 <p>If you are referring to the mangled key of <code>files</code> array then it's raw infohash - check out the spec:</p> <ul> <li><a href="https://wiki.theory.org/BitTorrentSpecification#Tracker_.27scrape.27_Convention" rel="nofollow">https://wiki.theory.org/BitTorrentSpecification#Tracker_.27scrape.27_Convention</a></li> <li><a href="http://wiki.vuze.com/w/Scrape" rel="nofollow">http://wiki.vuze.com/w/Scrape</a></li> </ul>