Fix typos for DSA

[sfod]

Issue #, if available:

There's a typo in code determining DSA keys.

Description of changes:

Fix the typo, add tests.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.81%. Comparing base (9cf142c) to head (524733f).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #768      +/-   ##
==========================================
+ Coverage   78.76%   78.81%   +0.04%     
==========================================
  Files          30       30              
  Lines        6410     6410              
==========================================
+ Hits         5049     5052       +3     
+ Misses       1361     1358       -3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.