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Fcrackzip

A braindead program for cracking encrypted ZIP archives. Forked from http://oldhome.schmorp.de/marc/fcrackzip.html

Install / Use

/learn @hyc/Fcrackzip
About this skill

Quality Score

0/100

Supported Platforms

Universal

README

Original README text follows below. This archive was originally copied from http://oldhome.schmorp.de/marc/fcrackzip.html

The original program spawns an external unzip binary when checking password guesses (with the -u option). This is extremely slow, so I've modified the code to use libzip instead. This speeds up guessing by over a factor of 1000 on my laptop, even with SSD.

libzip is available on mst Linux distros. I believe this program is largely obsoleted now if you have John the Ripper with the Jumbo patch. In john-1.7.9-jumbo-7 you can just use zip2john and then run john.

-- Howard Chu hyc@symas.com

Original below

See fcrackzip.txt (which is derived from the manpage), or fcrackzip.html

There is a web page with more information at http://lehmann.home.ml.org/fcrackzip.html or http://www.goof.com/pcg/marc/fcrackzip.html

A sample password-protected .zip file is included as "noradi.zip". It's password has 6 lower case characters, and fcrackzip will find it (and a number of false positives) with

fcrackzip -b -c a -p aaaaaa ./noradi.zip

which will take between one and thirty minutes on typical machines.

To find out which of these passwords is the right one either try them out or use the --use-unzip option.

Marc

Related Skills

View on GitHub
GitHub Stars467
CategoryDevelopment
Updated14d ago
Forks79

Languages

C

Security Score

95/100

Audited on Mar 14, 2026

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