Remove dependency on cose for message signing

[cffls]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.61%. Comparing base (f2a9f2f) to head (98fac73).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #477      +/-   ##
==========================================
- Coverage   90.61%   90.61%   -0.01%     
==========================================
  Files          34       34              
  Lines        5157     5155       -2     
  Branches      782      781       -1     
==========================================
- Hits         4673     4671       -2     
  Misses        305      305              
  Partials      179      179              

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