Demonstration of an MCMC technique for cracking substitution ciphers.
-Just run the python script from the command line.
-The user is prompted first to supply a large sample of the english language. This will record one-step transition probabilities of letters in the provided text in an array.
-The user is then prompted for a message to be randomly encrypted via a substitution cipher, and then decrypted using the MCMC technique. See bcboniece.wordpress.com for more mathematical detail.
-Added an option to include an "intelligent" starting point for the markov chain using character frequency analysis.