南邮CTF-RE-Py交易

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pyc的反编译工具是uncompyle6

root@kali:~/Desktop# uncompyle6 Py.pyc > 1.py

得到反编译后的py文件

# uncompyle6 version 3.2.3
# Python bytecode 2.7 (62211)
# Decompiled from: Python 2.7.13 (default, Jan 19 2017, 14:48:08) 
# [GCC 6.3.0 20170118]
# Embedded file name: 1.py
# Compiled at: 2017-06-02 22:20:43
import base64

def encode(message):
    s = ''
    for i in message:
        x = ord(i) ^ 32
        x = x + 16
        s += chr(x)

    return base64.b64encode(s)


correct = 'XlNkVmtUI1MgXWBZXCFeKY+AaXNt'
flag = ''
print 'Input flag:'
flag = raw_input()
if encode(flag) == correct:
    print 'correct'
else:
    print 'wrong'
# okay decompiling Py.pyc

简单的加密，写个解密函数即可

def decode(message):
    s = ''
    message = base64.b64decode(message)
    for i in message:
        x = ord(i) - 16
        x = x ^ 32
        s += chr(x)
    return s    

print decode('XlNkVmtUI1MgXWBZXCFeKY+AaXNt')
# nctf{d3c0mpil1n9_PyC}