一起来看下代码，新手朋友多学习下！

    using System;
    using System.Text;
    using System.Globalization;
    using System.Security.Cryptography;
    using System.Windows.Forms;
    namespace Jh.Encrypts
    {
     public class JhEncrypt
     {
      /// <summary>
      /// 构造方法
      /// </summary>
      public JhEncrypt()
      {
      }
      /// <summary>
      /// 使用缺省密钥字符串加密
      /// </summary>
      /// <param name="original">明文</param>
      /// <returns>密文</returns>
      public static string Encrypt(string original)
      {
       return Encrypt(original,"JASONHEUNG");
      }
      /// <summary>
      /// 使用缺省密钥解密
      /// </summary>
      /// <param name="original">密文</param>
      /// <returns>明文</returns>
      public static string Decrypt(string original)
      {
       return Decrypt(original,"JASONHEUNG",System.Text.Encoding.Default);
      }
      /// <summary>
      /// 使用给定密钥解密
      /// </summary>
      /// <param name="original">密文</param>
      /// <param name="key">密钥</param>
      /// <returns>明文</returns>
      public static string Decrypt(string original, string key)
      {
       return Decrypt(original,key,System.Text.Encoding.Default);
      }
      /// <summary>
      /// 使用缺省密钥解密,返回指定编码方式明文
      /// </summary>
      /// <param name="original">密文</param>
      /// <param name="encoding">编码方式</param>
      /// <returns>明文</returns>
      public static string Decrypt(string original,Encoding encoding)
      {

      return Decrypt(original,"JASONHEUNG",encoding);
      }
      /// <summary>
      /// 使用给定密钥加密
      /// </summary>
      /// <param name="original">原始文字</param>
      /// <param name="key">密钥</param>
      /// <param name="encoding">字符编码方案</param>
      /// <returns>密文</returns>
      public static string Encrypt(string original, string key)
      {
       byte[] buff = System.Text.Encoding.Default.GetBytes(original);
       byte[] kb = System.Text.Encoding.Default.GetBytes(key);
       return Convert.ToBase64String(Encrypt(buff,kb));
      }
      /// <summary>
      /// 使用给定密钥解密
      /// </summary>
      /// <param name="encrypted">密文</param>
      /// <param name="key">密钥</param>
      /// <param name="encoding">字符编码方案</param>
    /// <returns>明文</returns>
      public static string Decrypt(string encrypted, string key,Encoding encoding)
      {
       byte[] buff = Convert.FromBase64String(encrypted);
       byte[] kb = System.Text.Encoding.Default.GetBytes(key);
       return encoding.GetString(Decrypt(buff,kb));
      }
      /// <summary>
      /// 生成MD5摘要
      /// </summary>
      /// <param name="original">数据源</param>
      /// <returns>摘要</returns>
      public static byte[] MakeMD5(byte[] original)
      {
       MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
       byte[] keyhash = hashmd5.ComputeHash(original);
       hashmd5 = null;
       return keyhash;
      }
      /// <summary>
      /// 使用给定密钥加密
      /// </summary>
      /// <param name="original">明文</param>
      /// <param name="key">密钥</param>
      /// <returns>密文</returns>
      public static byte[] Encrypt(byte[] original, byte[] key)
      {
       TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();
       des.Key =  MakeMD5(key);
       des.Mode = CipherMode.ECB;

       return des.CreateEncryptor().TransformFinalBlock(original, 0, original.Length);
      }
      /// <summary>
      /// 使用给定密钥解密数据
      /// </summary>
      /// <param name="encrypted">密文</param>
      /// <param name="key">密钥</param>
      /// <returns>明文</returns>
      public static byte[] Decrypt(byte[] encrypted, byte[] key)
      {
       TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();
       des.Key =  MakeMD5(key);
       des.Mode = CipherMode.ECB;
       return des.CreateDecryptor().TransformFinalBlock(encrypted, 0, encrypted.Length);
      }

      /// <summary>
      /// 使用给定密钥加密
      /// </summary>
      /// <param name="original">原始数据</param>
      /// <param name="key">密钥</param>
      /// <returns>密文</returns>
      public static byte[] Encrypt(byte[] original)
      {
       byte[] key = System.Text.Encoding.Default.GetBytes("JASONHEUNG");
       return Encrypt(original,key);
      }
      /// <summary>
      /// 使用缺省密钥解密数据
      /// </summary>
      /// <param name="encrypted">密文</param>
      /// <param name="key">密钥</param>
      /// <returns>明文</returns>
      public static byte[] Decrypt(byte[] encrypted)
      {
       byte[] key = System.Text.Encoding.Default.GetBytes("JASONHEUNG");
       return Decrypt(encrypted,key);
      
       }

       }
      }