On Wed, 18 Mar 2026 12:54:40 GMT, Daniel Jeliński <[email protected]> wrote:

> Redo of #27343:
> 
>> TLS 1.3 changed the way it generates the FFDHE shared secret. In TLS 1.2, 
>> the leading zeroes in the shared secret were stripped, and in TLS 1.3 the 
>> leading zeroes are preserved.
> 
>> Thanks to the recent work in 
>> [JDK-8189441](https://bugs.openjdk.org/browse/JDK-8189441), we now have a 
>> new algorithm name Generic that can be used to generate a shared secret with 
>> the leading zeroes preserved.
> 
>> This PR changes the TLS 1.3 handshake to use the new algorithm name.
> 
> Compared to the original PR, a new system property 
> `jdk.tls.t13KeyDerivationAlgorithm` was introduced as a stop-gap solution for 
> deployments using third-party JCE providers that do not implement `Generic` 
> keys yet. Like other `jdk.tls` properties introduced for maintaining 
> compatibility, this property is not documented other than a mention in a 
> release note.
> 
> No new tests. The fix was verified with tlsfuzzer as described in JBS.

Changes look good.

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

Marked as reviewed by hchao (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/30296#pullrequestreview-4019663715

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