TorrentZip creates byte-for-byte exact zip files on any machine.  This allows
people to join a torrent (after they have converted their zip files) with a
particular set of files, thus preventing them from having to download the
entire set of files again.  Because of the way TorrentZip creates identical
zips, the file hashes will always match those in the original torrent. 

WWW: http://trrntzip.sourceforge.net
     https://sourceforge.net/projects/trrntzip