How to restrict user to copy from a textbox or paste text to textbox using javascript

This code demonstrate how to restrict user to copy from a textbox or paste text to textbox using JavaScript.

Here is the code :

<script language="javascript">

function copy() {

    alert("Can't copy the text");

    return false;

}

function paste() {

    alert("can't paste text");

    return false;

} 

</script>

<asp:TextBox ID="TextBox2" runat="server" Text="hi" oncopy="return copy();" onpaste="return paste();"></asp:TextBox>

Thanks,
Abhay