if kbig == nil {
		return nil, fail("EC_KEY_get0_private_key")
	}
	pt := C._goboringcrypto_EC_POINT_new(group)
	if pt == nil {
		return nil, fail("EC_POINT_new")
	}
	if C._goboringcrypto_EC_POINT_mul(group, pt, kbig, nil, nil, nil) == 0 {
		C._goboringcrypto_EC_POINT_free(pt)
		return nil, fail("EC_POINT_mul")
	}
	bytes, err := pointBytesECDH(k.curve, group, pt)
	if err != nil {