检验密码的处理，望详解

下面是检验密码的处理代码，新手望详解：
#endregion
        Maticsoft.BLL.db_User db = new Maticsoft.BLL.db_User();
        Maticsoft.Model.db_User mode = db.GetModelByUserName(this.mail.Value);
        if (mode != null)
        {
            if (mode.UserPwd == DESEncrypt.Encrypt(this.pwd.Value))
            {
                Session["USERINFO"] = mode;
                Response.Redirect("UserInfo.aspx");
            }
            else
            {
                this.pwd_succeed.InnerText = "用户密码错误";
            }
        }
        else
        {
            this.pwd_succeed.InnerText = "用户密码错误";

        }
    }
}