Minor fixes on key parsing, typing and additional tests

[covert-encryption]

No description provided.

[codecov]

Codecov Report

Merging #76 (04ba7a9) into main (ef35271) will increase coverage by 1.20%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #76      +/-   ##
==========================================
+ Coverage   73.26%   74.47%   +1.20%     
==========================================
  Files          23       23              
  Lines        2173     2174       +1     
  Branches      510      510              
==========================================
+ Hits         1592     1619      +27     
+ Misses        457      432      -25     
+ Partials      124      123       -1     

Impacted Files	Coverage Δ
covert/pubkey.py	87.36% <100.00%> (+13.82%)	⬆️

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[covert-encryption]

Affects #71 but that still needs more work.