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.