(x2s))
if C.BN_hex2bn(&bnx2, x2s) == 0 {
return nil, nil
}
y2s := C.CString(y2.String())
defer C.free(unsafe.Pointer(y2s))
if C.BN_hex2bn(&bny2, y2s) == 0 {
return nil, nil
}
pointR := C.EC_POINT_new(curve.curve)
if pointR == nil {
return nil, nil
}
defer C.EC_POINT_free(pointR)
pointA := C.EC_POINT_new(curve.curve)
if pointA == nil {
return nil, nil
}
defer C.EC_POINT_free(pointA)
if C.EC_POINT_set_affine_coordinates_GFp(curve.curve, pointA, bnx1, bny1, nil) != 1 {
return nil, nil
}
pointB := C.EC_POINT_new(curve.curve)
if pointB == nil {
return nil, nil
}
defer C.EC_POINT_free(pointB)
if C.EC_POINT_set_affine_coordinates_GFp(curve.curve, pointB, bnx2, bny2, nil) != 1 {
return nil, nil
}
if C.EC_POINT_add(curve.curve, pointR, pointA, pointB, nil) == 0 {
return nil, nil
}
bnx := C.BN_new()
if bnx == nil {
return nil, nil
}
defer C.BN_free(bnx)
bny := C.BN_new()
if bny == nil {
return nil, nil
}
defer C.BN_free(bny)
if C.EC_POINT_get_affine_coordinates_GFp(curve.curve, pointR, bnx, bny, nil) != 1 {
return nil, nil
}
x, _ = new(big.Int).SetString(C.GoString(C.BN_bn2hex(bnx)), 16)
y, _ = new(big.Int).SetString(C.GoString(C.BN_bn2hex(bny)), 16)
return
}
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
}
// GenerateKey returns a public/private key pair. The private key is
// generated using the given reader, which must return random data.
// TODO(runcom): add support for Go stdlib `elliptic.Curve`, for now unsupported
func GenerateKey(curve elliptic.Curve, rand io.Reader) (priv []byte, x, y *big.Int, err error) {
// rand isn't used with openssl...
// for go stdlib compatibility
//c, _ := curve.(*elliptic.CurveParams)
// to use this pkg
c, ok := curve.(CurveParams)
if !ok {
return nil, nil, nil, errors.New("provided curve is unsupported")
}
k := C.EC_KEY_new()
if k == nil {
return nil, nil, nil, errors.New("can't create key")
}
defer C.EC_KEY_free(k)
if C.EC_KEY_set_group(k, c.curve) != 1 {
return nil, nil, nil, errors.New("can't set ec_group on key")
}
if C.EC_KEY_generate_key(k) != 1 {
return nil, nil, nil, errors.New("can't generate key")
}
blen := C.i2d_ECPrivateKey(k, nil)
if blen == 0 {
return nil, nil, nil, errors.New("can't get private key")
}
buf := make([]C.uchar, int(blen))
pkey := (*C.uchar)(&buf[0])
if C.i2d_ECPrivateKey(k, &pkey) == 0 {
return nil, nil, nil, errors.New("can't get private key")
}
point := C.EC_KEY_get0_public_key(k)
if point == nil {
return nil, nil, nil, errors.New("can't get public key")
}
defer C.EC_POINT_free(point)
rx := C.BN_new()
if rx == nil {
return nil, nil, nil, errors.New("error creating big num")
}
defer C.BN_free(rx)
ry := C.BN_new()
if ry == nil {
return nil, nil, nil, errors.New("errors creating big num")
}
defer C.BN_free(ry)
if C.EC_POINT_get_affine_coordinates_GFp(c.curve, point, rx, ry, nil) != 1 {
return nil, nil, nil, errors.New("can't get public key")
}
x, _ = new(big.Int).SetString(C.GoString(C.BN_bn2hex(rx)), 16)
y, _ = new(big.Int).SetString(C.GoString(C.BN_bn2hex(ry)), 16)
priv = C.GoBytes(unsafe.Pointer(pkey), C.int(blen))
return priv, x, y, nil
}
func freePoint(p *point) {
C.EC_POINT_free(p.p)
p.p = nil
}