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

[Xue-Lei Andrew Fan]

On Wed, 15 Oct 2025 06:48:50 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 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/sun/security/util/Hybrid.java line 230:

> 228:             }
> 229: 
> 230:             throw new InvalidKeySpecException(keySpec.toString());

Please check null keySpec, and  `throw new InvalidKeySpecException("keySpec must not be null")`.

For non-null keySpec, I may use:
`throw new InvalidKeySpecException(keySpec.getClass().getName() + " not supported.");
`

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PR Review Comment: https://git.openjdk.org/jdk/pull/27614#discussion_r2464296380