Re: [TLS] Call for Adoption: TLS 1.3 Extension for Certificate-based Authentication with an External Pre-Shared Key

[Christopher Wood]

It looks like we have consensus to adopt this as an experimental WG
item. Russ, please submit the draft as
draft-ietf-tls-tls13-cert-with-extern-psk.

Thanks,
Chris, Joe, and Sean

On Sun, Feb 10, 2019 at 1:39 PM Christopher Wood
 wrote:
>
> Given the low amount of responses, we’re going to extend this adoption
> call for another two weeks. As a reminder, if you would like for this
> draft to become a WG document and you are willing to review it as it
> moves through the process, then please let the list know by 2359UTC
> 20180222. If you are opposed to this being a WG document, please say
> so (and say why).
>
> Thanks,
> Chris, Joe, and Sean
>
> On Fri, Feb 8, 2019 at 8:58 AM Eric Rescorla  wrote:
> >
> > I'd like to hear from some people who plan to implement and deploy this. 
> > Absent that, I'm not sure we should adopt it. Code points are free, so it 
> > doesn't need to be a TLS WG item unless the TLS WG and community are going 
> > to do substantial work on it.
> >
> > -Ekr
> >
> >
> > On Fri, Jan 25, 2019 at 10:12 AM Christopher Wood 
> >  wrote:
> >>
> >> At the TLS@IETF103 session, there was interest in adopting
> >> draft-housley-tls-tls13-cert-with-extern-psk as an experimental WG
> >> item, provided that it's limited to external PSKs with certificates
> >> for the initial handshake. This email is to determine whether there is
> >> WG consensus to adopt this draft (as is) as a WG item.
> >>
> >> If you would like for this draft to become a WG document and you are
> >> willing to review it as it moves through the process, then please let
> >> the list know by 2359UTC 20180208. If you are opposed to this being a
> >> WG document, please say so (and say why).
> >>
> >> Thanks,
> >> Chris, Joe and Sean
> >>
> >> ___
> >> TLS mailing list
> >> TLS@ietf.org
> >> https://www.ietf.org/mailman/listinfo/tls

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Re: [TLS] ct_compliant cached info field

[Rob Stradling]

Thanks EKR.

Done, in https://github.com/google/certificate-transparency-rfcs/pull/307

On 22/02/2019 14:51, Eric Rescorla wrote:
> That works for me
> 
> -Ekr
> 
> 
> On Fri, Feb 22, 2019 at 6:41 AM Rob Stradling  > wrote:
> 
> EKR, Martin,
> 
> Hi, and sorry for the long delay in replying.
> 
> This originated in [1] and was added to 6962-bis in [2].  The
> motivation
> was to provide a mechanism to permit a TLS server to avoid sending CT
> artifacts (SCTs, STHs, inclusion proofs) that it knows the TLS client
> already has or doesn't need, thereby reducing bytes on the wire for
> constrained and high-volume environments.
> 
> The approach envisaged by RFC7924 seems to be: "here's a list of TLS
> message fingerprints I've received previously; please don't send these
> exact messages to me again".  This works for stand-alone messages that
> contain one item, such as the server's Certificate message (which
> contains 1 server certificate chain).
> 
> However, in 6962-bis's case, SCTs and inclusion proofs are not
> stand-alone items; instead, they correspond to particular certificates.
> Each relevant TLS message will contain a TransItemList, which will
> probably contain at least a set of several SCTs; and whilst each SCT is
> static, the set (and the order within the set) is not.  Therefore, the
> approach of caching TLS messages by fingerprint didn't look like it
> would work for us.
> 
> We concluded that it would make more sense for the client to make a
> more
> high-level statement: "here's a list of certificate fingerprints that
> I've received previously and that I already regard as being
> CT-compliant".
> 
> This isn't an essential part of 6962-bis.  Other than Ben L's "Sounds
> like a good idea" comment in [1], I don't recall anyone commenting
> on it
> until EKR started this thread.
> 
> I propose to remove this cached-info mechanism from 6962-bis, if nobody
> objects.  (It could of course be revisited in some future document, if
> there's interest).
> 
> 
> [1] https://trac.ietf.org/trac/trans/ticket/111
> 
> [2] https://github.com/google/certificate-transparency-rfcs/pull/186
> 
> On 31/12/2018 14:36, Eric Rescorla wrote:
>  > + trans
>  >
>  > On Sun, Dec 30, 2018 at 10:06 PM Martin Thomson
> mailto:m...@lowentropy.net>
>  > >> wrote:
>  >
>  >
>  >     On Fri, Dec 28, 2018, at 04:58, Eric Rescorla wrote:
>  >      > Please take a look at
>  >      >
>  >
> https://tools.ietf.org/html/draft-ietf-trans-rfc6962-bis-30#section-6.5
>  >
>  >     At a minimum, this would seem to update cached_info.
>  >
>  >     There's not a lot of meat on this text.  It seems to be
> saying that
>  >     if you are providing transparency_info, then you can provide a
>  >     certificate other than any of the certificates that the client
>  >     believes to be CT compliant.  Also, you don't provide
> "x509_sct_v2"
>  >     or "precert_sct_v2" in transparency_info.
>  >
>  >     How is the client then able to determine that this new
> certificate
>  >     is CT compliant?  Using  "inclusion_proof_v2" and
>  >     "signed_tree_head_v2" (or one or other)?  If so, the text doesn't
>  >     point in that direction.
>  >
>  >     There's a lot of "why" missing in this document.  Why would a
> client
>  >     choose to indicate "ct_compliant"?  Why is cached_info being
>  >     extended in this way?
>  >
>  >     I might guess that the reason here is that the draft aims to
> avoid
>  >     including information that might change over time, which would
>  >     render caches invalid.  Isn't that motivation to recommend an SCT
>  >     over an STH?
>  >
>  >     Separately, why does this establish a new registry for signature
>  >     schemes?  It is obviously trying to keep TLS compatibility,
> based on
>  >     the codepoints, but forking the registry is a great way to create
>  >     problems.
> 
> -- 
> Rob Stradling
> Senior Research & Development Scientist
> Email: r...@sectigo.com 
> 

-- 
Rob Stradling
Senior Research & Development Scientist
Email: r...@sectigo.com
Bradford, UK
Office: +441274024707
Sectigo Limited

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