Subject: [Trans] Certificate Transparency Newsletter - August 2015

From: Adam Eijdenberg <[email-masked]>
Date: Mon, 17 Aug 2015 17:24:26 +0000

(posted to [email-masked], [email-masked]
and [email-masked])

Hi CT watchers,

We wanted to put an update out to summarize what the Certificate
Transparency team at Google is working on as well as other efforts in
the space that we are aware of.  There are lots of other great
contributions taking place from other organizations and individuals so
we apologize for anything that we've missed and we'd also love to hear
more about them.

Standards work
==============
Achievements:
- Work continues on RFC6962-bis. Version 8 of the draft was published in
  July [1].
- IETF 93 was held in Prague in July, and the following CT presentations
  took place:
  - "trans" issues update [2] - Eran Messeri
  - CT Attack Model [3] - Steve Kent
  - draft-linus-trans-gossip-ct [4] - Daniel Kahn Gillmor and Linus
    Nordberg
  - CT for Binary Code [5] - Dacheng Zhang and Daniel Kahn Gillmor
  - Selective Logs [6] - Rich Salz
- New version of Gossip Internet Draft published in July [7].

Lookahead:
- We're very interested in exploring how we make it viable for a
  site-owner to be able to opt-in to requiring CT, ahead of any general
  browser-enforced deadlines.  We would welcome participation in helping
  define what this might look like in a manner that would work well for
  both browsers and site-owners.

[1] https://tools.ietf.org/html/draft-ietf-trans-rfc6962-bis-08
[2] https://www.ietf.org/proceedings/93/slides/slides-93-trans-3.pdf
[3] https://www.ietf.org/proceedings/93/slides/slides-93-trans-0.pdf
[4] https://www.ietf.org/proceedings/93/slides/slides-93-trans-2.pdf
[5] https://www.ietf.org/proceedings/93/slides/slides-93-trans-1.pdf
[6] https://www.ietf.org/proceedings/93/slides/slides-93-trans-4.pdf
[7] https://tools.ietf.org/html/draft-linus-trans-gossip-ct-02

Log servers
===========
Achievements:
- Symantec's log successfully completed compliance testing in August and
  the process has begun to move this into Chrome's trusted logs store
  [1].
- Testing is underway for one other log server implementation, Venafi.
- Design doc published for Google's open source log server [2].
- README updated with Quickstart instructions for building Google's open
  source log server [3].

Lookahead:
- Google is planning to update the open-source implementation to track
  the changes made in RFC6962-bis.

[1] http://www.certificate-transparency.org/known-logs
[2]
https://github.com/google/certificate-transparency/blob/master/docs/DesignDoc.md
[3] https://github.com/google/certificate-transparency/blob/master/README.md

Client implementations
======================
Achievements:
- Apple's new App Transport Security for iOS 9 and Mac OS X 10.11
  includes support for Certificate Transparency [1], although we're not
  sure exactly what it does yet.  Does anyone reading this have details to
share?
- Chrome 41, released in March of this year, began enforcing the CT
  requirement for all EV certificates issued after 1 Jan 2015.

Lookahead:
- Google is working with the Mozilla Foundation and a contractor to
  build a patch to contribute to Firefox to provide Certificate
  Transparency support in Firefox.
- Google is planning to launch a set of DNS servers to be able to handle
  inclusion proof checking over DNS. The primary motivation for doing so
  is so that a client (such as Chrome, or other browsers that wish to
  use this) can perform inclusion proof checks without directly
  revealing the browsing history of the user to any new parties,
  including Google. The intent is that the client will receive an
  inclusion proof by performing a DNS lookup for a TXT record for a
  specially crafted hostname, via the user's existing DNS resolver
  (typically an ISP) which in turn will resurse to eventually service
  the request from a Google DNS server.  In this manner the client is
  only revealing the leaf hashes they see (and thus the sites they
  visit) to their existing DNS resolver, which already (in practically
  all cases) has just serviced a DNS request for that same site and thus
  already knows their browsing history.
- Google is building out log mirrors for all logs included by Chrome,
  and the intent is that read-only requests from Chrome (for STHes, or
  inclusion-proofs (via the DNS mechanism above)) will be serviced by a
  log mirror, rather than the underlying logs.
- Google is building out Chrome support to include STH fetching, and to
  use the DNS inclusion proof method outlined above.  We intend to
  provide more information (including protocol details) as we make
  progress.
- Google is working with the OpenSSL community on adding experimental
  support into OpenSSL client for retrieving and validating all SCTs
  associated with a TLS connection [2].

[1]
https://developer.apple.com/library/prerelease/ios/technotes/App-Transport-Security-Technote/
[2]
https://github.com/aeijdenberg/openssl/blob/add_get_peer_scts/crypto/ct/README.md

Server implementations
======================
Achievements:
- haproxy [1], nginx [2] and Apache [3] support serving SCTs via TLS
  extensions (thanks to Janusz Dziemidowicz, Graham Edgecombe and Jeff
  Trawick respectively).
- New section added to Certificate Transparency site to demonstrate how
  to use these [4].
- (Apologies this is so specific to Google, but this was a big effort
  due to the scale of the organization/infrastructure) Google.com
  properties are now serving SCTs via the TLS Extension.

Lookahead:
- Google is looking at how to add SCT support to QUIC protocol, which is
  used to communicate between Chrome and many Google properties.

[1] https://cbonte.github.io/haproxy-dconv/configuration-1.6.html#5.1-crt
[2] https://github.com/grahamedgecombe/nginx-ct
[3] https://httpd.apache.org/docs/trunk/mod/mod_ssl_ct.html
[4] http://www.certificate-transparency.org/resources-for-site-owners

Monitors
========
Achievements:
- Both DigiCert [1] and Comodo [2] have implemented log monitors
  allowing interested parties to view certificates that are issued for
  a domain.
- Matt Palmer released an open-source Ruby framework for building your
  own monitor [3].

Lookahead:
- Google is also looking at adding a way to allow interested parties to
  search for and view certificates found in CT logs.
- Comodo is planning to release their monitor as open-source.

[1] https://www.digicert.com/certificate-monitoring/
[2] https://crt.sh/
[3] https://github.com/tobermorytech/certificate-transparency-monitor