PDFCrack is a GNU/Linux (other POSIX-compatible systems should work too) tool for recovering passwords and content from PDF-files. It is small, command line driven without external dependencies. The application is Open Source (GPL).
Features

* Supports the standard security handler (revision 2, 3 and 4) on all known PDF-versions
* Supports cracking both owner and userpasswords
* Both wordlists and bruteforcing the password is supported
* Simple permutations (currently only trying first character as Upper Case)
* Save/Load a running job
* Simple benchmarking
* Optimised search for owner-password when user-password is known