Don't you hate when you run into a locked down pdf on the web? I search google all the time for title filetype:pdf and some are locked, this is the solution! 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).
* Supports the standard security handler (revision 2 and 3) 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)