9. Favourite byte

Challenge Description:

For the next few challenges, you'll use what you've just learned to solve some more XOR puzzles.

I've hidden some data using XOR with a single byte, but that byte is a secret. Don't forget to decode from hex first.

73626960647f6b206821204f21254f7d694f7624662065622127234f726927756d

My Solution:

Since the XOR key is one byte, we can brute force it by trying all the bytes, and when we get the flag we will know the correct XOR key:

from pwn import *

EncryptData = bytes.fromhex("73626960647f6b206821204f21254f7d694f7624662065622127234f726927756d")

for i in range(255):
    XORing = xor(EncryptData, i).decode(errors="ignore")
    if XORing.startswith("crypto"):
        print("Here is your flag:")
        print(XORing, hex(i))

The Flag:

crypto{0x10_15_my_**************}

XOR key was 0x10.