Certificate Transparency Enforcement in Chrome and CT Day in London

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Devon O'Brien

May 1, 2018, 7:18:50 PM5/1/18
to Certificate Transparency Policy

Hello ct-policy,

We’re excited to announce that we have now passed the April 30, 2018 Certificate Transparency enforcement deadline for Google Chrome. This day has been a long time in the making and we’d like to take a moment to explain this milestone in greater detail.

In version 68, Chrome will start enforcing that all TLS server certificates issued after April 30, 2018 comply with the Chromium CT Policy in order to be trusted. Main page connections that are served over a non-compliant connection will display a full page warning, and sub-resources served over a non-compliant connection will fail to load.

CT enforcement will start with Chrome 68, appearing on Chrome Canary shortly and then progressing through Dev, Beta, and finally Stable according to the dates below. Despite some reports that users will begin to see these warnings starting today, sites will not be impacted until the following dates depending on the release channel of Chrome being used. Due to timing variance in the Canary and Dev channels, we’ve only listed the relevant dates for 68 Beta and 68 Stable:

Release Channel

Approximate Date

Chrome 67 and earlier

Not Impacted

Chrome 68 Beta

~June 7, 2018

Chrome 68 Stable

~July 24, 2018

Please refer to the Chromium Release Calendar for more detailed information on upcoming Chrome release dates.

Site Operators and CAs that wish to test newly-issued certificates for compliance can do so beginning with Chrome 67. Site Operators that wish to simply check if their certificate is CT compliant can open Developer Tools. The Security panel will provide details about the connection and certificate, including whether or not the connection and certificate appropriately support Certificate Transparency. Alternatively, for Site Operators that would like to test non-compliant certificates being actively blocked, they can do so via command-line flags. To test, launch Chrome with the following command-line flags:

--enable-features=”EnforceCTForNewCerts<EnforceCTTrial” --force-fieldtrials=”EnforceCTTrial/Group1” --force-fieldtrial-params=”EnforceCTTrial.Group1:date/1525132800

As an alternative to testing directly in the browser, Site Operators can use services such as Hardenize to inspect and test their security configuration, including whether or not the servers and certificates are appropriately configured to support Certificate Transparency.

In order to build upon the lessons learned leading up to CT enforcement, we are planning a one day event at Google London that will take place on June 4, 2018. This is the day before the June CA/Browser Forum Face to Face takes place, also in London. We know that many of you will be attending the upcoming CA/Browser meeting who have not been able to attend any of our previous CT events and would like to invite you to this event, which is focused on CT integration and implementation topics for both today’s enforcement deadline as well as long-term strategies for sustained CT support.

Here are some topics we’re looking to cover during this event:

  • Hands on with Trillian Deployment

  • Time-sharded CT Logs: Why and How

  • CA Software Integration with CT

  • The Lifecycle of a CT Log

If you are interested in attending, please fill out the below form link to RSVP. Space is limited, so please await confirmation before making arrangements to attend.


Corey Bonnell

May 3, 2018, 2:34:00 PM5/3/18
to Certificate Transparency Policy
 Hello Devon,
Thank you for the update regarding CT enforcement in Google Chrome and the information on the next scheduled CT Day.

Unfortunately, no one from our team (Trustwave) is able to attend in-person. Will remote participation be an option?

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