Another "solution" is to not do it. By that I mean, use RFC 4474 for domain-based security, and if you insist on using phone numbers, then it's not "secured that way".
Before the flaming start: by definition, if something is addressed by a phone number, it is something that is likely to be reacheable through the PSTN. The way security works in the PSTN is completely different. The media is almost never encrypted for one. So in the context of SIP, it means there is a gateway somewhere destroying the end-to-end nature of the encryption. Even for the Identity, it's different. For one thing, the Identity assertion is not end-to-end à-la-RFC 4474. So, I'm proposing that if you are using phone numbers as your identity, then it is not a design requirement of this group to re-invent a "better" identity security system for the PSTN. It's not because something is a problem that it necessarily needs to be solved. My 2 cents. > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of Jonathan Rosenberg > Sent: Monday, February 18, 2008 11:36 > To: Paul Kyzivat > Cc: IETF SIP List > Subject: Re: [Sip] New I-D on RFC4474 and phone numbers > > I agree that something along the lines of enum could solve > this problem, and I believe there was a draft that proposed > such a thing. This has been discussed since the start of rfc4474. > > However, I fear that saying, 'use enum' is kind of like > saying, we'll just use an All-Knowing Oracle, so lets figure > out the interface protocol to the Oracle. The easy part is > the interface (the enum mechanism). The actual hard problem > is how to get those entries populated. The deployment of > public enum has been - shall we say - less than spectacular. > I'd hate for that to be our only solution. Not that its > obvious what else to do; though I do suggest in my draft how > domain based authentication, when combined with whitelists > and blacklists, can help. > > -Jonathan R. > > Paul Kyzivat wrote: > > Jonathan, > > > > I guess the time has come for this discussion, since John Ewell has > > also submitted a draft on this subject. > > > > I thought the problem was already well known, but perhaps > not. IMO the > > main thing now is to figure out the *solution* to the problem! > > IMO a solution is to use a 4474-style approach, but where the > > certificate is tied to just the phone number, not to some arbitrary > > domain name. That of course would depend on a model where > the "owner" > > of the phone number is the one who may obtain the > certificate for that number. > > > > My thought is that we already have an algorithmic mapping from an > > E.164 phone number to a domain name, defined by enum. If the sender > > puts an > > E.164 number in From, and can sign it with a cert for the > enum mapped > > domain name corresponding to that number, then that ought > to be valid > > proof of the validity of the sender. > > > > In those places where public enum is in operation, I think there is > > already a legal mechanism in place to give the owner of record of a > > particular phone number control over the contents of the > corresponding > > DNS entry. That should also be sufficient to allow a certificate > > authority to assign a cert to that same owner. > > > > Combine all that and you have a complete e2e identity model > for phone > > numbers, based on public enum. And that can be true even if public > > enum isn't used to *route* the calls to that number. So it could be > > used for "unlisted" numbers. > > > > To use this approach the From header should contain either > a TEL URI, > > or a sip/sips URI containing the enum-mapped domain name > corresponding > > to the phone number. (I would rather see the TEL used for > this - it is > > more user friendly.) > > > > Thanks, > > Paul > > > > Jonathan Rosenberg wrote: > >> I just submitted: > >> > http://www.ietf.org/internet-drafts/draft-rosenberg-sip-rfc4474-conce > >> rns-00.txt > >> > >> > >> This is basically a discussion on the security properties > of rfc4474 > >> with phone numbers, and a comparison to rfc3325 in this > case. Also a > >> discussion on what happens to dtls-srtp. > >> > >> Comments welcome. > >> > >> -Jonathan R. > > > > -- > Jonathan D. Rosenberg, Ph.D. 499 Thornall St. > Cisco Fellow Edison, NJ 08837 > Cisco, Voice Technology Group > [EMAIL PROTECTED] > http://www.jdrosen.net PHONE: (408) 902-3084 > http://www.cisco.com > _______________________________________________ > Sip mailing list http://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 http://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
