1  """
 2  Symmetric Encryption
 3  """
 4  #  Copyright (C) 2011 Yann GUIBET <yannguibet@gmail.com>
 5  #  See LICENSE for details.
 6  
 7  from .openssl import OpenSSL
 8  
 9  
10  # pylint: disable=redefined-builtin
11  class Cipher(object):
12      """
13      Main class for encryption
14  
15          import pyelliptic
16          iv = pyelliptic.Cipher.gen_IV('aes-256-cfb')
17          ctx = pyelliptic.Cipher("secretkey", iv, 1, ciphername='aes-256-cfb')
18          ciphertext = ctx.update('test1')
19          ciphertext += ctx.update('test2')
20          ciphertext += ctx.final()
21  
22          ctx2 = pyelliptic.Cipher("secretkey", iv, 0, ciphername='aes-256-cfb')
23          print ctx2.ciphering(ciphertext)
24      """
25      def __init__(self, key, iv, do, ciphername='aes-256-cbc'):
26          """
27          do == 1 => Encrypt; do == 0 => Decrypt
28          """
29          self.cipher = OpenSSL.get_cipher(ciphername)
30          self.ctx = OpenSSL.EVP_CIPHER_CTX_new()
31          if do == 1 or do == 0:
32              k = OpenSSL.malloc(key, len(key))
33              IV = OpenSSL.malloc(iv, len(iv))
34              OpenSSL.EVP_CipherInit_ex(
35                  self.ctx, self.cipher.get_pointer(), 0, k, IV, do)
36          else:
37              raise Exception("RTFM ...")
38  
39      @staticmethod
40      def get_all_cipher():
41          """
42          static method, returns all ciphers available
43          """
44          return list(OpenSSL.cipher_algo.keys())
45  
46      @staticmethod
47      def get_blocksize(ciphername):
48          """This Method returns cipher blocksize"""
49          cipher = OpenSSL.get_cipher(ciphername)
50          return cipher.get_blocksize()
51  
52      @staticmethod
53      def gen_IV(ciphername):
54          """Generate random initialization vector"""
55          cipher = OpenSSL.get_cipher(ciphername)
56          return OpenSSL.rand(cipher.get_blocksize())
57  
58      def update(self, input):
59          """Update result with more data"""
60          i = OpenSSL.c_int(0)
61          buffer = OpenSSL.malloc(b"", len(input) + self.cipher.get_blocksize())
62          inp = OpenSSL.malloc(input, len(input))
63          if OpenSSL.EVP_CipherUpdate(self.ctx, OpenSSL.byref(buffer),
64                                      OpenSSL.byref(i), inp, len(input)) == 0:
65              raise Exception("[OpenSSL] EVP_CipherUpdate FAIL ...")
66          return buffer.raw[0:i.value]  # pylint: disable=invalid-slice-index
67  
68      def final(self):
69          """Returning the final value"""
70          i = OpenSSL.c_int(0)
71          buffer = OpenSSL.malloc(b"", self.cipher.get_blocksize())
72          if (OpenSSL.EVP_CipherFinal_ex(self.ctx, OpenSSL.byref(buffer),
73                                         OpenSSL.byref(i))) == 0:
74              raise Exception("[OpenSSL] EVP_CipherFinal_ex FAIL ...")
75          return buffer.raw[0:i.value]  # pylint: disable=invalid-slice-index
76  
77      def ciphering(self, input):
78          """
79          Do update and final in one method
80          """
81          buff = self.update(input)
82          return buff + self.final()
83  
84      def __del__(self):
85          # pylint: disable=protected-access
86          if OpenSSL._hexversion > 0x10100000 and not OpenSSL._libreSSL:
87              OpenSSL.EVP_CIPHER_CTX_reset(self.ctx)
88          else:
89              OpenSSL.EVP_CIPHER_CTX_cleanup(self.ctx)
90          OpenSSL.EVP_CIPHER_CTX_free(self.ctx)