PDFCrack is a GNU/Linux application (or any other POSIX-compatible system) tool for recovering passwords and content from PDF-files. It is small, command line driven without external dependencies. PDFCrack is released under GPL.

Install and pdfcrack on Ubuntu by typing:

cc@zeus:~$ sudo aptitude install pdfcrack

Run a quick cracking power benchmark:

cc@zeus:~/Desktop$ pdfcrack -b
Benchmark:      Average Speed (calls / second):
MD5:                    1728972.6
MD5_50 (fast):          97879.3
MD5_50 (slow):          69167.0

RC4 (40, static):       606555.3
RC4 (40, no check):     598050.0
RC4 (128, no check):    590141.7

Benchmark:      Average Speed (passwords / second):
PDF (40, user):         453510.2
PDF (40, owner):        220250.0
PDF (40, owner, fast):  499995.0

PDF (128, user):        22000.0
PDF (128, owner):       10408.7
PDF (128, owner, fast): 22220.0

Use the pdfcrack to crack an encrypted pdf-file by typing:

cc@zeus:~/Desktop$ pdfcrack test.pdf

Happy pdf-hacking and cracking