[jdk21u-dev] RFR: 8322971: KEM.getInstance() should check if a 3rd-party security provider is signed

[Andrew John Hughes]

Hi all,

This pull request contains a clean backport of commit [9fd855ed](https://github.com/openjdk/jdk/commit/9fd855ed477bb0849ce5c774854844deec0f4c6b) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

The commit being backported was authored by Weijun Wang on 11 Jan 2024 and was reviewed by Sean Mullan and Valerie Peng.

Tests in `test/jdk/javax/crypto/KEM` and `test/jdk/com/sun/crypto/provider/DHKEM` all passed on the patched build.

The change jumped 21u and [is already in 17u](https://git.openjdk.org/jdk17u/commit/e49367bba1733eaad374c152e04e2af322956466), thanks to the 17.0.0.1 RI, so we should get it fixed here too.

Thanks!

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

Commit messages:
 - Backport 9fd855ed477bb0849ce5c774854844deec0f4c6b

Changes: https://git.openjdk.org/jdk21u-dev/pull/893/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=893&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8322971
  Stats: 119 lines in 4 files changed: 74 ins; 29 del; 16 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/893.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/893/head:pull/893

PR: https://git.openjdk.org/jdk21u-dev/pull/893