Cyber Apocalypse 2024
Dynastic
Solved by : Starry-lord
This challenge comes with an output.txt and a python source as you can see below:
from secret import FLAG
from random import randint
def to_identity_map(a):
return ord(a) - 0x41
def from_identity_map(a):
return chr(a % 26 + 0x41)
def encrypt(m):
c = ''
for i in range(len(m)):
ch = m[i]
if not ch.isalpha():
ech = ch
else:
chi = to_identity_map(ch)
ech = from_identity_map(chi + i)
c += ech
return c
with open('output.txt', 'w') as f:
f.write('Make sure you wrap the decrypted text with the HTB flag format :-]\n')
f.write(encrypt(FLAG))
We needed to write a decryption mechanism for this, taking the output file as input. Here’s my solution:
HTB{DID_YOU_KNOW_ABOUT_THE_TRITHEMIUS_CIPHER?!_IT_IS_SIMILAR_TO_CAESAR_CIPHER}