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