How to prevent user pasting text in a textbox?

Very Easy Solution:

<input name="ReceiveNo" type="text" class="txtbox" onkeypress="validate(event)" maxlength="11" value="${cpCon.receiveNo}" required tabindex="34" onCopy="return false" onDrag="return false" onDrop="return false" onPaste="return false" autocomplete=off />

This worked for me very well. No one can paste now into your textbox using right button paste option of mouse or pressing ctrl+v from the keyboard.