As part of our ongoing commitment to ensuring users’ security, Google is reducing the maximum allowed lifetimes of TLS certificates.
Beginning with Chrome 85, TLS server certificates issued on or after 2020-09-01 00:00:00 UTC will be required to have a validity period of 398 days or less. This will only apply to TLS server certificates from CAs that are trusted in a default installation of Google Chrome, commonly known as “publicly trusted CAs”, and will not apply to locally-operated CAs that have been manually configured.
Certificates that do not comply with this requirement will not work, and may cause webpages to fail to load or to render incorrectly.
If a certificate that does not comply with this requirement is issued by a CA trusted in a default installation of Google Chrome, this will be treated as a failure to comply with the security policies necessary to being a trusted CA, and may result in the removal of trust of that CA’s certificates.
- A certificate will be impacted by this restriction if either the notBefore of the certificate is on or after 2020-09-01 00:00:00 UTC, or if the first precertificate logged by the CA to a Certificate Transparency Log that is qualified at time of issuance is on or after this date.
- The validity period of a certificate is defined within RFC 5280, Section 126.96.36.199, as “the period of time from notBefore through notAfter, inclusive.”
- 398 days is measured with a day being equal to 86,400 seconds. Any time greater than this indicates an additional day of validity.
- To avoid the risk of misissuance, such as due to leap seconds or CA-configured randomization, CAs SHOULD issue such server certificates with validity periods of 397 days or less.
Frequently Asked Questions
- Why is Chrome making this change?
- Shortening certificate lifetimes protects users by reducing the impact of compromised keys, and by speeding up the replacement of insecure technologies and practices across the web. Key compromises and the discovery of internet security weaknesses are common events that can lead to real-world harm, and the web’s users should be better protected against them.
- Does this apply to locally-operated CAs, such as those used within enterprises that use enterprise-configured configured CAs?
- No. This only applies to the set of CAs that are trusted by default by Google Chrome, and not CAs that are operated by an enterprise and that have no certification paths to CAs that are trusted by default.
- Is there an enterprise policy to disable this enforcement?
- No. These changes are transparent and do not offer an enterprise control to override, as they only apply to so-called “publicly trusted” CAs. Enterprises that wish to have certificates with validity periods longer than 398 days may do so by using a locally-operated CA that does not have any certification paths up to a publicly trusted CA.
- Does this mean I have to replace my existing certificates?
- No. This requirement only applies to new certificate issuance on or after 2020-09-01 00:00:00 UTC. Existing certificates whose validity period exceeds 398 days will continue to work, while new certificates must comply with these new requirements, such as when they are renewed or replaced.
- Will this make certificates more expensive?
- As with past changes to the maximum certificate lifetimes, many CAs have committed to providing additional certificates, as needed by the shortened maximum lifetime, at no additional cost.
- What will happen if a certificate is issued that does not meet these requirements?
- Google Chrome will reject such certificates as having too long a validity period, consistent with existing validity-period based enforcement. Additionally, such certificates will be treated as a critical security failure by the CA, and may result in further action taken on the CA that may affect how current or future certificates from that CA function. Chromium-based browsers will have this enforcement enabled by default, and will need to modify the source to disable this.
- What are other browsers doing?
Apple previously announced this change for versions of iOS, iPadOS, macOS, tvOS, and watchOS, as documented at https://support.apple.com/en-us/HT211025, which will apply to all applications, and not just those of Safari. This certificate lifetime requirement is fully interoperable with Apple’s requirements.
Microsoft, Mozilla, Opera, and 360 have previously indicated their support for these requirements, although have not yet made announcements at the time of this post (2020-06-22). Other browsers, including those browsers based on Chromium, may provide additional guidance or clarification.