Every time Cloudflare opens a new TLS 1.3 connection to an origin server, we have to guess the key agreement algorithm. Guess wrong, and a Hello Retry Request costs an extra round trip. For years, our guess was X25519, but that was suboptimal for roughly 30% of origins.

Today we're announcing Automatic Key Exchange, an extension of Automatic SSL/TLS that probes each origin to learn its preferred algorithms, then leads with that algorithm on the first try, preferring the post-quantum hybrid X25519 MLKEM768. Hello Retry Requests fell from roughly 52% to 3.7%, cutting more than 150 ms off handshake latency at p90. Hundreds of thousands of domains now have post-quantum origin connections with no manual configuration.

That second part matters more. Adversaries are recording encrypted traffic now to decrypt later (harvest-now, decrypt-later). Cloudflare is sprinting to make the Internet quantum-secure by 2029, the year experts estimate classical encryption could be breached: Q-Day. Meeting that deadline can't depend on millions of operators becoming cryptographers. It has to be automatic.

Until today, preferring post-quantum connections required a manual setting. But today it’s just … automatic!