RFR: 8330842: Support AES CBC with Ciphertext Stealing (CTS) in SunPKCS11 [v3]

[Valerie Peng]

On Mon, 3 Jun 2024 22:26:04 GMT, Martin Balao <mbalao at openjdk.org> wrote:

>> src/jdk.crypto.cryptoki/share/classes/sun/security/pkcs11/P11Cipher.java line 621:
>> 
>>> 619:                     int flushFromPadBuffer;
>>> 620:                     int fillLen = getBytesToCompleteBlock(padBufferLen);
>>> 621:                     if (dataForP11Update >= padBufferLen + fillLen) {
>> 
>> Maybe use `if (inLen >= fillLen)` ?
>
> `dataForP11Update >= padBufferLen + fillLen` is not the same as `inLen >= fillLen` (the equivalent would be `inLen - newPadBufferLen >= fillLen`, but I personally find the proposed condition more clear). We will flush the entire `padBuffer` only if there are enough bytes in `inLen` to fill `padBuffer` with whatever we need (0 or more bytes) and fulfill the new buffering requirement. Regarding `fillLen > 0`, that is not strictly needed to flush the entire `padBuffer`. If we are buffering 3 blocks (e.g. for NSS), we may have 1 block buffered in `padBuffer` and `fillLen == 0` (no need to borrow to complete `padBuffer` to a multiple of a block size).

I see, thanks for the explanation.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18898#discussion_r1626829385