/gdata/tlslite/utils/OpenSSL_TripleDES.py
http://radioappz.googlecode.com/ · Python · 44 lines · 30 code · 9 blank · 5 comment · 1 complexity · 0ad5778e742f9a39ff29ff4e72624da1 MD5 · raw file
- """OpenSSL/M2Crypto 3DES implementation."""
- from cryptomath import *
- from TripleDES import *
- if m2cryptoLoaded:
- def new(key, mode, IV):
- return OpenSSL_TripleDES(key, mode, IV)
- class OpenSSL_TripleDES(TripleDES):
- def __init__(self, key, mode, IV):
- TripleDES.__init__(self, key, mode, IV, "openssl")
- self.key = key
- self.IV = IV
- def _createContext(self, encrypt):
- context = m2.cipher_ctx_new()
- cipherType = m2.des_ede3_cbc()
- m2.cipher_init(context, cipherType, self.key, self.IV, encrypt)
- return context
- def encrypt(self, plaintext):
- TripleDES.encrypt(self, plaintext)
- context = self._createContext(1)
- ciphertext = m2.cipher_update(context, plaintext)
- m2.cipher_ctx_free(context)
- self.IV = ciphertext[-self.block_size:]
- return ciphertext
- def decrypt(self, ciphertext):
- TripleDES.decrypt(self, ciphertext)
- context = self._createContext(0)
- #I think M2Crypto has a bug - it fails to decrypt and return the last block passed in.
- #To work around this, we append sixteen zeros to the string, below:
- plaintext = m2.cipher_update(context, ciphertext+('\0'*16))
- #If this bug is ever fixed, then plaintext will end up having a garbage
- #plaintext block on the end. That's okay - the below code will ignore it.
- plaintext = plaintext[:len(ciphertext)]
- m2.cipher_ctx_free(context)
- self.IV = ciphertext[-self.block_size:]
- return plaintext