So maybe the draft should mention in section 8.1, second paragraph, also the possibility that an attacker may only impersonate B, without doing a full MITM-attack.
Peter > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of ext Dean Willis > Sent: Monday, November 10, 2008 6:03 AM > To: Suresh Krishnan > Cc: [email protected]; [EMAIL PROTECTED]; [EMAIL PROTECTED]; > [EMAIL PROTECTED] > Subject: Re: [Sip] > DISCUSS:draft-ietf-sip-dtls-srtp-frameworkdraft-ietf-sip-dtls- > srtp-framework > > > On Nov 6, 2008, at 2:58 PM, Suresh Krishnan wrote: > > > Hi Eric, > > > > Eric Rescorla wrote: > >> But then the attacker isn't *intercepting* their communications. > >> Alice calls Bob and ends up talking to someone but she knows > >> that she doesn't know who. The point is you can't use this to > >> mount an MITM attack. > > > > Again. I agree with what you said. What I was commenting on is the > > following text from the draft > > > > "Bob would know that an attack was happening. The fact that > > one side can detect this attack means that in most cases where Alice > > and Bob both wish the communications to be encrypted there is not a > > problem." > > > > My question was, how would Bob detect this attack? > > > > I think I understand the question. Let's check. > > Bob is talking, but nobody hears what he says, since he's > encrypted it > for Alice but Alice isn't getting it. Bob may well notice > that there's > something strange here. > > An attacker in this position could also have affected things > such that > the call never reaches Bob. His phone doesn't ring, and Bob isn't > talking to anybody. So how does he know there's an attack? Why would > Eve have even allowed any signaling to get to Bob in the first place > if she had this sort of control? > > Bob can't detect the attack, and this is not an issue with > DTLS-SRTP; > it's a fundamental aspect of the signaling model. > > However, Alice, who is the only party here that's honestly > engaged in > a call and saying something that could be intercepted, CAN > detect the > attack. That's the important piece. > > > -- > Dean > > _______________________________________________ > 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 > _______________________________________________ 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
