Re: [TLS] Accepting that other SNI name types will never work.
"Blumenthal, Uri - 0553 - MITLL" <uri@ll.mit.edu> Wed, 09 March 2016 15:50 UTC
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From: "Blumenthal, Uri - 0553 - MITLL" <uri@ll.mit.edu>
To: Hannes Tschofenig <hannes.tschofenig@gmx.net>, Adam Langley <agl@imperialviolet.org>, "tls@ietf.org" <tls@ietf.org>
Thread-Topic: [TLS] Accepting that other SNI name types will never work.
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Date: Wed, 09 Mar 2016 15:37:00 +0000
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Subject: Re: [TLS] Accepting that other SNI name types will never work.
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Based on your explanation, the best solution architecture would be based on *attribute* certificates (individual attributes signed independently by their corresponding Attribute Authorities), rather than the current “all-crammed-in” certificates. The downside of the above is that this approach isn’t wide-spread, and would be computationally more expensive (the need to potentially verify at least two attributes, possibly more - instead of just dealing with one signature that covers everything). -- Regards, Uri Blumenthal On 3/9/16, 9:05 , "TLS on behalf of Hannes Tschofenig" <tls-bounces@ietf.org on behalf of hannes.tschofenig@gmx.net> wrote: >Hi Adam, > >as Thomas mentioned in his email we are looking into extending the SNI >functionality. > >Let me explain why we are doing it. > >We are focused on Internet of Things deployments and we want to use >TLS/DTLS there to provide communication security. The use of TLS/DTLS >would solve some of the problems we see in deployments today where >either no communication security is used (such as in the BMW Connected >Drive example) or where custom security solutions are used. We want to >make it easy for developers to add commonly used security services to >their applications. > >Everything fine so far. > >In many deployments the IoT device acts as a client and initiates the >connection to some cloud-based infrastructure (or to some gateway). In >other deployments the IoT device needs to act as a server. In fact, in >many home network/small enterprise deployments this seems to be the >envisioned model. > >Assuming that every IoT device has a domain name is not desired or >useful. Instead, the CORE working group has developed the so-called >Resource Directory, which acts as a rendezvous point, and may even have >more capabilities -- with extensions, like caching of data, while the >IoT devices sleeps. ("Sleeping devices" consume less energy.) > >Now, we had to come up with another story of what information to put >into certificates or, alternatively, forget the use of certificates. > >I know that the timing isn't necessarily in our favor. You guys are >trying to move the TLS 1.3 spec along and our contribution is still >subject to (longer) discussion at the CORE working group. I also >understand that you may not necessarily be super interested in IoT usage >either. > >I still hope that this can be taken into consideration. I saw the >proposal from Martin about defining another extension. This may be an >option and maybe the answer is as simple as "don't use certificates for >such scenarios". > >I believe other organizations who are also looking into these types of >IoT scenarios will sooner or later also figure out that there is a >problem. > >Ciao >Hannes > > >On 03/03/2016 07:49 PM, Adam Langley wrote: >> The Server Name Indication (SNI) extension in TLS has a provision to >> provide names other than host names[1]. None have even been defined to >> my knowledge, but it's there. >> >> OpenSSL (and possibly others) have had a long-standing bug[2] (fixed >> in master) that means that different types of names will cause an >> error. To be clear: I live in a glass house and am not throwing >> stones; these things happen. However, it means that a huge fraction of >> the TLS deployment will not be able to accept a different name type >> should one ever be defined. (This issue might have been caused by the >> fact that the original[3] spec didn't define the extension in such a >> way that unknown name types could be skipped over.) >> >> Therefore we (i.e. BoringSSL, and thus Google) are proposing to give >> up on this and implement our parser such that the SNI extension is >> only allowed to contain a single host name value. (This is compatible >> with all known clients.) We're assuming that since this is already the >> de-facto reality that there will be little objection. I'm sending this >> mostly to record the fact so that, if someone tries to define a new >> name type in the future, they won't waste their time. >> >> If the community wishes to indicate a different type of name in the >> future, a new extension can be defined. This is already effectively >> the case because we wouldn't fight this level of incompatibility when >> there's any other option. >> >> (I think the lesson here is that protocols should have a single joint, >> and that it should be kept well oiled. For TLS, that means that >> extensions should have minimal extensionality in themselves and that >> we should generally rely on the main extensions mechanism for these >> sorts of things.) >> >> [1] https://tools.ietf.org/html/rfc6066#section-3 >> [2] >>https://github.com/openssl/openssl/blob/OpenSSL_1_0_1-stable/ssl/t1_lib.c >>#L1066 >> – note that the data pointer is not updated. >> [3] https://tools.ietf.org/html/rfc4366#section-3.1 >> >> >> Cheers >> >> AGL >> >
- [TLS] Accepting that other SNI name types will ne… Adam Langley
- Re: [TLS] Accepting that other SNI name types wil… Eric Rescorla
- Re: [TLS] Accepting that other SNI name types wil… Adam Langley
- Re: [TLS] Accepting that other SNI name types wil… Salz, Rich
- Re: [TLS] Accepting that other SNI name types wil… Martin Thomson
- Re: [TLS] Accepting that other SNI name types wil… Richard Moore
- Re: [TLS] Accepting that other SNI name types wil… Martin Thomson
- Re: [TLS] Accepting that other SNI name types wil… Dave Garrett
- Re: [TLS] Accepting that other SNI name types wil… Martin Thomson
- Re: [TLS] Accepting that other SNI name types wil… Fossati, Thomas (Nokia - GB)
- Re: [TLS] Accepting that other SNI name types wil… Fossati, Thomas (Nokia - GB)
- Re: [TLS] Accepting that other SNI name types wil… Yuhong Bao
- Re: [TLS] Accepting that other SNI name types wil… Martin Thomson
- Re: [TLS] Accepting that other SNI name types wil… Fossati, Thomas (Nokia - GB)
- Re: [TLS] Accepting that other SNI name types wil… Fossati, Thomas (Nokia - GB)
- Re: [TLS] Accepting that other SNI name types wil… Richard Moore
- Re: [TLS] Accepting that other SNI name types wil… Hubert Kario
- Re: [TLS] Accepting that other SNI name types wil… Hubert Kario
- Re: [TLS] Accepting that other SNI name types wil… Martin Thomson
- Re: [TLS] Accepting that other SNI name types wil… Hubert Kario
- Re: [TLS] Accepting that other SNI name types wil… Richard Moore
- Re: [TLS] Accepting that other SNI name types wil… Hannes Tschofenig
- Re: [TLS] Accepting that other SNI name types wil… Blumenthal, Uri - 0553 - MITLL
- Re: [TLS] Accepting that other SNI name types wil… Adam Langley