RFR: 8318756 Create better internal buffer for AEADs

[Daniel Jeliński]

On Tue, 28 Nov 2023 01:29:20 GMT, Anthony Scarpino <ascarpino at openjdk.org> wrote:

>> test/micro/org/openjdk/bench/javax/crypto/full/AESGCMBench.java line 43:
>> 
>>> 41:     AlgorithmParameterSpec getNewSpec() {
>>> 42:         iv_index = (iv_index + 1) % IV_MODULO;
>>> 43:         return new GCMParameterSpec(96, iv, iv_index, 12);
>> 
>> Can you also change tag length to 128 bits? TLS uses 128, and 128-bit tag generates a slightly different flamegraph.
>
> I'll see if I can do it cleanly. GCM spec defaults to 96bit and because CC20P1305 requires 96bit, it made the common code easier. I'm surprised you any differences which such a minor change.

FWIW, here's the relevant part of the flamegraphs:
![image](https://github.com/openjdk/jdk/assets/30433125/3a37921b-55d8-4f04-9d70-1b7b4ff9b7e2)
As you can see, the 128-bit tag is using a different intrinsic.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16487#discussion_r1407383930