title: Modifying Binary Save Game Data (iPhone)
body: <p>Just for fun, I'm trying to hack my saved game data for the Ghostbusters iPhone app (<a href="https://itunes.apple.com/us/app/ghostbusters/id583354857?mt=8&amp;uo=4" rel="nofollow">AppStore link</a>).</p>
  
  <p>The following sites describe replacing <code>Documents/save.dat</code> with the pre-hacked version:</p>
  
  <ul>
  <li><a href="http://www.iapphacks.com/ios-free-hacks-f3/ghostbusters-v1-0-1-t8597.html" rel="nofollow">http://www.iapphacks.com/ios-free-hacks-f3/ghostbusters-v1-0-1-t8597.html</a></li>
  <li><a href="http://mobilegamingsquad.wordpress.com/2013/01/24/ghostbusters-hack/" rel="nofollow">http://mobilegamingsquad.wordpress.com/2013/01/24/ghostbusters-hack/</a></li>
  </ul>
  
  <p>However, I want to modify the data myself.  Using a hex-editor on my <code>save.dat</code> revealed the following dead-ends:</p>
  
  <ol>
  <li>I could not find the value for the amount of money in any combination of the following: (little endian, big endian), (unsigned, signed), (integer, float), (4, 6, 8, 16 byte value), (1 through 15 byte offsets)</li>
  <li>Any small change (ie: item purchase) seems to completely rewrite and change the data file.</li>
  <li>A quick scan of the file in ASCII reveals no text clues to the format of the file.  <em>ADD:</em> In fact, all ASCII strings within the file seem completely random.</li>
  <li>The linux command <code>file</code> simply identified the file as <code>data</code>. </li>
  <li><em>NEW</em> Compressing the file enlarges it, so the file is likely compressed or encrypted.</li>
  <li><em>NEW</em> I'm neither jailbroken nor an iOS developer, so I do not have access to the app's internal memory.</li>
  </ol>
  
  <p>How might this file be encoded?  Any suggestions on how I might modify it manually?</p>