There are multiple ways to password protect zip files. A user usually won't be able to tell whether the way used by their software is secure or not. The old way

There are multiple ways to password protect zip files. A user usually won't be able to tell whether the way used by their software is secure or not. The old way is insecure. http://math.ucr.edu/~mike/zipattacks.pdf http://math.ucr.edu/~mike/zipattacks.pdf https://github.com/hyc/fcrackzip https://github.com/hyc/fcrackzip The modern format uses PBKDF2 like many password hashing formats and needs to be attacked with john the ripper or hashcat.