沒什么好說的，直接上類。

using System;using System.IO;using System.Security.Cryptography;using System.Text;namespace Secret{    public class md5    {        /// <summary>        /// MD5加密        /// </summary>        /// <param name="s">需要加密的字符串</param>        /// <returns></returns>        public static string EncryptMD5(string s)        {            var md5 = new System.Security.Cryptography.MD5CryptoServicePRovider();            var result = "";            if (!string.IsNullOrWhiteSpace(s))            {                result = BitConverter.ToString(md5.ComputeHash(UnicodeEncoding.UTF8.GetBytes(s.Trim())));            }            return result;        }    }    public class DES    {        //DES加密秘鑰，要求為8位        private const string desKey = "xianglk1";        //默認密鑰向量        private static byte[] Keys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };        /// <summary>        /// DES加密        /// </summary>        /// <param name="encryptString">待加密的字符串，未加密成功返回原串</param>        /// <returns></returns>        public static string EncryptDES(string encryptString)        {            try            {                byte[] rgbKey = Encoding.UTF8.GetBytes(desKey);                byte[] rgbIV = Keys;                byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);                DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider();                MemoryStream mStream = new MemoryStream();                CryptoStream cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write);                cStream.Write(inputByteArray, 0, inputByteArray.Length);                cStream.FlushFinalBlock();                return Convert.ToBase64String(mStream.ToArray());            }            catch            {                return encryptString;            }        }        /// <summary>        /// DES解密        /// </summary>        /// <param name="decryptString">待解密的字符串，未解密成功返回原串</param>        /// <returns></returns>        public static string DecryptDES(string decryptString)        {            try            {                byte[] rgbKey = Encoding.UTF8.GetBytes(desKey);                byte[] rgbIV = Keys;                byte[] inputByteArray = Convert.FromBase64String(decryptString);                DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();                MemoryStream mStream = new MemoryStream();                CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write);                cStream.Write(inputByteArray, 0, inputByteArray.Length);                cStream.FlushFinalBlock();                return Encoding.UTF8.GetString(mStream.ToArray());            }            catch            {                return decryptString;            }        }    }}