RFR: 8358159: Empty mode/padding in cipher transformations [v3]

[Valerie Peng]

On Wed, 4 Jun 2025 18:06:33 GMT, Valerie Peng <valeriep at openjdk.org> wrote:

>> Varada M has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   whitespace error fix
>
> src/java.base/share/classes/javax/crypto/Cipher.java line 393:
> 
>> 391:             this.suffix = suffix.toUpperCase(Locale.ENGLISH);
>> 392:             this.mode = ((mode == null) || mode.isEmpty()) ? null : mode;
>> 393:             this.pad = ((pad == null) || pad.isEmpty()) ? null : pad;
> 
> Thanks for reporting and fixing this issue. 
> Since this is an internal class used solely inside `Cipher` class, instead of changing the empty string to null inside the `Transform` constuctor, we can do that before calling `Transform` constructor. Also if one of `mode` or `pad` is empty, then maybe we don't need all 4 `Transform`s.

For exampl, line 457, 458, we can do something like:

        String mode = (parts[1].length() == 0 ? null : parts[1]);
        String pad = (parts[2].length() == 0 ? null : parts[2]);

When populating the `list `(after line 467), we can skip the Tranform if the required component is missing, e.g.

            List<Transform> list = new ArrayList<>(4);
            if ((mode != null) && (pad != null)) {
                list.add(new Transform(alg, "/" + mode + "/" + pad, null, null));
            }

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PR Review Comment: https://git.openjdk.org/jdk/pull/25547#discussion_r2127172956