I'm taking my first cryptography course and having trouble deciphering some Vigenere encrypted text.

The Ciphertext

I was able to crack the first one:

First Question

I'm having difficulty with the other two. I think the solution to #2 and #3 lies in the wording of the question. It says that the "message format" is the same as the first one, but what does that actually mean? Are the numbers arranged in the same way (i.e. first number is 3 chars long, second is four chars, third is four chars, etc)? I've been trying out a bunch of approaches but i'm not getting anywhere. Please help!


Same format means they are numbers. So you have to try the combinations to match. In other words, you are performing an attack on limited message space. Produce combinations of numbers.


Before this applying Kasiski test to determine the key length may be helpfull to reduce the string lengths.

Good luck!


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