Nzix
6 years ago
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# Netease Cloud Music Copyright Protection File Dump (Python version) |
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## 简介 |
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早就在算计网易云ncm文件,不过一直没什么机会,前些天突然看到已经有大佬 [anonymous5l/ncmdump ](https://github.com/anonymous5l/ncmdump)实现了,因为好奇加密算法就用Python移植了下,啊大佬不愧是大佬,感激!测试发现转换出来的媒体文件都已包含媒体信息,故未再实现原repo中的写tag操作。还有Python实现比C++慢不少。仅供学习交流,请勿传播扩散。用Python处理字节真让人头大emmm |
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## 依赖 |
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``` |
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pip(3) install pycrypto |
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``` |
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## 使用 |
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``` |
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python(3) ncmdump.py [files ...] |
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``` |
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# -*- coding: utf-8 -*- |
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""" |
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Created on Sun Jul 15 01:05:58 2018 |
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@author: Nzix |
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""" |
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import binascii |
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import struct |
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import base64 |
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import json |
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import os |
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from Crypto.Cipher import AES |
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def dump(file_path): |
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core_key = binascii.a2b_hex("687A4852416D736F356B496E62617857") |
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meta_key = binascii.a2b_hex("2331346C6A6B5F215C5D2630553C2728") |
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unpad = lambda s : s[0:-(s[-1] if type(s[-1]) == int else ord(s[-1]))] |
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f = open(file_path,'rb') |
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# magic header |
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header = f.read(8) |
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assert binascii.b2a_hex(header) == b'4354454e4644414d' |
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# key data |
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f.seek(2, 1) |
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key_length = f.read(4) |
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key_length = struct.unpack('<I', bytes(key_length))[0] |
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key_data = f.read(key_length) |
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key_data_array = bytearray(key_data) |
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i = 0 |
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while i < len(key_data_array): |
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key_data_array[i] ^= 0x64 |
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i += 1 |
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key_data = bytes(key_data_array) |
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cryptor = AES.new(core_key, AES.MODE_ECB) |
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key_data = unpad(cryptor.decrypt(key_data))[17:] |
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key_length = len(key_data) |
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# key box |
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key_data = bytearray(key_data) |
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key_box = bytearray(range(256)) |
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c = 0 |
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last_byte = 0 |
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key_offset = 0 |
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for i in range(256): |
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swap = key_box[i] |
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c = (swap + last_byte + key_data[key_offset]) & 0xff |
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key_offset += 1 |
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if key_offset >= key_length: |
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key_offset = 0 |
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key_box[i] = key_box[c] |
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key_box[c] = swap |
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last_byte = c |
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# meta data |
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meta_length = f.read(4) |
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meta_length = struct.unpack('<I', bytes(meta_length))[0] |
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meta_data = f.read(meta_length) |
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meta_data_array = bytearray(meta_data) |
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i = 0 |
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while i < len(meta_data_array): |
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meta_data_array[i] ^= 0x63 |
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i += 1 |
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meta_data = bytes(meta_data_array) |
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meta_data = base64.b64decode(meta_data[22:]) |
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cryptor = AES.new(meta_key, AES.MODE_ECB) |
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meta_data = unpad(cryptor.decrypt(meta_data)).decode('utf-8')[6:] |
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meta_data = json.loads(meta_data) |
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# crc32 |
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crc32 = f.read(4) |
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crc32 = struct.unpack('<I', bytes(crc32))[0] |
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# album cover |
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f.seek(5, 1) |
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image_size = f.read(4) |
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image_size = struct.unpack('<I', bytes(image_size))[0] |
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image_data = f.read(image_size) |
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# media data |
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file_name = meta_data['musicName'] + '.' + meta_data['format'] |
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m = open(os.path.join(os.path.split(file_path)[0],file_name),'wb') |
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chunk = bytearray() |
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while True: |
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chunk = bytearray(f.read(0x8000)) |
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chunk_length = len(chunk) |
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if not chunk: |
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break |
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for i in range(chunk_length): |
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j = (i + 1) & 0xff; |
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chunk[i] ^= key_box[(key_box[j] + key_box[(key_box[j] + j) & 0xff]) & 0xff] |
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m.write(chunk) |
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m.close() |
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f.close() |
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if __name__ == '__main__': |
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import sys |
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if len(sys.argv) > 1: |
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for file_path in sys.argv[1:]: |
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try: |
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dump(file_path) |
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except: |
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pass |
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else: |
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print('please input file path!') |
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