Category: Misc - Points: 50

Description:

ex1
Cipher:PXFR}QIVTMSZCNDKUWAGJB{LHYEO
Plain: ABCDEFGHIJKLMNOPQRSTUVWXYZ{}

ex2
Cipher:EV}ZZD{DWZRA}FFDNFGQO
Plain: {HELLOWORLDSECCONCTF}

quiz
Cipher:A}FFDNEVPFSGV}KZPN}GO
Plain: ?????????????????????

This is the first challenge and it is just a sanity check. From the description it is clear that we are given a substitution cipher and we have to decode the last message.

Substitution Cipher

We wrote the following python script, using maketrans and translate.

#!/usr/bin/env python

from string import maketrans, translate

table = maketrans('PXFR}QIVTMSZCNDKUWAGJB{LHYEO', 'ABCDEFGHIJKLMNOPQRSTUVWXYZ{}')
cipher = 'A}FFDNEVPFSGV}KZPN}GO'
print translate(cipher, table)

We then execute the script:

$ ./solve.py
SECCON{HACKTHEPLANET}

So the flag is: SECCON{HACKTHEPLANET}