According to Slashdot, Cox, Time Warner Cable and Comcast have created a joint venture called PolyCipher. PolyCipher in turn is funding research into a project called BitStalker, which according to the project explanation (pdf) will help copyright holders more effectively identify BitTorrent users trading copyrighted files. The goal is to reduce the number of false positives that pop up (about 11% currently) during efforts to identify pirates on P2P networks. Says the study:

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We develop an active probing framework called BitStalker that identifies active peers and collects concrete forensic evidence that they were involved in sharing a particular file. We evaluate the effectiveness of this approach through a measurement study with real, large torrents consisting of over 186,000 peers. We find that the current investigative methods produce at least 11% false positives, while we show that false positives are rare with our active approach.

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A successful TCP probe indicates that the peer is listening on the correct port. However, an effective counter-strategy could be to register arbitrary IP addresses with ports that are opened (such as web servers). The subsequent handshake probe is more conclusive, as it indicates that the BitTorrent protocol is running on the correct port and also identifies the content being shared by a SHA1 hash. The bitfield probe provides stronger evidence still, since it describes all pieces that the peer has downloaded, which implies active sharing. Finally, requesting and subsequently receiving a block of the file provides the strongest form of concrete evidence for file sharing.

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With companies like Comcast poised to merge with NBC Universal -- that seems like an inevitable outcome. By investing in this technology, ISPs could be looking to limit their legal liability for falsely accusing users. But false positives are only a small part of the issues raised when ISPs begin kicking users off of the network for piracy. Keep in mind not all ISPs and users agree that terminating a user's broadband lifeline is a fair punishment for downloading a handful of LOST episodes, or that ISPs should be propping up struggling entertainment industry business models.

But that aside, there's questions surrounding who tracks users across ISPs, how to treat multi-user homes, or whether small ISPs can afford the cost of such systems. There's still limited transparency into these processes (Qwest for instance absolutely refused to talk to us about any specifics behind their user termination program), no independent oversight, and no recourse for the falsely accused. Meanwhile studies have show that many pirates are also significant buyers of online content, so by kicking them offline -- both ISPs and the entertainment industry are losing potential customers.