加密解密（转）

  protected void Page_Load(object sender, EventArgs e)
    {
       
      //加密算法
      string username = "你好";
      //MD5加密 - 得到32位加密数据,数据不好解密。过于复杂。
      username =FormsAuthentication.HashPasswordForStoringInConfigFile(username, "MD5");

      //SHA1加密 - 得到40位加密数据,数据不好解密。过于复杂。
      string username1 = FormsAuthentication.HashPasswordForStoringInConfigFile(username, "SHA1");

      Response.Write(username+"<br>");

      Response.Write(username1+"<br>");

     //解密算法

    //普通加密
      string s = "你好";
 
      string encodestr = "";

      byte[] bytes = System.Text.Encoding.GetEncoding(0).GetBytes(s);
     
      try
      {
          encodestr = Convert.ToBase64String(bytes);
          Response.Write("aa");
      }
      catch
      {
          encodestr = s;
          Response.Write("bb");
      }
      Response.Write(encodestr+"<br>");

    //普通解密
      string decodestr = "";
      byte[] bytes1 = Convert.FromBase64String(encodestr);
      try
      {
          decodestr = System.Text.Encoding.GetEncoding(0).GetString(bytes1);
          Response.Write("cc");
      }
      catch
      {
          Response.Write("dd");
          decodestr = encodestr;
      }
      Response.Write(decodestr+"<br>");

    //普通加密
    string myname = "你好";

    myname = System.Web.HttpUtility.UrlEncode(myname, System.Text.Encoding.UTF8);

    Response.Write(myname+"<br>");

    //普通解密
    myname = System.Web.HttpUtility.UrlDecode(myname, System.Text.Encoding.UTF8);

    Response.Write(myname);
    }