RFR: 8330842: Support AES CBC with Ciphertext Stealing (CTS) in SunPKCS11 [v4]

[Valerie Peng]

On Wed, 5 Jun 2024 14:21:57 GMT, Martin Balao <mbalao at openjdk.org> wrote:

>> What I like about this suggestion is that it allows unifying the repeated logic: the two blocks inside `if (encrypt)` and the corresponding `else` would become almost identical, allowing an additional abstraction. How about the following?
>> 
>> 
>>     private void convertCTSVariant(ByteBuffer ciphertextBuf,
>>             byte[] ciphertextArr, int end) {
>>         // [...]
>>         // [...] omitted code
>>         // [...]
>>         if (ciphertextBuf != null) {
>>             pad = pad == 0 ? blockSize : pad;
>>             if (encrypt) {
>>                 // .... pp[pp] ffff -> .... ffff pp[pp]
>>                 swapLastTwoBlocks(ciphertextBuf, end, pad, blockSize);
>>             } else {
>>                 // .... ffff pp[pp] -> .... pp[pp] ffff
>>                 swapLastTwoBlocks(ciphertextBuf, end, blockSize, pad);
>>             }
>>         }
>>     }
>> 
>>     private static void swapLastTwoBlocks(ByteBuffer buffer, int end,
>>             int prevBlockLen, int lastBlockLen) {
>>         // .... prevBlock lastBlock -> .... lastBlock prevBlock
>>         int prevBlockStart = end - prevBlockLen - lastBlockLen;
>>         byte[] prevBlockBackup = new byte[prevBlockLen];
>>         buffer.get(prevBlockStart, prevBlockBackup);
>>         buffer.put(prevBlockStart, buffer, end - lastBlockLen, lastBlockLen);
>>         buffer.put(end - prevBlockLen, prevBlockBackup);
>>     }
>
> Looks good to me.

Yes, I prefer this.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/18898#discussion_r1628246471