Re: [TLS] MUST <x> or what?
Eric Rescorla <ekr@rtfm.com> Thu, 27 August 2015 20:07 UTC
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From: Eric Rescorla <ekr@rtfm.com>
Date: Thu, 27 Aug 2015 13:06:43 -0700
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To: Martin Thomson <martin.thomson@gmail.com>
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Subject: Re: [TLS] MUST <x> or what?
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On Thu, Aug 27, 2015 at 1:06 PM, Martin Thomson <martin.thomson@gmail.com> wrote: > The statement I'd like to see is something like this... > > An endpoint that receives an illegal combination of "things" MAY choose to > treat that as a fatal error. > This seems totally reasonable. -Ekr > In this case, that means that if you include an ECDHE suite without an > ECDHE named_group, don't expect to have the connection succeed. > On Aug 27, 2015 12:51 PM, "Dave Garrett" <davemgarrett@gmail.com> wrote: > >> On Thursday, August 27, 2015 03:26:03 pm Eric Rescorla wrote: >> > My problem is precisely the conflation of offering with negotiating. >> The way that >> > many stacks work (for instance NSS) is that they negotiate the cipher >> suite >> > *first* and then they check for the presence or absence of the relevant >> extensions. >> > It's not clear to me that it's an improvement to require them to check >> for error >> > conditions that are not otherwise relevant. >> >> I'm not fundamentally opposed to having a hard requirement of an error >> check on negotiation, and basically a soft expectation on mere offering >> (SHOULD, MAY, or not mentioned; stern warning and shake of finger). That >> said, categorizing the cipher suites and just doing a quick check for which >> categories are there and what extensions came with it is not a very >> complicated requirement. I'm philosophically in the "do it right or explode >> so it can be found and fixed immediately" camp when it comes to very clear >> requirements like this, but I'm aware that this is sadly not always the >> dominant thought process. :| >> >> >> Dave >> >
- [TLS] MUST <x> or what? Martin Thomson
- Re: [TLS] MUST <x> or what? Eric Rescorla
- Re: [TLS] MUST <x> or what? Dave Garrett
- Re: [TLS] MUST <x> or what? Eric Rescorla
- Re: [TLS] MUST <x> or what? Dave Garrett
- Re: [TLS] MUST <x> or what? Martin Thomson
- Re: [TLS] MUST <x> or what? Viktor Dukhovni
- Re: [TLS] MUST <x> or what? Martin Thomson
- Re: [TLS] MUST <x> or what? Eric Rescorla
- Re: [TLS] MUST <x> or what? Eric Rescorla
- Re: [TLS] MUST <x> or what? Salz, Rich
- Re: [TLS] MUST <x> or what? Dave Garrett
- Re: [TLS] MUST <x> or what? Peter Gutmann
- Re: [TLS] MUST <x> or what? Peter Gutmann