Automatic TLS 1.3 key exchange to origins
Cloudflare now automatically predicts and sends the preferred TLS 1.3 key agreement algorithm in the first ClientHello, eliminating unnecessary HelloRetryRequest round trips and improving handshake performance. The feature defaults to on for all zones and supports post-quantum X25519MLKEM768 hybrid key agreements when origins support them.
Cloudflare now takes the guesswork out of TLS 1.3 key agreement with your origins. Automatic key exchange predicts the preferred algorithm and sends its key share in the first ClientHello, helping avoid a HelloRetryRequest and one extra network round trip.
Automatic key exchange is on for all existing zones and on by default for new zones. When an origin supports both classical and post-quantum key agreements, Cloudflare prefers the post-quantum X25519MLKEM768 hybrid key agreement.
To change this behavior, go to SSL/TLS > Overview > Origin connection & post-quantum encryption. Turn off Automatic key exchange to stop automatic scans and preference updates. Turning it off does not change your compliance requirements.
Compliance requirements apply only to TLS 1.3 connections. The Post-quantum hybrid option requires hybrid post-quantum key agreements support on your origin server. The Federal Information Processing Standards (FIPS) option requires FIPS-compliant key agreements. Select both to require key agreements that satisfy both, or leave both unselected to allow all supported key agreements.
For requirements, configuration options, and rollout details, refer to Automatic key exchange to origins.
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