In hindsight, rolling my own crypto was a rather stupendous stroke of stupidity. I'll be switching to a well-known, verified library to fix this.
from Crypto.Util.Padding import pad,unpad
from Crypto.Cipher import AES
import os
with open("flag", 'rb') as f: flag = f.read().strip()
key = os.urandom(16)
while 1:
pt = input('> ').encode()
padded = pad(pt+flag, AES.block_size)
cipher = AES.new(key, AES.MODE_ECB)
print(cipher.encrypt(padded).hex())nc challs.sieberrsec.tech 31311
A first blood prize of one (1) month of Discord Nitro is available for this challenge.
Some amount of "bruteforce" will be necessary -- and hence legal -- for this challenge.
Author: @main
- You should search for ECB related AES crypto CTF problems; this is a rather common newbie challenge