Reply To: Extracurricular challenges

[upsidedown]

@Puzzling_Pelican nice, well done. I wonder how long your program took to run?

I think that if I used an autokey keyword length k != 6 you would need to consider n=k/gcd(-6%k, k) rows of the inverse matrix simultaneously, then try n! permutations of those rows, and then solve the resulting sequence as an autokey+vigenere combination. Would certainly be harder, but it’s effectively just multiplying the boring searching part.