Beginner picoMini 2022 writeup PW Crack 5

PW Crack 5 (General Skills)

Can you crack the password to get the flag? Download the password checker here and you'll need the encrypted flag and the hash in the same directory too. Here's a dictionary with all possible passwords based on the password conventions we've seen so far.

添付ファイル
・level5.py
・level5.flag.txt.enc
・level5.hash.bin
・dictionary.txt

dictionary.txtを見てみると、パスワード候補が各行4桁ずつ書かれていた。PW Crack 4とほぼ同じであるが、dictionary.txtを読み込んでパスワード候補を改行区切りでリストに格納する必要がある。
以下、実行コード。

import hashlib

### THIS FUNCTION WILL NOT HELP YOU FIND THE FLAG --LT ########################
def str_xor(secret, key):
    #extend key to secret length
    new_key = key
    i = 0
    while len(new_key) < len(secret):
        new_key = new_key + key[i]
        i = (i + 1) % len(key)        
    return "".join([chr(ord(secret_c) ^ ord(new_key_c)) for (secret_c,new_key_c) in zip(secret,new_key)])
###############################################################################

flag_enc = open('level5.flag.txt.enc', 'rb').read()
correct_pw_hash = open('level5.hash.bin', 'rb').read()
pw_candidate = open('dictionary.txt', 'r').read()


def hash_pw(pw_str):
    pw_bytes = bytearray()
    pw_bytes.extend(pw_str.encode())
    m = hashlib.md5()
    m.update(pw_bytes)
    return m.digest()


def level_5_pw_check(user_pw):
#    user_pw = input("Please enter correct password for flag: ")
#    user_pw_hash = hash_pw(user_pw)
    
#    if( user_pw_hash == correct_pw_hash ):
        print("Welcome back... your flag, user:")
        decryption = str_xor(flag_enc.decode(), user_pw)
        print(decryption)
        return
        print("That password is incorrect")

pw_list = pw_candidate.split()
for i in pw_list:
    if hash_pw(i) == correct_pw_hash:
        a = i


level_5_pw_check(a)

picoCTF{h45h_sl1ng1ng_40f26f81}