Security Experts:

Chrome's Certificate Transparency to Become Mandatory

Google has announced its plans to make the Certificate Transparency policy in Chrome mandatory starting in October 2017.

Announced last week, the move will affect publicly trusted website certificates issued starting in October 2017, as they will have to comply with Chrome’s Certificate Transparency (CT) policy to be trusted by the browser. The announcement comes roughly three years after the open source framework for monitoring and auditing domain certificates was proposed by Google.

The framework has been already widely recognized and has become an Internet Engineering Task Force (IETF) open standard. Following the change, all certificates should be in compliance with the new requirement by 2020, considering the life-cycle of these certificates.

“The Chrome Team believes that the Certificate Transparency ecosystem has advanced sufficiently that October 2017 is an achievable and realistic goal for this requirement,” Google software engineer Ryan Sleevi said.

Certificate Authorities have already made investments in adopting the policy and, with Chrome requiring it in some cases, the overall security of the Internet has improved. “The use of Certificate Transparency has profoundly altered how browsers, site owners, and relying parties are able to detect and respond to misissuance, and importantly, gives new tools to mitigate the damage caused when a CA no longer complies with community expectations and browser programs,” Sleevi noted.

However, some CAs, browsers and site operators may encounter scenarios where the CT isn’t helpful, and they might have concerns over the October 2017 date. Those who do are encouraged to voice these concerns to IETF’s Public Notary Transparency WG (TRANS), so that they could be discussed and cataloged.

Google encourages interested parties to bring use cases to the light as soon as possible, during the next three months, although the aforementioned change won’t be made for another year, so that the appropriate solution for these issues would be found. “Such solutions may be though technical changes via the IETF or via policy means such as through the CA/Browser Forum or individual browsers’ root program requirements,” Sleevi notes.

The engineer also notes that Google will continue to communicate with CAs to ensure they are prepared, and says that the Chrome team will discuss a proposed new HTTP header at next month’s IETF meeting. The header should allow sites to opt-in to having CT requirements enforced in advance of the October 2017 deadline.

Some people, such as Doug Beattie, ‎VP product management at GlobalSign, have already commented on the announcement, revealing concerns over the implementation of the policy. According to him, it is important for both CAs and their customers to make educated decisions about issuing CT Qualified certificates. He also notes that knowing whether Chrome will warn of non-qualifying certs or will completely stop trusting them can help in this regard.

“Chrome's current policy only provides a clear statement of penalties for EV (no green banner) and does not amend/change that with a statement that all non-compliant certificates will not be trusted, as of October, 2017,” Beattie said. “Not showing the Green EV banner is a relatively small penalty for some customers while not trusting the certificate is much more severe,” he concluded.

Related: Google Adds Certificate Transparency Log for Untrusted CAs

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