import itertools

def xor_decrypt(hex_encoded, key):
    data = bytes.fromhex(hex_encoded)
    decrypted = ''
    for i in range(len(data)):
        decrypted += chr(data[i] ^ ord(key[i % len(key)]))
    return decrypted

def recover_xor_key(hex_encoded, known_start="THM{", known_end="}"):
    data = bytes.fromhex(hex_encoded)

    # Step 1: Recover partial key from known prefix
    partial_key = [chr(data[i] ^ ord(known_start[i])) for i in range(len(known_start))]

    # Step 2: Brute-force remaining characters of 5-character key
    charset = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
    key_length = 5
    unknown_length = key_length - len(partial_key)

    for combo in itertools.product(charset, repeat=unknown_length):
        key = ''.join(partial_key + list(combo))
        decrypted = xor_decrypt(hex_encoded, key)
        if decrypted.startswith(known_start) and decrypted.endswith(known_end):
            return key, decrypted

    return None, None

if __name__ == "__main__":
    hex_encoded = "272f0549124206245c16361f3c731607532b590132093a01031f2b315a370113310217011f07401f"
    key, message = recover_xor_key(hex_encoded)

    if key:
        print("✅ Found key:", key)
        print("🔓 Decrypted message:", message)
    else:
        print("❌ Key not found.")