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Jan 08 2015

Tribler: a (worrying) P2P client

triblerTribler is a new P2P client that made the headlines last month.   It was claimed to make bitTorrent  unstoppable and offer anonymity.   I had a look at it and played with.

This is an open source project from the University of Delft.  It has been partly funded by the Dutch Ministry of Economic Affairs.  The project started in January 2008.  Tribler is worrying to both content owners and users.

To content owners, Tribler is worrying with its features.

  •  Tribler is more convivial than other P2P clients.   It integrates in the client several functions.  First, it allows to search torrents from the client user interface within its currently connected clients.  In other words, it does not need a central tracker to keep the torrents pointers.   Thus, it is more robust and also easier to use than other clients.  If the expected content is popular, the likelihood to find it within the connected community is high.  Thus, it is unnecessary to leave the application to find torrents on trackers. Of course, it can import torrents from any external trackers such as mininova.  Thus, when content is not available in the community, the user may use traditional trackers.
    The second interesting feature is that it emulates video streaming using standard torrents.  In this mode, it buffers the video and starts to play it within the application after a few seconds.  From the user point of view, it is similar to streaming from a cyberlocker (with the difference that, once viewing completed, there is a full copy of the content on the user’s computer).
    These features are not new (emule allowed to search within it, Bittorrent Pro offers an HD player inside it…).  However,  Tribler nicely packages them.  The user experience is neat.
  • Tribler promises anonymity.  It uses a Tor-like onion structure to access the different peers.  Or at least, it should do in the future.  With the current version, it is clearly announced that it is still beta.   Furthermore, all the current peers were directly connected.  Only an experiemental torrent used the feature.  However, once validated and activated, it should become harder to trace back the seeders.

To users,Tribler is worrying for its security.  Tribler promises anonymity.  Unfortunately, this is not the case.  “Yawning angel” analyzed the project.  Although his analysis was not thorough, it highlighted several critical flaws in the used protocol.  As it is possible to define circuits of arbitrary length, it would be possible to create congestion and thus create a kind of DoS.  More worrying there are several severe cryptographic mistakes such as improper use of ECB mode, fixed IV in OFB…  His conclusion was:

For users, “don’t”. Cursory analysis found enough fundamental flaws, and secure protocol design/implementation errors that I would be reluctant to consider this secure, even if the known issues were fixed. It may be worth revisiting in several years when the designers obtain more experience, and a thorough third party audit of the improved code and design has been done.

Lessons:

  • P2P seems not yet dead.  Streaming emulation may change the balance with streaming cyber lockers.
  • Be very cautious about claimed anonymity.  Developing a robust Tor-like solution requires an enormous effort and deep knowledge of cryptography and secure protocols.  Tor is continuously under attack.
  • Universities may finance projects that will facilitate piracy.  “Openess of the Internet” to fight censorship does not mandate to watch content within the client.  The illustrating screenshot of Tribler on the Delft university page clearly shows some copyrighted movies offered to sharing.

2 comments

  1. wx

    They openly state that the project is not yet mature and can’t be relied upon so the “flaws were found” news wasn’t really news. Watching content within the client isn’t necessary for anonymity but it’s a neat feature so criticizing the project for it isn’t very smart. How can you see that a file is a movie and has copyright from just a screenshot? You do know that’s impossible right?

    1. wunderbarb

      I clearly stated in the post that

      it is clearly announced that it is still beta

      I just point to a paper analyzing its security. And the lesson 2 is that making an anonymous system is a complex task
      Did you attempt to examine referenced screenshot? Amongst the twenty thumbnails, a few of them are unambiguously copyrighted works (and I do not point to the trailers). Did you have a look at the proposed channels? No copyrighted content?

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