Nahamcon 2024

Base3200

Solved by: Legend

• We are given theflag.xz file which is used for high compression.

• The compressed file contains a file named theflag which contains a very long encoded string.

• At first I thought it was just base64 with very long string but it was not getting decoded.

• I googled and found past CTF on this.
• http://dann.com.br/3dsctf-2016-misc100-base3200/ → Script didn’t work

• https://ctf-writeup.blogspot.com/2016/12/3ds-ctf.html → Script worked

• Basically what is happening here is we are dividing 3200 with 64 because the data is encoded 50 times.

import base64 

file = open('theflag.txt', 'r')
file_data = file.read()

for i in range (50):
 file_data = base64.b64decode(file_data)

flag = file_data.decode('utf-8')
print(f'Flag: {flag}')

Flag: flag{340ff1bee05244546c91dea53fba7642}