At Thu, 31 Jul 2008 16:47:13 -0400, Hadriel Kaplan wrote: > > > > > -----Original Message----- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dan > > Wing > > > > Thank you - this is the first description of a codec attack that > > anyone has explained. > > > > So a beneficial change (adding a codec and doing transcoding for > > the user) is okay, but a non-benficial change (removing a good- > > sounding codec for the end equipment [wideband] or for the network > > [iSAC]) is an attack? > > I still don't buy it. Honestly, exactly how much benefit does an > attacker get by "downgrading" your codec? If there is no > benefit/motivation for an attacker, why is this a threat we care > about?
Funny you should mention that. It's becoming increasingly clear that VBR codecs leak a fair amount of information, even when they are encrypted [WBC+08]. So, if, for instance, you were planning to use a fixed-rate codec and an attacker could force you into a VBR codec, that might leak information. -Ekr [WBC+08] Charles Wright, Lucas Ballard, Scott Coull, Fabian Monrose, Gerald Masson, "Spot me if you can: Uncovering spoken phrases in encrypted VoIP conversations", IEEE Security 2008. _______________________________________________ Sip mailing list https://www.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [EMAIL PROTECTED] for questions on current sip Use [EMAIL PROTECTED] for new developments on the application of sip
