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12 September 2012. Successor report:

7 September 2012

Certificate Transparency IETF Working Group

Topic discussion:

Related: Certificate Transparency certificate-transparency-draft:

Date: Fri, 7 Sep 2012 14:20:02 +0100
From: Ben Laurie <benl[at]>
To: sidr[at], therightkey[at]
Subject: [therightkey] Certificate Transparency WG

It has been suggested to me that the SIDR WG might be interested in Certificate Transparency and a possible BoF in Atlanta. Please send followup discussion to therightkey[at]

Here's an (updated) draft charter.

CT IETF WG Draft Charter

version 2


Specify mechanisms and techniques that allow Internet applications to monitor and verify the issuance of public X.509 certificates such that all issued certificates are available to applications, and each certificate seen by an application can be efficiently shown to be in the log of issued certificates. Furthermore, it should be possible to cryptographically verify the correct operation of the log.

Optionally, do the same for certificate revocations.

Problem Statement

Currently it is possible for any CA to issue a certificate for any purpose without any oversight. This has led to some high profile
mis-issuance of web certificates, such as by DigiNotar, a subsidiary of VASCO Data Security International, in July 2011:

The aim is to make it possible to detect such mis-issuance promptly through the use of a public log of all public issued certificates. Domain owners can then monitor this log and, upon detecting mis-issuance, take appropriate action.

This public log must also be able to efficiently demonstrate its own correct operation, rather than introducing yet another party that must be trusted into the equation.

Clients should also be able to efficiently verify that certificates they receive have indeed been entered into the public log.

For revocations, the aim would be similar: ensure that revocations are as expected, that clients can efficiently obtain the revocation status of a certificate and that the log is operating correctly.

Also, in both cases, the solution must be usable by browsers - this means that it cannot add any round trips to page fetches, and that any data transfers that are mandatory are of a reasonable size.

Existing Work

Certificate Transparency v2.1a

Spec and working code:
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