I too think the straw man from Dan is an interesting idea. The
alternative that I think Hadriel is suggesting (email style as a
parameter of the E.164-based SIP URI) would probably not survive any
changes of the E.164-based URI by intermediaries -part of the problem
with E.164-based URIs in practice.

John

> -----Original Message-----
> From: Dan Wing [mailto:[EMAIL PROTECTED] 
> Sent: 05 April 2008 19:03
> To: 'Hadriel Kaplan'; [email protected]
> Cc: Elwell, John
> Subject: RE: [Sip] Migration from E.164 to email-style SIP URIs
> 
> Hadriel Kaplan wrote: 
> > > -----Original Message-----
> > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On 
> > > Behalf Of Dan Wing
> > >
> > > Here is a straw-man idea:
> > >
> > > On an outgoing request containing an e164-style URI in the From:
> > > (or PAI, as you prefer), the domain additionally places the user's
> > > email-style URI into a new header (let's call it 
> "email-identity").
> > > It determines the mapping between a user's E.164 URI and email URI
> > > using a flat database (example: +14085551234 -> [EMAIL PROTECTED]).
> > 
> > Interesting proposal.
> > 
> > > This new header is signed along with everything else we like to
> > > sign [choose RFC4474, draft-fischer-sip-e2e-sec-media-00.txt, or
> > > draft-wing-sip-identity-media-02.txt, as you prefer].
> > 
> > You wouldn't be able to use 4474 as is, because it has no way 
> > to sign a new header, afaik.
> 
> Right, RFC4474 is not extensible.
> 
> > (though I'm all for a 4474bis ;)
> > I know this is only a straw-man and too soon to get into the 
> > details, but I can't help myself, so I wonder why you 
> > wouldn't just put this email-style URI *inside* the From-URI 
> > as an escaped uri or user param.  That way it avoids a new 
> > header and gets signed by 4474 as is, and really what you're 
> > saying is it is an alias property of the From-URI.
> 
> That would look something like:
> 
>   From: Dan Wing <sip:[EMAIL PROTECTED];[EMAIL PROTECTED]>
> 
> and the originating domain (cisco.com) would provide strong identity 
> over the entire URI, including the E.164 and the email-style portion
> ([EMAIL PROTECTED]).
> 
> I wanted to avoid signing the E.164 in the From, because we have not 
> yet resolved if we can do that in a meaningful way.
> 
> > > This provides a backwards-compatible way to migrate to email-style
> > > URIs, and gives us strong identity with those email-style URIs.
> > 
> > And lets the UAS offer its user the ability to add both the 
> > e164 and email-forms into its contact address book.  I'm not 
> > sure if that's good or bad, but it's a nice feature.
> 
> Right, but that could also be another attack vector if the
> E.164 is unsigned or only trustable hop-by-hop.
> 
> -d
> 
> 
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