Very simple substitution encryption cracker using quadgram's to analyze the text.
It seems to work as long as the text is long.
It takes to command line argument: First argument is a text file to "learn" a language from. Project Gutenberg is a good start to find these text files.
Second argument is the filename of text file containing the encrypted text.
During cracking it will show you a status with best key and first 200 characters of the best solution until then.
The program runs until ctrl-c is pressed.