This slide deck, from the recent Black Hat Europe 2006 conference..
- Silver Needle in the Skype, by Philippe BIONDI and Fabrice DESCLAUX (2006)
..provides an intriguing look inside the Skype executable, revealing the fairly great lengths its creators went to in attempting to obfuscate its code and workings. Also dissected are the ciphering techniques applied to Skype PDUs (protocol data units, aka packets). The deck illustrates creatively effective use of various debugging/disassembling tools. Icing on the proverbial cake are their some-assembly-required instructions for how to patch skype.exe for use in creating your own closed, private P2P network
This work adds to the body of openly disseminated information about this very closed P2P network and program. For reference, here are two earlier analyses..
- An Analysis of the Skype Peer-to-Peer Internel Telephony Protocol, by Salman A. Baset and Henning Schulzrinne (2004)
- Skype Security Overview – Rev 1.6 – 1/26/05, By Simson L. Garfinkel.