I’ve used a lot of different software in a tireless effort to brute force a password out of a single PDF. So far, Elcomsoft Distributed Password Recovery certainly helps to speed up the process dramatically, but is it enough to reasonably crack a standard 8 character password in a reasonable amount of time?
As it turns out, that depends on what type of file you are trying to recover the password on. For example, PDF files are unable to take advantage of GPU acceleration (such as NVIDIA’s CUDA), while WPA/WPA2 (.cap/.wph files) are supported. Either way, be prepared to wait a long time, or drop a lot of money on a lot of CPU/GPU power because once you get up to just a measily 8 characters, it can take years.