Only allow supported pubKey types

[hendrikhofstadt]

Closes #2945

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.
• Wrote tests
• Updated relevant documentation (docs/)
• Added entries in PENDING.md with issue #
• rereviewed Files changed in the github PR explorer

---

For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #2949 into develop will increase coverage by 0.05%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           develop    #2949      +/-   ##
===========================================
+ Coverage    56.27%   56.32%   +0.05%     
===========================================
  Files          120      120              
  Lines         8411     8417       +6     
===========================================
+ Hits          4733     4741       +8     
+ Misses        3356     3354       -2     
  Partials       322      322

[cwgoes]

Tested ACK

[alexanderbez]

LGTM 👍