KeyedHashAlgorithm algorithm = KeyedHashAlgorithm.Create(algorithmName.ToString().ToUpper(CultureInfo.InvariantCulture));

                if (null == algorithm)

                    throw new InvalidOperationException("Please specify a KeyedHashAlgorithm to use.");

                try

                {

                    algorithm.Key = key;

                    byte[] bytes = algorithm.ComputeHash(data);

                    return bytes;

                }

                finally

                {

                    algorithm.Clear();

                }

  try

                {

                    var keyBytes = Encoding.UTF8.GetBytes(key);

                    var hmac = new HMACSHA1(keyBytes);

                    byte[] bytes = hmac.ComputeHash(data);

                    return Convert.ToBase64String(bytes);

                }

                catch (Exception e)

                {

                    throw e;

                }

                finally

                {

                }