RFR: 8331008: Implement JEP 478: Key Derivation Function API (Preview) [v24]

[Viktor Klang]

On Thu, 5 Sep 2024 23:17:32 GMT, Kevin Driver <kdriver at openjdk.org> wrote:

>> Introduce an API for Key Derivation Functions (KDFs), which are cryptographic algorithms for deriving additional keys from a secret key and other data. See [JEP 478](https://openjdk.org/jeps/478).
>> 
>> Work was begun in [another PR](https://github.com/openjdk/jdk/pull/18924).
>
> Kevin Driver has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 31 additional commits since the last revision:
> 
>  - Merge remote-tracking branch 'origin/master' into kdf-jep-wip
>    # Please enter a commit message to explain why this merge is necessary,
>    # especially if it merges an updated upstream into a topic branch.
>    #
>    # Lines starting with '#' will be ignored, and an empty message aborts
>    # the commit.
>  - several more review comments
>  - change impl class to use byte arrays rather than SecretKey objects where possible
>  - updated delayed provider selection javadoc
>  - review comments
>  - use a delegate record to hold the spi and provider
>  - assorted review comment changes
>  - another round of review comments
>  - consistency with wording for addIKM and addSalt
>  - another round of code review comments
>  - ... and 21 more: https://git.openjdk.org/jdk/compare/03a5b776...a35e98c9

src/java.base/share/classes/com/sun/crypto/provider/HkdfKeyDerivation.java line 259:

> 257:                     os.writeBytes(CipherCore.getKeyBytes(workItem));
> 258:                 }
> 259:                 return os.toByteArray();

I haven't found any specification indicating that flush is not required before toByteArray(), but it can't hurt right?

Suggestion:

                os.flush();
                return os.toByteArray();

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

PR Review Comment: https://git.openjdk.org/jdk/pull/20301#discussion_r1747132732