How to disable copy/paste from/to EditText

In my application, there is a registration screen, where i do not want the user to be able to copy/paste text into the EditText field. I have set an onLongClickListener on each EditText so that the context menu showing copy/paste/inputmethod and other options does not show up. So the user won't be able to copy/ paste into the Edit fields.

OnLongClickListener mOnLongClickListener = new OnLongClickListener() {

        @Override
        public boolean onLongClick(View v) {
            // prevent context menu from being popped up, so that user
            // cannot copy/paste from/into any EditText fields.
            return true;
        }
    };

But the problem arises if the user has enabled a third-party keyboard other than the Android default, which may have a button to copy/paste or which may show the same context menu. So how do i disable copy/paste in that scenario ?

Please let me know if there are other ways to copy/paste as well. (and possibly how to disable them)

Any help would be appreciated.