Re: [TLS] Review of draft-wouters-tls-oob-pubkey-00.txt

Eric Rescorla <ekr@rtfm.com> Thu, 28 July 2011 14:13 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Thu, 28 Jul 2011 10:13:09 -0400
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To: Paul Wouters <paul@xelerance.com>
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Subject: Re: [TLS] Review of draft-wouters-tls-oob-pubkey-00.txt
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On Thu, Jul 28, 2011 at 10:06 AM, Paul Wouters <paul@xelerance.com>; wrote:
> On Thu, 28 Jul 2011, Eric Rescorla wrote:
>
>>> I'm interested in knowing why you consider it "clumsy". Especially
>>> because
>>> it closely follows the RFC 6066 section 6 extension for supressing of
>>> sending CA bundles with "trusted_ca_keys".  That apparent clumsiness
>>> passed WGLC and IESG.
>>
>> What's clumsy is:
>>
>> (1) It's not generic, even though generic caching is useful.
>
> 1) It's generic for allowing an arbitrary authentication method outside
> PKIX, which
>   generic caching does not, as it requires the TLS client to compute hashes
> over
>   PKIX information. In fact, the TLS client has to lie about already having
> the CA
>   bundle in order not to receive the PKIX blob.

As I said, you should *extend* cached-info.


> 2) generic caching is useful and it should also proceed through the IETF
> process.
>
>> (2) It doesn't support bare keys when the client doesn't know the key,
>> which
>> is also useful, if you want to use bare keys at all. In fact, it
>> doesn't even appear
>> to support cases where the client knows only the key hash, which is
>> common.
>
> That is a use case I had not considered. It is not hard to add support for
> that.
>
>> Whether it follows 6066 doesn't seem particularly relevant here, since we
>> have a
>> worked example of something better.
>
> "something better" only works with your other assumption of "sending and
> signing
> cruft in PKIX is fine". I strongly disagree with that.

I'm talking about cached-info here.

-Ekr