Back in 2016, Google began quietly testing a new layer of encryption in Chrome — one designed to withstand a threat that didn’t exist yet: a working quantum computer. Google, Microsoft, IBM and others were racing to build quantum computers that could dramatically increase computing power, and Google’s response was to start preparing Chrome for the cryptographic fallout years in advance.
A sufficiently powerful quantum computer would eventually be able to break the encryption methods that secure the web today. That’s the challenge Google set out to test with an early experimental key-exchange algorithm.
From Google’s original announcement:
However, a hypothetical, future quantum computer would be able to retrospectively decrypt any internet communication that was recorded today, and many types of information need to remain confidential for decades. Thus even the possibility of a future quantum computer is something that we should be thinking about today.
This experiment is currently enabled in Chrome Canary and you can tell whether it’s being used by opening the recently introduced Security Panel and looking for “CECPQ1”, for example on https://play.google.com/store. Not all Google domains will have it enabled and the experiment may appear and disappear a few times if any issues are found.
Update: where things stand today
That 2016 experiment, known as CECPQ1, turned out to be just the first step. Google refined the approach with a successor (CECPQ2) before moving to the finalized industry standard. In April 2024, Chrome 124 began enabling a hybrid post-quantum key exchange (X25519Kyber768) by default for all users, not just those testing Canary builds. After NIST formally standardized the underlying algorithm as ML-KEM in FIPS 203 (August 2024), Chrome 131 switched to the standardized version, X25519MLKEM768, that November. By Chrome 138 in 2025, the feature could no longer be disabled, and both Chrome and Firefox now ship it by default — Cloudflare measured roughly 38% of HTTPS traffic already using hybrid post-quantum key exchange as of March 2025.
In short, what began as a niche experiment for security researchers in 2016 is now quietly protecting ordinary browsing sessions by default, with no action required from users.
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