題目連結#
https://learn.cylabacademy.org/library/241
題目解法#
下載腳本並執行後可以發現在第 22 行的地方報錯。
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| $ python fixme2.py
File "/home/kali/workspace/fixme2.py", line 22
if flag = "":
^^^^^^^^^
SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?
|
使用 nano 或其他習慣的文字編輯器編輯檔案，將第 22 行的 = 改成 ==。
nano fixme2.py
要退出 nano 要按下 Ctrl + X，接著按下 Y，再按下 Enter 即可退出。
退出後再次執行 python 腳本即可得到 flag。
$ python fixme2.py
That is correct! Here's your flag: picoCTF{3qu--------------------------efc}
題目原始碼#
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|
import random
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 = chr(0x15) + chr(0x07) + chr(0x08) + chr(0x06) + chr(0x27) + chr(0x21) + chr(0x23) + chr(0x15) + chr(0x58) + chr(0x18) + chr(0x11) + chr(0x41) + chr(0x09) + chr(0x5f) + chr(0x1f) + chr(0x10) + chr(0x3b) + chr(0x1b) + chr(0x55) + chr(0x1a) + chr(0x34) + chr(0x5d) + chr(0x51) + chr(0x40) + chr(0x54) + chr(0x09) + chr(0x05) + chr(0x04) + chr(0x57) + chr(0x1b) + chr(0x11) + chr(0x31) + chr(0x0d) + chr(0x5f) + chr(0x05) + chr(0x40) + chr(0x04) + chr(0x0b) + chr(0x0d) + chr(0x0a) + chr(0x19)
flag = str_xor(flag_enc, 'enkidu')
# Check that flag is not empty
if flag = "":
print('String XOR encountered a problem, quitting.')
else:
print('That is correct! Here\'s your flag: ' + flag)
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