RFR: 8314323: TLS 1.3 Hybrid Key Exchange

[Artur Barashev]

On Thu, 2 Oct 2025 22:52:49 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.

src/java.base/share/classes/com/sun/crypto/provider/DH.java line 248:

> 246:                 "XDH", "XDH", NamedParameterSpec.X25519),
> 247: 
> 248:         X448(56, 56,

Why do we need `X448` and `P521`?

src/java.base/share/classes/sun/security/util/Hybrid.java line 100:

> 98:     private static KEM getKEM(String name) throws NoSuchAlgorithmException {
> 99:         if (name.startsWith("secp") || name.equals("X25519") ||
> 100:                 name.equals("X448")) {

Do we need `X448` here? Also, please provide a comment for this method with functionality description.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/27614#discussion_r2402639954
PR Review Comment: https://git.openjdk.org/jdk/pull/27614#discussion_r2402633190