酷狗缓存文件kgtemp解密

本文参考于https://www.cnblogs.com/KMBlog/p/6877752.html
大神破解了酷狗缓存文件kgtemp的加密解密方式，遂用python实现之。
kugou.py

# coding:utf-8
import os 
import sys

key = [0xAC, 0xEC, 0xDF, 0x57]

def crack_file(argv):
    filename = argv[0]
    new_name = argv[1]

    file = open(filename, "rb")
    file.seek(1024, os.SEEK_SET)  # 偏移量1024
    changed_file = open(new_name, 'wb+')  # 以二进制追加写的方式打开

    try:
        b = file.read(4)  #  一次读4个字节  type(b)  --> 'bytes'
        while(b):   
            for num,i in enumerate(b):
                h = i >> 4  # type(i) --> int
                l = i & 0xf
                kh = key[num] >> 4
                kl = key[num] & 0xf
                y = l ^ kl
                y = (h ^ kh ^ y) << 4 | y

                temp = bytes([y])  #  将int转为bytes
                changed_file.write(temp)
            b = file.read(4)
    except Exception as e:
        print(e)
    else:
        print("成功")
    finally:
        file.close()
        changed_file.close()

if __name__ == "__main__":
    crack_file(sys.argv[1:])

运行方式python3中运行 python kugou.py 要转换的文件名 新名字

检查新文件的MD5值，看是否和原文件的名字一样

import hashlib

filename = "xxxx"
with open(filename, 'rb') as f:
    md5obj = hashlib.md5()
    md5obj.update(f.read())
    hash = md5obj.hexdigest()
    print(hash)

注：

1. 关于int转bytes问题见https://stackoverflow.com/questions/21017698/converting-int-to-bytes-in-python-3
2. python二进制读写见http://blog.youkuaiyun.com/lesky/article/details/5727473
   如

import struct
temp = struct.pack("B", 12)  # 将int转为bytes