BitTorrent is one of the most popular ways of file sharing, even though cyberlockers have been gaining ground and even surpassing BitTorrent in some cases in recent years. The large number of sites, the large number of torrents and the p2p nature of the network makes people feel rather secure and private.
Users feel that the torrents they download are somewhat of an open secret and that it's hard for anyone to track them down. But, the reality is that the very p2p nature of BitTorrent is what makes it so easy for others to track down anyone downloading any torrent from a public tracker.
Last year, the YouHaveDownloaded site made quite a splash by displaying any torrent that a particular IP address had downloaded.
The tool wasn't perfect, it didn't detect all downloads and may have had some false positives, but it was enough to uncover some very interesting things, like the fact that there are pirates even at the White House.
That site is gone now, but a new one is here, MyPiracy.net, and it's much more dangerous for pirates. The site also tracks torrent downloads, but it already has four times the data YouHaveDownloaded had, some 430,000 torrents.
Multiply each torrent with tens or thousands of peers and you can get an idea of the amount of data available and stored.
You can check the site's accuracy by simply visiting it, if you've been a naughty pirate or have been using BitTorrent for legitimate purposes, your downloads should be listed. Again, the technology is not perfect, but it should be a wake-up call to many.
The scary part is that the site is by no means informational, copyright holders can use it to get data on who downloaded their stuff. Thankfully, some privacy measures are in place. For one, regular users can only see the torrents downloaded from their IPs.
At the same time, clients can only see the data related to the content they own copyrights to. That is, they will get a list of IP addresses that have downloaded a particular torrent, but they won't be able to see what other torrents those IP addresses have also grabbed.
All of the caveats of using an IP to identify a computer or person apply, false positives and negatives will happen. If you don't have a static IP, you may notice torrents that you didn't download. Same goes if you share your connection.