Support mlkem768x25519-sha256 algorithm with JDK 24

[mattrpav]

Description

Support ssh algorithm mlkem768x25519-sha256 using JDK provider

Motivation

OpenSSH 10 will default to mlkem768x25519-sha256, so it would be great for Apache Mina SSHD to support that algorithm as well from JDK 24 provider

ref: https://www.openssh.com/releasenotes.html

Alternatives considered

No response

Additional context

No response

[tomaswolf]

I don't understand. We do support this hybrid PQC algorithm since version 2.15.0, commit 38bb2c6.

[mattrpav]

I missed it! Thanks

[mattrpav]

Current impl requires bouncy castle.

JDK 24 will provide the algorithm as well

ref: https://seanjmullan.org/blog/2025/04/07/jdk24#:~:text=The%20SunJCE%20provider%20now%20supports,and%20ML%2DKEM%2D1024.

[tomaswolf]

I don't have the time to do that in the 2.x.0 versions. Maybe in the 3.0 branch, but don't hold your breath. (Needs multi-version jars since we still support Java 8, but I want to restructure bundles first before going multi-version.)

[mattrpav]

@tomaswolf sounds good. You may checkout the approach I did for ActiveMQ client library. We start with a source jar, extracting the contents to another module and then have only the few classes needed by another JDK sitting in the second module. Then that module can specify a different required source/target/release from the rest of the build.

See the activemq-client-jdk21 pom.xml here:
ref: https://github.com/apache/activemq/pull/1172/files#diff-9f5c9b6c95dfc3aee247ad8efc8950c5b1473614099c6a91f21a5c1fec9e015d/