RFR: 8353578: Refactor existing usage of internal HKDF impl to use the KDF API

[Weijun Wang]

On Wed, 2 Apr 2025 21:43:19 GMT, Valerie Peng <valeriep at openjdk.org> wrote:

> This PR removes the internal JSSE HKDF impl and changes to use the KDF API for the HKDF support from JCA/JCE providers.
> 
> This is just code refactoring. Known-answer regression test for the internal JSSE HKDF impl is removed as the test vectors are already covered by the HKDF impl in SunJCE provider.
> 
> Thanks in advance for the review~

src/java.base/share/classes/sun/security/ssl/KAKeyDerivation.java line 120:

> 118:                 SecretKey earlySecret = hkdf.deriveKey("TlsEarlySecret",
> 119:                         HKDFParameterSpec.ofExtract().addSalt(zeros)
> 120:                         .addIKM(ikm).extractOnly());

Maybe no need for `addSalt(zeros)`. I remember salt is by default zeros for HKDF.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24393#discussion_r2025733194