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Imposters

Description

Some things may pretend to be something they are not.

re.py

Figure out what this atrocity of a code does to get the flag

Points: 300


Hints to the Solution

Several hints here

The first thing that comes to your mind ( hopefully ) is why in hell are there 3 definitions of converts . Look closely though! ( Hint: Even Github highlights them in different colours! )

The same mischief that is up wih converts is applied to the variables flags and sr

Don't overlook the self-XOR! Also remember that A ⊕ B ⊕ A = B

Oh! And those lists of numbers? Don't they look awfully similar to ASCII Codes?

Steps to the Solution
  • Though all converts functions look the same to humans, they are different to the computer ( as one uses plain english letters, one uses an exotic (unicode) s and one uses an exotic e) . A good text editor can help you easily differentiate them.
  • The same is the case with the variables flags and sr
  • All 3 definitions of converts are executed (figure out in what order) with the output of one passed as input to the other. Though only one of these is actually doing something that persists.
  • Which coverts is actually doing something? Use the understanding of flags and sr to figure this one out.
  • The input inp is broken down into a list of digits.
  • The self-xor and the above mentioned property of XOR should be a starting point to generate the values of inp list
  • Once you calculate the correct value of inp, it will generate the flag for you