I'm reading from Cornell , I know for a single permutation, I can find the ciphertext length (100), divide in some key lengths (10x10, 5x20), then try all permutation (10x9x8... 5x4x3x2x1). then find anything legible.
Is there any case the above method will not work, and is there any better method to crack this permutation cipher?
Also, what if I use two-permutation patterns, for example; for the 100 plaintext length:
- I divide it into 10 characters per column.
- Then for the first 4 characters - I use one permutation.
- For the next 6 characters, I use another permutation.
Am I right that this makes no difference on the cracking step? i.e. I tried 10x10, then I tried all permutations 10! I will find anything legible.