MD5 md5 = new MD5CryptoServiceProvider(); byte[] fromData = System.Text.Encoding.UTF8.GetBytes(myString); byte[] targetData = md5.ComputeHash(fromData); string byte2String = null; for (int i = 0; i < targetData.Length; i++) { byte2String = byte2String+ targetData[i].ToString("x2"); } return byte2String;