Add hybrid KEM combiner

[rohanmahy]

The default ciphersuite for Chrome and in many servers is now. It used a KEM combiner combining ML-KEM-768 and X25519. Implementing the IETF recommended combiner and this specific combination would be useful.

[randombit]

PQ handshakes have been used by default since 3.7.0 (released Feb 2025), unless there is something else about this I'm not aware of?

$ ./botan tls_client gmail.com
Certificate validation status: Verified
Valid OCSP response for this server
Handshake complete, TLS v1.3
Negotiated ciphersuite AES_256_GCM_SHA384
Key exchange using x25519/ML-KEM-768
Session ID 69FBAAD58B3EC70DE33A509A8C14E21C50F055C262F8D4262DDF6528B2E176A4
Handshake complete

[rohanmahy]

Hi, I think it is just a documentation issue. It would be worth pointing this out in a read me in the kems directory Thanks, -rohan

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On Wed, May 6, 2026 at 10:58 PM Jack Lloyd ***@***.***> wrote: *randombit* left a comment (randombit/botan#5580) <#5580 (comment)> PQ handshakes have been used by default since 3.7.0 (released Feb 2025), unless there is something else about this I'm not aware of? $ ./botan tls_client gmail.com Certificate validation status: Verified Valid OCSP response for this server Handshake complete, TLS v1.3 Negotiated ciphersuite AES_256_GCM_SHA384 Key exchange using x25519/ML-KEM-768 Session ID 69FBAAD58B3EC70DE33A509A8C14E21C50F055C262F8D4262DDF6528B2E176A4 Handshake complete — Reply to this email directly, view it on GitHub <#5580 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AADSQPQ3BF3JFHBLIQTMH534ZORO5AVCNFSM6AAAAACYTUBOVSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DGOJSGA4TMNZZGM> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you authored the thread.Message ID: ***@***.***>