First of all: sorry asking this question. I have seen that this question has been asked before, but I didn't fully understand the answers and couldn't find find anymore information through googling so I thought I would ask.

So onto my problem. So I have a piece of ciphertext that is 1325 characters long with no key information available. Looking at the frequency analysis I was able to determine that the ciphertext was encrypted using a columnar transposition. Now I do not know the key or its length but I plugged the ciphertext into http://www.cryptoprograms.com. I was asked for the minimum and maximum period, and through random guessing I managed to guess the correct period and solve the encryption but I would like to understand how to do it properly.

So the first question is: what is the period of a cipher? I could not seem to get any information about what this means online.

So my second question, from a previous post, I saw that a way to solve a columnar transposition is to calculate the factors of the alphabet length to determine how many columns are (in this case 1,25,53,265,1325). According to wikipedia, rearranging the columns reforms the words. Is there an efficient way of ordering the columns, or is it just a matter of switching them around until a set of words appears that makes sense?

Final question, this question is insanely generalized but, what is the step by step procedure of solving a columnar transposition? (OK this question is insanely weak but I am starting to peter out, the battery on my laptop is dying so I will leave it up until I have a rest and hopefully I can come up with a better question).

Thank you in advance for any help/input you can give.


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