[jdk21u-dev] RFR: 8358159: Empty mode/padding in cipher transformations

[Varada M]

Hi all,

This pull request contains a backport of commit [3ff83ec4](https://github.com/openjdk/jdk/commit/3ff83ec49e561c44dd99508364b8ba068274b63a) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

The commit being backported was authored by Varada M on 10 Jun 2025 and was reviewed by Amit Kumar and Valerie Peng.

Thanks!

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Commit messages:
 - Backport 3ff83ec49e561c44dd99508364b8ba068274b63a

Changes: https://git.openjdk.org/jdk21u-dev/pull/1867/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1867&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8358159
  Stats: 68 lines in 2 files changed: 62 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1867.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1867/head:pull/1867

PR: https://git.openjdk.org/jdk21u-dev/pull/1867