Signature: Accept signatures with hs2019 algorithm

[obenland]

Follow-up to #1803 and depends on it for all tests to pass.

Proposed changes:

• Update get_signature_algorithm to check for hs2019 to identify algorithm.
• Add tests.

Other information:

• Have you written new tests for your changes, if applicable?

Testing instructions:

• The unit test should have it covered? 🤞

Changelog entry

• Automatically create a changelog entry from the details below.

Changelog Entry Details

Significance

• Patch
• Minor
• Major

Type

• Added - for new features
• Changed - for changes in existing functionality
• Deprecated - for soon-to-be removed features
• Removed - for now removed features
• Fixed - for any bug fixes
• Security - in case of vulnerabilities

Message

HTTP signatures using the hs2019 algorithm now get accepted without error.

[Copilot]

Pull Request Overview

This PR adds support for the hs2019 HTTP signature algorithm, updates the signature detection logic, and includes new tests plus a changelog entry.

• Introduce hs2019 case in get_signature_algorithm mapping to sha512
• Add unit tests for signature algorithm detection and full HTTP signature verification with hs2019
• Include a changelog entry for the new fix

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
tests/includes/class-test-signature.php	New data provider and tests for get_signature_algorithm and end-to-end hs2019 verification
includes/class-signature.php	Updated get_signature_algorithm to recognize hs2019
.github/changelog/1814-from-description	Added changelog entry for the hs2019 signature fix

Comments suppressed due to low confidence (2)

includes/class-signature.php:356

• Accessing $signature_block['algorithm'] without checking if the key exists can trigger a PHP notice for undefined index. Wrap it in isset() or use ! empty() to safely guard against missing keys.

if ( $signature_block['algorithm'] ) {

includes/class-signature.php:359

• The previous support for 'rsa-sha-512' was removed in this switch, causing that algorithm to fallback to the default 'sha256'. Consider re-adding a case 'rsa-sha-512': return 'sha512'; if you still intend to support it.

case 'hs2019':

[obenland]

@mediaformat It looks like I can't add you to the list of reviewers—would you still be able to give this a look and share any feedback you have?