1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
| def dump(file_path):
core_key = binascii.a2b_hex("687A4852416D736F356B496E62617857")
meta_key = binascii.a2b_hex("2331346C6A6B5F215C5D2630553C2728")
unpad = lambda s : s[0:-(s[-1] if type(s[-1]) == int else ord(s[-1]))]
f = open(file_path,'rb')
header = f.read(8)
assert binascii.b2a_hex(header) == b'4354454e4644414d'
f.seek(2, 1)
key_length = f.read(4)
key_length = struct.unpack('<I', bytes(key_length))[0]
key_data = f.read(key_length)
key_data_array = bytearray(key_data)
for i in range (0,len(key_data_array)): key_data_array[i] ^= 0x64
key_data = bytes(key_data_array)
cryptor = AES.new(core_key, AES.MODE_ECB)
key_data = unpad(cryptor.decrypt(key_data))[17:]
key_length = len(key_data)
key_data = bytearray(key_data)
key_box = bytearray(range(256))
c = 0
last_byte = 0
key_offset = 0
for i in range(256):
swap = key_box[i]
c = (swap + last_byte + key_data[key_offset]) & 0xff
key_offset += 1
if key_offset >= key_length: key_offset = 0
key_box[i] = key_box[c]
key_box[c] = swap
last_byte = c
meta_length = f.read(4)
meta_length = struct.unpack('<I', bytes(meta_length))[0]
meta_data = f.read(meta_length)
meta_data_array = bytearray(meta_data)
for i in range(0,len(meta_data_array)): meta_data_array[i] ^= 0x63
meta_data = bytes(meta_data_array)
meta_data = base64.b64decode(meta_data[22:])
cryptor = AES.new(meta_key, AES.MODE_ECB)
meta_data = unpad(cryptor.decrypt(meta_data)).decode('utf-8')[6:]
meta_data = json.loads(meta_data)
crc32 = f.read(4)
crc32 = struct.unpack('<I', bytes(crc32))[0]
f.seek(5, 1)
image_size = f.read(4)
image_size = struct.unpack('<I', bytes(image_size))[0]
image_data = f.read(image_size)
file_name = meta_data['musicName'] + '.' + meta_data['format']
m = open(os.path.join(os.path.split(file_path)[0],file_name),'wb')
chunk = bytearray()
while True:
chunk = bytearray(f.read(0x8000))
chunk_length = len(chunk)
if not chunk:
break
for i in range(1,chunk_length+1):
j = i & 0xff;
chunk[i-1] ^= key_box[(key_box[j] + key_box[(key_box[j] + j) & 0xff]) & 0xff]
m.write(chunk)
m.close()
f.close()
|
