If you use an up-to-date browser or messaging app, there is a good chance some of your connections are already protected by post-quantum encryption. Here is where it is being used.
Web browsers
Google Chrome enabled a hybrid post-quantum key exchange by default on desktop in version 124 (April 2024), and switched to the final ML-KEM standard in version 131 (November 2024). Other browsers, including Microsoft Edge and Mozilla Firefox, have added support too. Large networks such as Cloudflare support it on their servers, so a growing share of web traffic is protected against harvest-now, decrypt-later attacks.
Messaging apps
In September 2023, Signal upgraded its protocol with PQXDH, adding a post-quantum key exchange to the way conversations start. In February 2024, Apple announced PQ3 for iMessage, which arrived with iOS 17.4 and also refreshes post-quantum keys during long conversations.
Remote access: OpenSSH
OpenSSH, the tool used to log in to most of the world’s servers, has used a hybrid post-quantum key exchange by default since version 9.0 in April 2022. Version 10.0, released in April 2025, made an ML-KEM-based hybrid the default.
What isn’t protected yet
These deployments mainly protect key exchange, which defends against harvest-now, decrypt-later attacks. Digital signatures and certificates, which prove that a website or software update is genuine, are harder to change: post-quantum signatures are larger, and the whole certificate ecosystem must agree on how to use them.
That transition is still in progress, but it is less urgent. A forged signature only matters once a quantum computer exists, while recorded traffic is at risk today.
What this means for you
- ◆Keep browsers, operating systems and apps up to date; that is how most people get quantum-safe protection.
- ◆Check whether your own websites, APIs and VPNs support hybrid key exchange.
- ◆Ask vendors when their products will support ML-KEM and ML-DSA.
task_altKey takeaways
- check_circleChrome, Signal, iMessage and OpenSSH already use post-quantum key exchange by default.
- check_circleKey exchange has moved first; signatures and certificates are still in progress.
- check_circleStaying up to date is the simplest way to benefit.