Thank you for the comments. I'll fix most of them - responses inline for
the rest:
On 07/07/2023 17:38, Eric Rescorla wrote:
S 3.1.2.
7. Order the list by the date each certificate was included in the
CCADB, breaking ties with the lexicographic ordering of the
SHA256 certificate fingerprint.
Would it be simpler to just sort by the hash?
Possibly a premature optimization, but I was thinking that if a new
version only included new certificates, it'd be nice to only have to
append the new data to the existing dictionaries. I haven't yet worked
out if that's actually going to deliver anything useful though.
1. If so, replace the opaque cert_data member of
CertificateEntry with its adjusted three byte identifier and
copy the CertificateEntry structure with corrected lengths to
the output.
It seems like this is not injective in the face of certificates
whose length is greater than or equal to 0xff0000. That's probably
not a problem, but I think you should make it clear and have some
way to manage it.
If the length is corrected, isn't the only risk a collision with a
certificate which is exactly three bytes and starts with 0xff?
S 3.2.1
How much value are you getting from the CT logs? It seems like
additional complexity. I agree with your comment about having
this submitted to CCADB.
It seemed the fairest repeatable way to check whether a CA was offering
certificates to WebPKI clients without having to write a lot of emails.
I agree its not desirable to keep as a dependency in the long run.
S 5.1.
ISTM that there are plenty of code points available.
Thanks!
Best,
Dennis
On Thu, Jul 6, 2023 at 3:18 PM Dennis Jackson
<ietf=40dennis-jackson...@dmarc.ietf.org> wrote:
Hi all,
I've submitted the draft below that describes a new TLS certificate
compression scheme that I'm calling 'Abridged Certs' for now. The
aim is
to deliver excellent compression for existing classical certificate
chains and smooth the transition to PQ certificate chains by
eliminating
the root and intermediate certificates from the bytes on the wire. It
uses a shared dictionary constructed from the CA certificates
listed in
the CCADB [1] and the associated extensions used in end entity
certificates.
Abridged Certs compresses the median certificate chain from ~4000 to
~1000 bytes based on a sample from the Tranco Top 100k. This beats
traditional TLS certificate compression which produces a median of
~3200
bytes when used alone and ~1400 bytes when combined with the outright
removal of CA certificates from the certificate chain. The draft
includes a more detailed evaluation.
There were a few other key considerations. This draft doesn't impact
trust decisions, require trust in the certificates in the shared
dictionary or involve extra error handling. Nor does the draft favor
popular CAs or websites due to the construction of the shared
dictionary. Finally, most browsers already ship with a complete
list of
trusted intermediate and root certificates that this draft reuses to
reduce the client storage footprint to a few kilobytes.
I would love to get feedback from the working group on whether the
draft
is worth developing further.
For those interested, a few issues are tagged DISCUSS in the body
of the
draft, including arrangements for deploying new versions with updated
dictionaries and the tradeoff between equitable CA treatment and the
disk space required on servers (currently 3MB).
Best,
Dennis
[1] Mozilla operates the Common CA Database on behalf of Apple,
Microsoft, Google and other members.
On 06/07/2023 23:11, internet-dra...@ietf.org wrote:
> A new version of I-D, draft-jackson-tls-cert-abridge-00.txt
> has been successfully submitted by Dennis Jackson and posted to the
> IETF repository.
>
> Name: draft-jackson-tls-cert-abridge
> Revision: 00
> Title: Abridged Compression for WebPKI Certificates
> Document date: 2023-07-06
> Group: Individual Submission
> Pages: 19
> URL:
https://www.ietf.org/archive/id/draft-jackson-tls-cert-abridge-00.txt
> Status:
https://datatracker.ietf.org/doc/draft-jackson-tls-cert-abridge/
> Html:
https://www.ietf.org/archive/id/draft-jackson-tls-cert-abridge-00.html
> Htmlized:
https://datatracker.ietf.org/doc/html/draft-jackson-tls-cert-abridge
>
>
> Abstract:
> This draft defines a new TLS Certificate Compression scheme
which
> uses a shared dictionary of root and intermediate WebPKI
> certificates. The scheme smooths the transition to post-quantum
> certificates by eliminating the root and intermediate
certificates
> from the TLS certificate chain without impacting trust
negotiation.
> It also delivers better compression than alternative
proposals whilst
> ensuring fair treatment for both CAs and website operators.
It may
> also be useful in other applications which store certificate
chains,
> e.g. Certificate Transparency logs.
>
>
>
>
> The IETF Secretariat
>
>
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