Hi all! > The devices apparently use D-H key exchange to produce a 128 bit AES > key which is then used as a stream cipher (presumably in OFB or a > similar mode). Authentication appears to be via a 4 digit pin, > certainly not the best of mechanisms.
The 4-digit PIN should not automatically be dismissed as a bad idea. The device *could* be performing a DH based protocols to bootstrap a strong secret from a week PIN. A secure example of such a protocol (there are many more): Stefan Lucks, Rüdiger Weis: How to turn a PIN into an Iron Beam. 385-396 (In Dimitris Gritzalis, Sabrina De Capitani di Vimercati, Pierangela Samarati, Sokratis K. Katsikas (Eds.): Security and Privacy in the Age of Uncertainty, IFIP TC11 18th International Conference on Information Security (SEC2003), May 26-28, 2003, Athens, Greece. IFIP Conference Proceedings 250 Kluwer 2003, ISBN 1-4020-7449-2) And a simpler one: Michael Roe, Bruce Christianson, David Wheeler. Secure sessions from weak secrets www.cl.cam.ac.uk/TechReports/UCAM-CL-TR-445.pdf Of course I have no idea if this is the technology used. George Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
