Re: [TLS] WGLC for draft-ietf-tls-exported-authenticator

[Nick Sullivan <[e-mail]>]

Thanks all for the comments on the draft. Let me try to summarize the
comments and propose next steps.

Tim Hollebeek had a comment about 0 as the separator. I generally don’t
think this is a big issue, and prefer 0 because it is a natural way to
terminate a string. If anyone strongly disagrees, please reply to the list.

Roelof duToit raised a question about middlebox interoperability,
specifically that the exporters will not match if the TLS connection is not
end-to-end. There was a subsequent discussion about where to signal this
property. Martin Thomson suggested a signaling mechanism at the application
layer (https://github.com/httpwg/http-extensions/issues/617) and Eric
Rescorla suggested that the fact that this could cause CertificateVerify
failures should be called out in the document. I'll put a PR together to
add some helpful text around debugging CertificateVerify failures to
address Eric's suggestion.

Ben Kaduk had three points:
- The certificate_request_context is prone to collisions with
post-handshake authentication and there are different spaces for the server
and client context values. He suggested some text in Section 3 and maybe
more explanation in Section 5.2 as well. I’ll put together a PR for this.
- Section 4.1 talks of the length of the exporter value in terms of the
length of the
TLS PRF hash, adding that cipher suites not using TLS PRF have to define a
hash function, but TLS 1.3 ciphersuites do not use the TLS PRF. I’ll put
together a PR to clarify the text around this clarifying that for TLS 1.3
cipher suites, the HDKF hash is what is meant.
- The “signature_algorithms_cert” extension was not incorporated into the
draft. I’ll put together a PR for 4.2.1., 4.2.2. and 5.1. to incorporate
this extension.

I'll have the proposed changes for the above comments ready next week.

There were also some uncontroversial suggestions that I propose merging:
https://github.com/tlswg/tls-exported-authenticator/pull/21
https://github.com/tlswg/tls-exported-authenticator/pull/22
https://github.com/tlswg/tls-exported-authenticator/pull/23
https://github.com/tlswg/tls-exported-authenticator/pull/24


Nick


On Thu, May 3, 2018 at 1:16 PM Nick Sullivan <[e-mail]>
wrote:

> Does anyone have any comments about the draft, criticisms, or votes of
> support?
>
> Nick
>
>
> On Thu, May 3, 2018 at 1:12 PM Sean Turner <[e-mail]> wrote:
>
>>
>>
>> > On Apr 21, 2018, at 10:25, Sean Turner <[e-mail]> wrote:
>> >
>> >
>> >> On Apr 19, 2018, at 16:32, Sean Turner <[e-mail]> wrote:
>> >>
>> >> All,
>> >>
>> >> This is the working group last call for the "Exported Authenticators
>> in TLS" draft available at
>> https://datatracker.ietf.org/doc/draft-ietf-tls-exported-authenticator/.
>> Please review the document and send your comments to the list by 2359 UTC
>> on 4 April 2018.
>> >
>> > … 4 May 2018 ...
>>
>> Just a reminder the WGLC ends tomorrow.
>>
>> spt
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>