//加密要传递的参数
string Id=Convert.ToBase64String(System.Text.Encoding.Default.GetBytes("aa12")).Replace("+","%2B");
Response.Write("加密字符为：" +Id+"<br>");
Response.Redirect("Default.aspx?id="+Id);
//解密
string Id=System.Text.Encoding.Default.GetString(Convert.FromBase64String(Request.QueryString["id"].ToString().Resplace("%2B","+")));
Response.Write("解密字符为：" + id+"<br>");