Solution for challenge Weak Rivest 4 at the Insomni'hack 2022 CTF

r4c.py

import time

pt1 = "495F646F5F6E6F745F6C696B655F706F6E696573"
ct1 = "D058DECB037A10916E9D8B0E5345BB381AE8D8EE"
ct2 = "D049E9DF182420AB5EC6BD101229940517B59CE0"

flag = ""

for i in range(0, len(ct1) - 1, 2):
    ct1_pair = int("0x" + ct1[i:i+2], 16) # Get two characters from ct1
    ct2_pair = int("0x" + ct2[i:i+2], 16) # Get two characters from ct2
    result = ct1_pair ^ ct2_pair
    for k in range (0x0, 0x7f): # Loop over all characters in the ASCII table
        if (int("0x" + pt1[i:i+2], 16) ^ k) == result: # Check if the XORed number is the same as the result
            flag += chr(k)
            print(flag, end="\r")
            time.sleep(0.5) # That is just to look cool 😎
            break