Fix Parsing Tagged Encrypted Data

[IlicMiljan]

Description of Changes

Replaced regex-based tag detection with a substr() based method for parsing tagged encrypted data, improving handling of special characters and formatting.

This fixes a bug where decryption was skipped due to special characters passed by base Cipher.

Related Issue

Resolves: #20

How Has This Been Tested?

The data was tested by encrypting and decrypting the base Cipher binary output.

Checklist

Please confirm the following:

• I have tested my changes and corrected any errors.
• I have documented my changes if necessary.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.34%. Comparing base (b80975b) to head (658e0b5).

Additional details and impacted files

@@             Coverage Diff              @@
##               main      #21      +/-   ##
============================================
+ Coverage     97.30%   97.34%   +0.04%     
- Complexity       84       86       +2     
============================================
  Files            22       22              
  Lines           260      264       +4     
============================================
+ Hits            253      257       +4     
  Misses            7        7              

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