How do you disable copy paste within an iframe?

I am using google viewer api and I want to disable the copy paste functionality within the frame.
example:

<iframe src="http://docs.google.com/gview?url=http://infolab.stanford.edu/pub/papers/google.pdf&embedded=true" style="width:600px; height:500px;" frameborder="0"></iframe>

Here's my solution (from my comment):

One idea I'm thinking of is overlaying a transparent div on the iframe so you can't interact with it at all.

DEMO

HTML

<div id="container">
  <div id="overlay">
  </div>
  <iframe src="http://docs.google.com/gview?url=http://infolab.stanford.edu/pub/papers/google.pdf&embedded=true" frameborder="0"></iframe>
</div>

CSS

#overlay {
  width:590px;
  height:500px;
  z-index: 1;
  background-color:rgba(255,255,0,0.1);
}
iframe {
  width:600px;
  height:500px;

}
#container {
  position: relative;
}
#overlay, iframe {
  position: absolute;
  top: 0;
  left: 0;
}

I made the overlay (yellow box) width 590px so you still have 10px for the scrollbar.