Skype reverse-engineered and open sourced

Discussion in 'The Water Cooler' started by reghakr, Jun 3, 2011.

  1. reghakr

    reghakr Excellent Member

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    How soon will Microsoft blow?

    There have been many analyses of Skype’s behaviour over the years (the most famous perhaps is from Baset and Schultzrinne), but as far as Vulture Central is aware, nobody has yet gone so far as to reverse-engineer the whole kit-and-caboodle.

    That’s the claim being made by Efim Bushmanov on this blog, where he offers his reverse-engineered Skype source code available for download.

    His work is almost certain to spark debate over the legality – and license-compliance – of reverse-engineering the software. It’s also quite likely to spark a response from Skype’s new owner, Microsoft.

    The Register has not yet had the time to install or test the code (if that were, in fact, legal to do), so we can’t vouch for its operation.

    Whether Bushmanov has broken any laws or breached any license terms depends on the conditions under which he’s undertaken the project (and to some extent, the jurisdiction in which he worked).

    It’s hard to replicate perfectly the behaviour of any software under completely clean-room conditions, and probably even harder to prove that such conditions existed. Bushmanov would at the very least have to demonstrate that he worked without a copy of the software to hand – that somebody else ran the software and observed its behaviours. The authors of the reverse-engineered copy would have to write their software solely from Skype’s reported behaviour under different conditions.

    According to this discussion on Hacker News, Bushmanov seems to be including original Skype binaries in its downloads, which would be a no-no. However, HN’s interpretation is based on the filenames rather than the contents of the files; perhaps Bushmanov simply didn’t have the nous to give his files names that weren’t subject to confusion.

    The Register does however anticipate a swift response from Microsoft, if the software is what it claims to be.

    Source: Skype reverse-engineered and open sourced ? The Register
     
  2. reghakr

    reghakr Excellent Member

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    Skype has been in the news a lot recently, mainly due to rumors of it being acquired a few months before a planned IPO. We thought Facebook and Google may pounce on the company for as much as $4 billion, but then Microsoft turned up, put $8.5 billion on the table, and walked away with their very expensive prize.

    Now Microsoft own the most popular VoIP service out there, and surely plans to make it an integral part of their operations and products going forward. At the same time, one researcher has decided he wants to make Skype open source by reverse engineering the protocol the service uses.

    In fact, he claims to have already achieved that reverse engineering feat on a new skype-open-source blog. The source code has been posted for versions 1.x/3.x/4.x of Skype as well as details of the rc4 layer arithmetic encoding the service uses.

    While his intention may be to recreate Skype as an open source platform, it is doubtful he will get very far without facing an army of Microsoft lawyers. Skype is not an open platform, and Microsoft will want to keep it that way. Posting reverse engineered code online is not going to go down well in Redmond and this is surely a blog that will disappear shortly.

    In terms of this code working as an open source client for Skype, the chances are very slim it will function correctly, if at all. These are old versions of Skype, and all Microsoft need to do is detect and stop them connecting to the service. Even if this was the latest version, Skype could apply an update that deems it unusuable until further work is done to figure out what was changed in the official version.

    At best, the code available for download will give an insight into how Skype is put together for any interested parties. Unfortnately, that may form a few security risks for Skype if holes are found that can be exploited.

    Source: The Skype protocol has been reverse engineered (UPDATED)
     

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