CLOUDFLARE has rolled out Automatic Key Exchange, an extension of its Automatic SSL/TLS system, to optimise origin handshakes in TLS 1.3 by learning which key-exchange algorithms each origin supports and prefers. Instead of always guessing X25519, Cloudflare now probes origins to determine their capabilities and leads with the most suitable algorithm on the first ClientHello. When possible, it prioritises post-quantum hybrid options such as X25519MLKEM768.
The result is a dramatic reduction in HelloRetryRequests (HRRs) and faster handshakes, with the company reporting a drop from about 52% HRR for origin connections to 3.7%, and a latency saving of more than 150 ms at the p90 for affected connections. Traffic also grew for post-quantum secured origins, rising from roughly 25 billion to 45 billion connections per day.
The approach is measured and automatic: Cloudflare scans origins to map per-origin capabilities, evaluates subdomains independently based on traffic, and then selects the strongest available option in a defined priority (post-quantum X25519MLKEM768 first, then classical X25519, P-256, P-384, or P-521). Compliance controls allow organisations to require post-quantum hybrids or FIPS-only algorithms, but Cloudflare warns that forcing post-quantum without universal support can break connections.
The rollout operates by default for TLS 1.3 origins and continues to grow, with ongoing monitoring of HRR rates and failure modes to prevent outages while enabling faster, quantum-secure origin connections where possible.