Source Code for Module Anomos.Crypto._AESKey

 1  import cStringIO 
 2   
 3  from M2Crypto import EVP 
 4  from Anomos.Crypto import global_cryptodir, global_randfile 
 5  import Anomos.Crypto 
 6   
 7  from Anomos import LOG as log 
 8 -class AESKey: 
 9 -    def __init__(self, key=None, iv=None, algorithm='aes_256_cfb'): 
10          """ 
11          @param algorithm: encryption algorithm to use 
12          @param key: 32 byte string to use as key 
13          @param iv: 32 byte initalization vector to use 
14          """ 
15          if None in (global_cryptodir, global_randfile): 
16              raise CryptoError('RNG not initialized, call initCrypto first') 
17          self.randfile=global_randfile 
18          self.algorithm = algorithm 
19   
20          if key: 
21              self.key = key 
22          else: 
23              self.key = Anomos.Crypto.get_rand() 
24          if iv: 
25              self.iv = iv 
26          else: 
27              self.iv = Anomos.Crypto.get_rand() 
28           
29          ##keep the ciphers warm, iv only needs to be used once 
30          self.encCipher = EVP.Cipher(self.algorithm, self.key, self.iv, 1) 
31          self.decCipher = EVP.Cipher(self.algorithm, self.key, self.iv, 0) 
32   
33      ##this is where the actual ciphering is done 
34 -    def cipher_filter(self, cipher, inf, outf): 
35          buf=inf.read() 
36          outf.write(cipher.update(buf)) 
37          outf.write(cipher.final()) 
38          return outf.getvalue() 
39   
40 -    def encrypt(self, text): 
41          """ 
42          @param text: Plaintext to encrypt 
43          @type text: string 
44          """ 
45          sbuf=cStringIO.StringIO(text) 
46          obuf=cStringIO.StringIO() 
47          encoder = self.encCipher 
48          encrypted = self.cipher_filter(encoder, sbuf, obuf) 
49          sbuf.close() 
50          obuf.close() 
51          return encrypted 
52   
53 -    def decrypt(self, text): 
54          """ 
55          @param text: Ciphertext to decrypt 
56          @type text: string 
57          """ 
58          obuf = cStringIO.StringIO(text) 
59          sbuf = cStringIO.StringIO() 
60          decoder = self.decCipher 
61          decrypted = self.cipher_filter(decoder, obuf, sbuf) 
62          sbuf.close() 
63          obuf.close() 
64          return decrypted 
65