title: xkcd: Externalities
body: <p>So the April 1, 2013 xkcd <a href="http://xkcd.com/1193/">Externalities</a> web comic features a Skein 1024 1024 hash breaking <a href="http://almamater.xkcd.com">contest</a>. I'm assuming that this must be nothing more than a brute force effort where random strings are hashed in an effort to match Randall's posted hash? Is this correct?</p>
  
  <p>Also, my knowledge of Skein hashing theory is virtually non-existent but being a halfway decent programmer I was able to download and run both <a href="https://code.google.com/p/skeinfish/">SkeinFish</a> (C#) and <a href="http://warper.home.xs4all.nl">Maarten Bodewes</a> Skein implementation (Java) locally in 1024 1024 mode with some input strings. The hashes that they gave, however, were different than the hash that xkcd returned for the same input. This may be an extremely naive question but do different Skein implementations give different hashes? And what Skein implementation is xkcd using?</p>
  
  <p>Thanks for pardoning my ignorance!</p>