It looks like .bc file contents start with stuff that can uniquely identify the .bc file. This GitHub project https://github.com/secomba/boxcryptor-single-file-decryptor. The code in this project talks about 'bc01' has file signature. The .bc files that I created with BoxCryptor have
bc01 as the first four bytes. The same code also talks about
How does one make a bc02 file?
And is there any more stuff after the
bc01 that can help uniquely identify a .bc file regardless of the contents and regardless of BC settings?