ATHACK CTF

REVERSING CATEGORY

S0Lving_p0lyn0mials_OR_bRuteF0rcing

This writeup is about a reversing challenge i came around last year at the AtHackCtf .

challenge

A python script is provided

This script is basically getting the integer representation of the ascii character of the flag one by one using the ord() function . The code then goes ahead to do some calculations with the integer to yield a very large number. When i run the script i get :

cipher = [317336, 1696274, 425598, 1007448, 1069008, 1340288, 346128, 663858, 392496, 2013024, 2110256]

Remember these are the values you get after the script transforms the characters of this flag part“AtHackCTF{}” . Our task therefore , is to get the other characters of the flag ,from a provided output of the whole flag that we get from the author also.

Solution

You might have figured that this process is kind of irreversible , we can only do it one way. That is trying different characters and matching if the output matches what we have already. We also need to automate this process to save on time. I made a simple script to try just that :

Flag :

AtHackCTF{Which_1s_M0re_Fun_S0Lving_p0lyn0mials_OR_bRuteF0rcing?!}