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
