RFR: 8314323: Implement JEP 527: TLS 1.3 Hybrid Key Exchange [v13]

[Weijun Wang]

On Fri, 5 Dec 2025 03:39:22 GMT, Hai-May Chao <hchao at openjdk.org> wrote:

>> Implement hybrid key exchange support for TLS 1.3 by adding three post-quantum hybrid named groups: X25519MLKEM768, SecP256r1MLKEM768, and SecP384r1MLKEM1024.
>> Please see [JEP 527](https://openjdk.org/jeps/527) for details about this change.
>
> Hai-May Chao has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 27 commits:
> 
>  - reapply changes after merge
>  - Merge
>  - backout conflict change in KeyShareExtension.java
>  - Updates with Weijun's comments
>  - Remove null check to not assume key is returned
>  - Updates with Brad's and Sean's comments
>  - Move Hybrid.java to sun.security.ssl
>  - Move DH.java to sun.security.ssl as DHasKEM.java
>  - Update names to uppercase
>  - Remove fallback in engineGeneratePublic
>  - ... and 17 more: https://git.openjdk.org/jdk/compare/7e91d34f...9c362c3e

src/java.base/share/classes/sun/security/ssl/KeyShareExtension.java line 731:

> 729:                         nps.getName() : null;
> 730:                 return algName != null && constraints.permits(
> 731:                         EnumSet.of(CryptoPrimitive.KEY_AGREEMENT),

Should this be `KEY_ENCAPSULATION`? How did we test this?

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PR Review Comment: https://git.openjdk.org/jdk/pull/27614#discussion_r2593205603