private bool VerifyPassword(string password, byte[] passwordHash, byte[] passwordSalt)
        {
            using (var hmac = new HMACSHA512(passwordSalt))
            {
                var computedHash = hmac.ComputeHash(Encoding.UTF8.GetBytes(password));
                for (int i = 0; i < computedHash.Length; i++)
                {
                    if (computedHash[i] != passwordHash[i])
                    {
                        return false;
                    }
                }
                return true;
            }
        }