[FlareOn3]Challenge1.zip

ida 直接找到关键函数

Func 函数

发现是 base64 的代码。看看 对应的base表是多少

新的 base 表为 “ZYXABCDEFGHIJKLMNOPQRSTUVWzyxabcdefghijklmnopqrstuvw0123456789+/”

利用 换表的 base64 解密 得到对应的答案

# -*- coding: UTF-8 -*-
base = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
diy_base = "ZYXABCDEFGHIJKLMNOPQRSTUVWzyxabcdefghijklmnopqrstuvw0123456789+/"
cipher  = "x2dtJEOmyjacxDemx2eczT5cVS9fVUGvWTuZWjuexjRqy24rV29q"
new_cipher = ""

for i in range(len(cipher)):
    new_cipher += base[diy_base.find(cipher[i])]
print "new_cipher: " + new_cipher

flag = new_cipher.decode("base64")
print flag

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