Over the Wire - Bandit 12

Bandit 12


Objective
The password for the next level is stored in the file data.txt, where all lowercase (a-z) and uppercase (A-Z) letters have been rotated by 13 positions

Solution

This level has the password in data.txt but it has been encrypted with a Cesar cipher with a 13 position shift.  This is also called ROT13 if you wanna google around for it.

we can read the file and pipe it into the translate command 'tr' the basic syntax is tr 'original  dataset' 'translated dataset'
so to decode the syntax a bit more

The Original data set is A-Z in uppercase and a-z in lower case
but we want it to translate where the alphabet is shifted over 13 chacters so a becomes n, b becomes o..... and so on

so the translated data set is broken out to

N-ZA-M  for upper case so use the alphabet in this order where the first letter of the alphabet is N and the last letter is M
and then the same thing for lowercase characters

bandit11@bandit:~$ cat  data.txt | tr 'A-Za-z' 'N-ZA-Mn-za-m'The password is 5Te8Y4drgCRfCx8ugdwuEX8KFC6k2EUu

Now in Python

import base64import codecs
with open("data.txt") as f: contents = f.read() decoded = codecs.decode(contents, 'rot_13')
 print(decoded)
The password is 5Te8Y4drgCRfCx8ugdwuEX8KFC6k2EUu