title: How to keep scores from being changed by jail breakers
body: <p>OK . . . </p>
  
  <p>I made a game where I use NSUserDefaults to store high scores.  After placing it on the market, I had a friend show me how he could hack into it and just <em>change</em> high scores-- something I did not know was possible.  With v2.0, I am adding GameCenter, so this becomes a much bigger deal as I post these scores to a leader board.  I do not want jail breakers to be able to just change their high scores and have a bunch of trillions on the high score list. Is there a way to keep high scores saved on the device so that jail breakers can't edit them so easily?    I really liked the simplicity of NSUserDefaults, so I was wondering if there was a way to make these un-see-able to jail breakers, but another save system would be just great.  I save high scores for each individual level on the device and upload total episode scores to Game Center, so I can't just retrieve scores from their servers.</p>
  
  <p>Any help would be appreciated.  Thanks!</p>