对称加密类

using System;
using System.Text;
using System.Security.Cryptography;
using System.IO;
using System.Linq;

//摘自 http://topic.csdn.net/u/20101231/09/039bdd22-3f0a-4bbb-908e-d887b4d7bbfe.html?19933

#region 对称加密类
    /// <summary>
    /// 对称加密解密类
    /// </summary>
    public static class SymmetricEncryptClass
    {
       #region 对称加密代码
       /// <summary>
       /// 对称加密方法
       /// </summary>
       /// <param name="strMsg">要加密的数据</param>
       /// <param name="key">加密Key</param>
       /// <param name="IV">加密向量</param>
       /// <returns>返回加密后的数据，类型byte[]</returns>
       public static byte[] SymmetricEncrptFunction(this string strMsg, string key, string IV)
       {
           TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
           SHA1 sha1 = new SHA1CryptoServiceProvider();
           //初始密钥的设定
           string strNamePlusBirthday = key + IV;
           string strKey = new string(strNamePlusBirthday.Reverse().ToArray());
           if (sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).Length > tdes.Key.Length)
           {
               tdes.Key = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).ToString().Substring(0, tdes.Key.Length));
           }
           else if (sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).Length < tdes.Key.Length)
           {
               tdes.Key = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).ToString().PadRight(tdes.Key.Length, ' '));
           }
           //初始向量的设定

           if (sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).Length > tdes.IV.Length)
           {
               tdes.IV = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).ToString().Substring(0, tdes.IV.Length));
           }
           else if (sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).Length < tdes.IV.Length)
           {
               tdes.IV = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).ToString().PadRight(tdes.IV.Length, ' '));
           }
           byte[] encryptBuffer = Encoding.Default.GetBytes(strMsg);
           MemoryStream streamMemory = new MemoryStream();
           CryptoStream cryStream = null;//加密流
           byte[] readBuffer;//用来接受加密数据
           try
           {
               cryStream = new CryptoStream(streamMemory, new TripleDESCryptoServiceProvider().CreateEncryptor(tdes.Key, tdes.IV), CryptoStreamMode.Write);
               cryStream.Write(encryptBuffer, 0, encryptBuffer.Length);
               cryStream.FlushFinalBlock();
           }
           catch
           {
               return null;
           }
           finally
           {
               readBuffer = streamMemory.ToArray();
               cryStream.Close();
               streamMemory.Close();
           }
           return readBuffer;
       }

       #endregion
       #region 对称解密代码
       /// <summary>
       /// 对称解密方法
       /// </summary>
       /// <param name="bufMsg">需要解密的数据</param>
       /// <param name="key">解密Key</param>
       /// <param name="IV">解密向量</param>
       /// <returns>解密后的数据</returns>
       public static string SymmetricDecryptionFunction(this byte[] bufMsg, string key, string IV)
       {
           TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
           SHA1 sha1 = new SHA1CryptoServiceProvider();
           //初始密钥的设定
           string strNamePlusBirthday = key + IV;
           string strKey = new string(strNamePlusBirthday.Reverse().ToArray());
           if (sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).Length > tdes.Key.Length)
           {
               tdes.Key = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).ToString().Substring(0, tdes.Key.Length));
           }
           else if (sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).Length < tdes.Key.Length)
           {
               tdes.Key = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).ToString().PadRight(tdes.Key.Length, ' '));
           }
           //初始向量的设定
           if (sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).Length > tdes.IV.Length)
           {
               tdes.IV = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).ToString().Substring(0, tdes.IV.Length));
           }
           else if (sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).Length < tdes.IV.Length)
           {
               tdes.IV = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).ToString().PadRight(tdes.IV.Length, ' '));
           }
           byte[] readBuffer = bufMsg;
           MemoryStream streamRead = new MemoryStream(readBuffer);
           CryptoStream deCryStream = null;
           byte[] bufferReader;
           try
           {
               deCryStream = new CryptoStream(streamRead, new TripleDESCryptoServiceProvider().CreateDecryptor(tdes.Key, tdes.IV), CryptoStreamMode.Read);
               bufferReader = new byte[readBuffer.Length];
               deCryStream.Read(bufferReader, 0, bufferReader.Length);
           }
           finally
           {
               deCryStream.Close();
               streamRead.Close();
           }
           string deCryString = Encoding.Default.GetString(bufferReader);
           return deCryString;
       }
       #endregion
    }
    #endregion