func NewPublicKeyECDH(curve string, bytes []byte) (*PublicKeyECDH, error) {
	if len(bytes) < 1 {
		return nil, errors.New("NewPublicKeyECDH: missing key")
	}

	nid, err := curveNID(curve)
	if err != nil {
		return nil, err
	}

	group := C._goboringcrypto_EC_GROUP_new_by_curve_name(nid)
	if group == nil {
		return nil, fail("EC_GROUP_new_by_curve_name")
	}
	defer C._goboringcrypto_EC_GROUP_free(group)

	// call returns.
	runtime.SetFinalizer(k, (*PublicKeyECDSA).finalize)
	return k, nil
}

func newECKey(curve string, X, Y BigInt) (*C.GO_EC_KEY, error) {
	nid, err := curveNID(curve)
	if err != nil {
		return nil, err
	}
	key := C._goboringcrypto_EC_KEY_new_by_curve_name(nid)
	if key == nil {
		return nil, fail("EC_KEY_new_by_curve_name")
	}
	group := C._goboringcrypto_EC_KEY_get0_group(key)