There seems to be package fcrackzip included in Trisquel. It's a Free/Fast
Zip Password Cracker. Its man page includes:
*** ZIP PASSWORD BASICS ***
Have you ever mis-typed a password for unzip? Unzip reacted pretty fast with
'incorrect password', without decrypting the whole file. While the encryption
algorithm used by zip is relatively secure, PK made cracking easy by
providing hooks for very fast password-checking, directly in the zip file.
I personally wouldn't trust anything else besides GPG, that's pretty much
what Snowden said.
