RFR: 8330842: Support AES CBC with Ciphertext Stealing (CTS) in SunPKCS11 [v6]

[Valerie Peng]

On Thu, 6 Jun 2024 22:21:57 GMT, Martin Balao <mbalao at openjdk.org> wrote:

>> src/jdk.crypto.cryptoki/share/classes/sun/security/pkcs11/P11Cipher.java line 1169:
>> 
>>> 1167:         }
>>> 1168:         if (ciphertextArr != null) {
>>> 1169:             ciphertextBuf = ByteBuffer.wrap(ciphertextArr);
>> 
>> Can we add a comment here to caution that position may be incorrect (since the offset is not passed to this call) and thus need to always supply an index for reading/writing values to the `ciphertextBuf`?
>
> It's not so much about position being incorrect —`convertCTSVariant` makes no assumptions about it, but could have reset position to the beginning of the last 2 blocks— but that `ciphertextBuf` bytes should not be modified except for the last 2 blocks. I'm okay with adding a comment but  I don't see any extension of the `convertCTSVariant` function that could be at risk of having to access anything other than the last 2 blocks.

True, the proposed change does not use the position of the `ciphertextBuf`. 
I'd just like some comment covering this since I find it strange that you call `ByteBuffer.wrap(cipherTextArr)` without the offset when the javadoc states that the position is set to 0. Maybe others may also wonder why. That's all.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18898#discussion_r1630528647