fix 19: add ts types and fix deprecated slice

[lenchv]

No description provided.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 89.47368% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 87.62%. Comparing base (455174b) to head (b3e603b).

Files	Patch %	Lines
lib/certs/CertificateRegistry.js	75.00%	1 Missing ⚠️
lib/encryption/DerValue.js	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #20      +/-   ##
==========================================
+ Coverage   87.40%   87.62%   +0.21%     
==========================================
  Files          16       17       +1     
  Lines         405      412       +7     
==========================================
+ Hits          354      361       +7     
  Misses         51       51              

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[lenchv]

fix #19