Phase Stream 1

The challenge was a repeating 5-byte string is the key to this XOR'ed string. To solve, I brute-forced 5-byte strings until I found a match to the flag's prefix CHTB{.

Here is my code:

from string import ascii_lowercase
from itertools import product
s1 = '2e313f2702184c5a0b1e321205550e03261b094d5c171f56011904'
# only generate 5 bytes
for x in range(5, 6):
for combo in product(ascii_lowercase, repeat=x):
# xor the two strings as bytes
cur = bytes([a ^ b for a, b in zip(bytes(''.join(combo), 'utf-8'), bytes.fromhex(s1))])
# if found output the key and the flag
if (cur == b'CHTB{'):
key = ''.join(combo)
print("Key found!", key)
print("Flag:", bytes([a ^ b for a, b in zip(bytes(''.join(combo)*6, 'utf-8'), bytes.fromhex(s1))]).decode('utf-8'))

Overall not to bad.