这个C#类是一个基于Base64的加密和解密类，用户可以可以使用默认的秘钥进行加密、解密，也可以自己设定秘钥进行加密和解密，非常实用

using System;  using System.Security.Cryptography;   using System.Text;  namespace DotNet.Utilities  {      /// <summary>      /// Encrypt 的摘要说明。      /// </summary>      public class DEncrypt      {          /// <summary>          /// 构造方法          /// </summary>          public DEncrypt()           {           }             #region 使用 缺省密钥字符串 加密/解密string             /// <summary>          /// 使用缺省密钥字符串加密string          /// </summary>          /// <param name="original">明文</param>          /// <returns>密文</returns>          public static string Encrypt(string original)          {              return Encrypt(original,"sharejs.com");          }          /// <summary>          /// 使用缺省密钥字符串解密string          /// </summary>          /// <param name="original">密文</param>          /// <returns>明文</returns>          public static string Decrypt(string original)          {              return Decrypt(original,"sharejs.com",System.Text.Encoding.Default);          }             #endregion             #region 使用 给定密钥字符串 加密/解密string          /// <summary>          /// 使用给定密钥字符串加密string          /// </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>          /// 使用给定密钥字符串解密string          /// </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>          /// 使用给定密钥字符串解密string,返回指定编码方式明文          /// </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));               }           #endregion             #region 使用 缺省密钥字符串 加密/解密/byte[]          /// <summary>          /// 使用缺省密钥字符串解密byte[]          /// </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("sharejs.com");              return Decrypt(encrypted,key);              }          /// <summary>          /// 使用缺省密钥字符串加密          /// </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("sharejs.com");              return Encrypt(original,key);              }           #endregion             #region  使用 给定密钥 加密/解密/byte[]             /// <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);          }                #endregion                                  }  }