Crypto入门 (五）混合编码

前言：

　　这次得题目从本质上说没有什么难点，是多次利用base64和16进制编码，层层解开就好，通过这题得代码编写能很好得锻炼python代码能力，一起加油，尝试着自己写写看看把。

混合编码：

题目：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

分析: 下载题目后发现，结尾出有等号而且两个，不由的想到Base64，这个编码方式我们前面已经提到过了就不多说了

先写个代码，解解码，python代码如下：

import base64

with open(r'F:\桌面\tmp\1.txt','r') as f:
    data = f.read()

def base64decode(data):
    data = bytes(data, encoding="utf8")
    data = base64.b64decode(data)
    return data

print(base64decode(data))

运行结果如下：

1 b'LzExOS8xMDEvMTA4Lzk5LzExMS8xMDkvMTAxLzExNi8xMTEvOTcvMTE2LzExNi85Ny85OS8xMDcvOTcvMTEwLzEwMC8xMDAvMTAxLzEwMi8xMDEvMTEwLzk5LzEwMS8xMTkvMTExLzExNC8xMDgvMTAw'

很明显发现都是$#开头，网上百度一番 https://www.jianshu.com/p/6dcefb2a59b2 ，这篇文章说了  以「&#」开头的后接十进制数字，所以先变成16进制然后解码，思路有了，开始写代码

 1 import base64
 2
 3 with open(r'F:\桌面\tmp\1.txt','r') as f:
 4     data = f.read()
 5
 6 def base64decode(data):
 7     data = bytes(data, encoding="utf8")
 8     data = base64.b64decode(data)
 9     return data
10
11 data= base64decode(data)
12 data =   bytes.decode(data)
13
14
15
16 def base16decode(data):
17     m = ''
18     pattern = re.compile('[0-9]{2,3}')
19     result = pattern.findall(data)
20
21     for i in result:
22         m += chr(int(i))
23     return m
24
25 data = base16decode(data)
26 print(data)

然后我们来看下结果：

1 LzExOS8xMDEvMTA4Lzk5LzExMS8xMDkvMTAxLzExNi8xMTEvOTcvMTE2LzExNi85Ny85OS8xMDcvOTcvMTEwLzEwMC8xMDAvMTAxLzEwMi8xMDEvMTEwLzk5LzEwMS8xMTkvMTExLzExNC8xMDgvMTAw

嗯哼，有点像Base64，先测试下，长度能不能被8整除，如果可以那很大概率是Base64啦，给代码

1 str = 'LzExOS8xMDEvMTA4Lzk5LzExMS8xMDkvMTAxLzExNi8xMTEvOTcvMTE2LzExNi85Ny85OS8xMDcvOTcvMTEwLzEwMC8xMDAvMTAxLzEwMi8xMDEvMTEwLzk5LzEwMS8xMTkvMTExLzExNC8xMDgvMTAw'
2
3 if len(str) % 8 == 0:
4     print(len(str))
5     print('可以被8整除')

结果是可以被8整除，故我们再用base64解码一下试试，代码后面一起给出，先贴出解码后的结果：

b'/119/101/108/99/111/109/101/116/111/97/116/116/97/99/107/97/110/100/100/101/102/101/110/99/101/119/111/114/108/100'

感觉被套娃了，没办法，再base16解码，给出全部的代码：

 1 import base64
 2
 3 with open(r'F:\桌面\tmp\1.txt','r') as f:
 4     data = f.read()
 5
 6 print(data)
 7 def base64decode(data):
 8     data = bytes(data, encoding="utf8")
 9     data = base64.b64decode(data)
10     return data
11
12 data= base64decode(data)
13 data =   bytes.decode(data)
14 print(data)
15
16
17 def base16decode(data):
18     m = ''
19     pattern = re.compile('[0-9]{2,3}')
20     result = pattern.findall(data)
21
22     for i in result:
23         m += chr(int(i))
24     return m
25
26 data = base16decode(data)
27 print(data)
28
29 data = base64decode(data)
30 print(data)
31
32 def base16decode1(data):
33     m = ''
34     data =   bytes.decode(data)
35     pattern = re.compile('[0-9]{3}')
36     result = pattern.findall(data)
37
38     for i in result:
39         m += chr(int(i))
40     return m
41 print(base16decode1(data))

给出结果：

1 welometottknddefeneworld

哈哈，还是被解出来了，根据解出的步骤反推加密步骤为，先转成16进制，然后再base64编码 ，再转成16 进制，再base64编码，套娃！！！！

除了这种常规思路，我们也可以参考之前那个链接后面提到的方法直接用浏览器解析

参考链接：

https://www.jianshu.com/p/6dcefb2a59b2

https://www.cnblogs.com/yuanchu/p/13467058.html