Reply To: !
@_hacker_
I had a quick look at your code and believe the most likely reason it gets stuck is the mutate key function. Swapping letters is not always enough for playfair, my tool has over 10 different operations it can perform on the key. Try come up with a few mutations you can do to the grid (Madness’ book mentions a few but not all).
You might also want to experiment with temperature and probabilities to find which work best (maybe even a hill climbing algorithm to optimise your hill climbing algorithm).
Sorry I can’t provide much more information, Harry is (rightfully) enforcing the “all my own work” rule and this post needs to get through moderation.
@Gen_ruikt
Have a look at unit 70 in Madness’ book, it does a great job at explaining it, there are also other materials online.
The short answer is that letters on the grid are treated as corners of a rectangle and the other 2 corners are the encrypted pair (the text is encrypted in groups of 2 at a time).