Source Code for Module bootlegger.cryptfile

 1  from Crypto.Cipher import AES 
 2  import struct 
 3   
 4  CHUNK_SIZE = 32768 
 5   
 6 -def encrypt_chunk(f, aes): 
 7      chunk = f.read(CHUNK_SIZE) 
 8      realn = len(chunk) 
 9   
10      if realn == 0: 
11          return '' 
12   
13      if realn % 16 != 0: 
14          padding = 16 - (realn % 16) 
15          chunk += ' ' * padding 
16   
17      head = struct.pack('!H', realn) 
18       
19      return head + aes.encrypt(chunk) 
20   
21 -def decrypt_chunk(f, aes): 
22      headn = struct.calcsize('!H') 
23      head = f.read(headn) 
24   
25      if len(head) == 0: 
26          return '' 
27   
28      realn, = struct.unpack('!H', head) 
29   
30      if realn % 16 != 0: 
31          n = realn + (16 - (realn % 16)) 
32      else: 
33          n = realn 
34   
35      chunk = f.read(n) 
36      plain = aes.decrypt(chunk) 
37   
38      return plain[:realn] 
39   
40 -def transform_file(infname, outfname, key, chunk_func): 
41      inf = open(infname, 'rb') 
42      outf = open(outfname, 'wb') 
43       
44      aes = AES.new(key) 
45      chunk = chunk_func(inf, aes) 
46   
47      while chunk: 
48          outf.write(chunk) 
49          chunk = chunk_func(inf, aes) 
50   
51      inf.close() 
52      outf.close() 
53   
54 -def encrypt_file(infname, outfname, key): 
55      transform_file(infname, outfname, key, encrypt_chunk) 
56   
57 -def decrypt_file(infname, outfname, key): 
58      transform_file(infname, outfname, key, decrypt_chunk) 
59