สอบถามครับ textbox ห้ามไม่ให้ก๊อบปี้มาวางต้องทำยังไง?

[vb]function noCopyMouse(e) {
        var isRight = (e.button) ? (e.button == 2) : (e.which == 3);
        

        if(isRight) {
            alert('You are prompted to type this twice for a reason!');
            return false;
        }
        return true;
    }


    function noCopyKey(e) {
        var forbiddenKeys = new Array('c','x','v');
        var keyCode = (e.keyCode) ? e.keyCode : e.which;
        var isCtrl;


        if(window.event)
            isCtrl = e.ctrlKey
        else
            isCtrl = (window.Event) ? ((e.modifiers & Event.CTRL_MASK) == Event.CTRL_MASK) : false;
    

        if(isCtrl) {
            for(i = 0; i < forbiddenKeys.length; i++) {
                if(forbiddenKeys[i] == String.fromCharCode(keyCode).toLowerCase()) {
                    alert('You are prompted to type this twice for a reason!');
                    return false;
                }
            }
        }
        return true;
    }  
'เรียกฟังชัน

    Textbox1.Attributes.Add("onmousedown", "return noCopyMouse(event);")
    Textbox1.Attributes.Add("onkeydown", "return noCopyKey(event);")

<asp:TextBox ID="TextBox1" runat="server" 
oncopy ="return false" onpaste="return false" oncut="return false" >