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

[Kevin Driver]

On Fri, 6 Sep 2024 13:31:07 GMT, Viktor Klang <vklang at openjdk.org> wrote:

>> 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/82b8020a...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();

`os.flush()` requires catching an `IOException`. Do you suggest wrapping it in the `InvalidKeyException` already thrown by the method if it should occur? As you mention, it doesn't appear to be strictly necessary, and the javadoc for `toByteArray()` contains the following: 


Creates a newly allocated byte array. Its size is the current size of this output stream and the valid contents of the buffer have been copied into it.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20301#discussion_r1747548819