RFR: 8314323: Implement JEP 527: TLS 1.3 Hybrid Key Exchange [v6]

[Hai-May Chao]

On Wed, 15 Oct 2025 14:25:50 GMT, Artur Barashev <abarashev at openjdk.org> wrote:

>> Hai-May Chao has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Revert changes to UseStrongDHSizes test as ffdhe6144/8192 added back
>>  - Updated comment in ServerHello and hybrid to upper-case in NamedGroup
>
> src/java.base/share/classes/java/security/spec/NamedParameterSpec.java line 141:
> 
>> 139:      * @since 26
>> 140:      */
>> 141:     public static final NamedParameterSpec SecP384r1MLKEM1024
> 
> Nit: Let's make these all upper-case as well to keep things consistent across files.

We don’t need to make the `NamedParameterSpec` instances for hybrid named groups public, as they do not need to be exposed through the public API. So change is made to deine them in `Hybrid.java` now, and to keep all hybrid-related constants in one place. Their names are written in all uppercase: `X25519_MLKEM768`, `SECP256R1_MLKEM768`, and `SECP384R1_MLKEM1024`. We use a two-part naming style (for left and right algorithm).

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PR Review Comment: https://git.openjdk.org/jdk/pull/27614#discussion_r2505710074