There are software's tools to crack PDF passwords and unlock PDF restrictions, now there is a dedicated hardware and software combination to tackle the issue. Named "BeagleBone" the specialized "PDF password cracker" is a dedicated solution consisting of embedded Linux and a 700 MHz ARM processor, you simply need to insert a thumb-drive having the encoded/locked/password-protected PDF files and click a button to start the cracking process. In it's current form the "BeagleBone" uses a single ARM processor to brute-force crack the password by trying 6000 four-character passwords per second, but the interesting part is - multiple parallel ARM processors can be used to achieve faster decryption.