Package tlslite :: Package utils :: Module openssl_tripledes
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Source Code for Module tlslite.utils.openssl_tripledes

 1  # Author: Trevor Perrin 
 2  # See the LICENSE file for legal information regarding use of this file. 
 3   
 4  """OpenSSL/M2Crypto 3DES implementation.""" 
 5   
 6  from .cryptomath import * 
 7  from .tripledes import * 
 8   
 9  if m2cryptoLoaded: 
10   
11 - def new(key, mode, IV):
12 return OpenSSL_TripleDES(key, mode, IV)
13
14 - class OpenSSL_TripleDES(TripleDES):
15
16 - def __init__(self, key, mode, IV):
17 TripleDES.__init__(self, key, mode, IV, "openssl") 18 self.key = key 19 self.IV = IV
20
21 - def _createContext(self, encrypt):
22 context = m2.cipher_ctx_new() 23 cipherType = m2.des_ede3_cbc() 24 m2.cipher_init(context, cipherType, self.key, self.IV, encrypt) 25 return context
26
27 - def encrypt(self, plaintext):
28 TripleDES.encrypt(self, plaintext) 29 context = self._createContext(1) 30 ciphertext = m2.cipher_update(context, plaintext) 31 m2.cipher_ctx_free(context) 32 self.IV = ciphertext[-self.block_size:] 33 return bytearray(ciphertext)
34
35 - def decrypt(self, ciphertext):
36 TripleDES.decrypt(self, ciphertext) 37 context = self._createContext(0) 38 #I think M2Crypto has a bug - it fails to decrypt and return the last block passed in. 39 #To work around this, we append sixteen zeros to the string, below: 40 plaintext = m2.cipher_update(context, ciphertext+('\0'*16)) 41 42 #If this bug is ever fixed, then plaintext will end up having a garbage 43 #plaintext block on the end. That's okay - the below code will ignore it. 44 plaintext = plaintext[:len(ciphertext)] 45 m2.cipher_ctx_free(context) 46 self.IV = ciphertext[-self.block_size:] 47 return bytearray(plaintext)
48