Re: [TLS] TLS-OBC proposal
Nikos Mavrogiannopoulos <nmav@gnutls.org> Thu, 01 September 2011 11:49 UTC
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Date: Thu, 01 Sep 2011 13:51:08 +0200
From: Nikos Mavrogiannopoulos <nmav@gnutls.org>
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Subject: Re: [TLS] TLS-OBC proposal
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On 08/22/2011 07:53 PM, Dirk Balfanz wrote: > Dear TLS-WG, > > I few weeks ago I presented a proposal for an "origin-bound certificates" > TLS extension at IETF 81. It's much easier to understand what this extension > is trying to accomplish when presented in a broader context of web > authentication (which I tried to give in Quebec), so I put together a little > web site that is supposed to do just that for those who couldn't be at the > IETF meeting: http://browserauth.net (This took me a little while, hence the > delay in sending out the I-D). [...] > All feedback is welcome, of course, but if you can't think of anything to > comment on, I have a couple particular questions: I like the proposal. As far as I understand you try to fix the usability problem of using multiple certificates for different sites. This is similar to an SSH-style authentication for users. As a side-effect pseudonymity can be achieved. Some minor comments. * In http://www.browserauth.net/tls-client-authentication you mention the inability to log-out as one reason that TLS client authentication fails. However this is not addressed by OBC if I understand correctly. (to be honest I think that the inability to log-out is just a UI problem. TLS authentication does not need to imply log-in. You might have buttons login and logout that will log the user in and out even if TLS with authentication was used) * Why you require a critical X.509 extension for that? (I also don't like the IA5String... why not UTF8?) * After having read the proposal the name OBC was clear to me. However before reading it, the name didn't give any clue (to me) of the proposal. > - in Section 2.1.1 we currently stipulate that the client include the origin > of the origin-bound cert as part of the OBC X.509 extension. When we > implemented this, we didn't really know what to do with that data on the > server side. If the client also uses TLS-SNI, then we could imagine > comparing the SNI and OBC origins in some manner on the server side, but > there isn't really a vehicle to signal an error back to the client saying > "your SNI and OBC origins don't match". Similarly, we could perhaps at some > higher layer compare the HTTP "Host" header with the OBC origin, but then > again - what do you do when they don't match? I'd send a TLS alert or do nothing. What does this check add? > Respond with a 400 at the HTTP > layer? An alternative to the current language in the I-D would be to simply > mark the cert as origin-bound, but without putting the origin itself into > the cert. Any thoughts? I don't like having the origin in the certificate as a critical extension. regards, Nikos
- [TLS] TLS-OBC proposal Dirk Balfanz
- Re: [TLS] TLS-OBC proposal Anders Rundgren
- Re: [TLS] TLS-OBC proposal Chris Richardson
- Re: [TLS] TLS-OBC proposal Wan-Teh Chang
- Re: [TLS] TLS-OBC proposal Chris Newman
- Re: [TLS] TLS-OBC proposal Dirk Balfanz
- Re: [TLS] TLS-OBC proposal Dirk Balfanz
- Re: [TLS] TLS-OBC proposal Dirk Balfanz
- Re: [TLS] TLS-OBC proposal Nikos Mavrogiannopoulos
- Re: [TLS] TLS-OBC proposal Dirk Balfanz
- Re: [TLS] TLS-OBC proposal Nikos Mavrogiannopoulos
- Re: [TLS] TLS-OBC proposal Anders Rundgren
- Re: [TLS] TLS-OBC proposal Nikos Mavrogiannopoulos
- Re: [TLS] TLS-OBC proposal Anders Rundgren
- Re: [TLS] TLS-OBC proposal Martin Rex
- Re: [TLS] TLS-OBC proposal Nico Williams
- Re: [TLS] TLS-OBC proposal Nico Williams
- Re: [TLS] TLS-OBC proposal Nico Williams