cryptonize.py

   1 # -*- coding: utf-8 -*-
   2
   3 # Copyright (c) 2018  Michael Rasmussen <mir@datanom.net>
   4
   5 # This file is part of SecureMail.
   6
   7 # SecureMail is free software: you can redistribute it and/or modify
   8 # it under the terms of the GNU General Public License as published by
   9 # the Free Software Foundation, either version 3 of the License, or
  10 # (at your option) any later version.
  11 #
  12 # SecureMail is distributed in the hope that it will be useful,
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 # GNU General Public License for more details.
  16 #
  17 # You should have received a copy of the GNU General Public License
  18 # along with SecureMail.  If not, see <https://www.gnu.org/licenses/>.
  19
  20 from nacl import __version__ as NACL_VERSION
  21 from nacl.secret import SecretBox
  22 from nacl.public import PrivateKey, Box
  23 from nacl.utils import random, EncryptedMessage
  24 from nacl.encoding import HexEncoder
  25 import nacl.hash
  26
  27 class Cryptonize:
  28     """
  29     Encrypt and decrypt objects
  30     """
  31
  32     def symmetric_encrypt(self, key, plain):
  33         skey = self.sanitize_key(key)
  34         box = SecretBox(skey)
  35         if NACL_VERSION < "1.1.0":
  36             nonce = random(SecretBox.NONCE_SIZE)
  37             cipher = box.encrypt(plain, nonce)
  38         else:
  39             cipher = box.encrypt(plain)
  40         box = skey = None
  41
  42         return cipher
  43
  44     def symmetric_decrypt(self, key, cipher):
  45         skey = self.sanitize_key(key)
  46         box = SecretBox(skey)
  47         plain = box.decrypt(cipher)
  48         box = skey = None
  49
  50         return plain
  51
  52     def asymmetric_encrypt(self, privkey, pubkey, plain):
  53         box = Box(privkey, pubkey)
  54         cipher = box.encrypt(plain)
  55         box = None
  56
  57         return cipher
  58
  59     def asymmetric_decrypt(self, privkey, pubkey, cipher):
  60         box = Box(privkey, pubkey)
  61         plain = box.decrypt(cipher)
  62         box = None
  63
  64         return plain
  65
  66     def get_random_key(self):
  67         return random(SecretBox.KEY_SIZE)
  68
  69     def sanitize_key(self, key):
  70         if not isinstance(key, bytes):
  71             key = key.encode('utf-8')
  72         size = len(key)
  73         if size < SecretBox.KEY_SIZE:
  74             """ We must pad """
  75             newkey = key + bytes(SecretBox.KEY_SIZE - size)
  76         elif size > SecretBox.KEY_SIZE:
  77             newkey = key[:SecretBox.KEY_SIZE]
  78         else:
  79             newkey = key
  80
  81
  82         return newkey
  83
  84     def get_key_pair(self):
  85         privkey = PrivateKey.generate()
  86         pubkey = privkey.public_key
  87
  88         return (privkey, pubkey)
  89
  90     def generate_hash(self, key):
  91         if not isinstance(key, bytes):
  92             key = key.encode('utf-8')
  93         HASHER = nacl.hash.sha512
  94         digest = HASHER(key, encoder=HexEncoder)
  95
  96         return digest.decode()
  97
  98     def create_EncryptedMessage(self, payload):
  99         nonce = payload[:SecretBox.NONCE_SIZE]
 100         ciphertext = payload[SecretBox.NONCE_SIZE:]
 101
 102         return EncryptedMessage._from_parts(
 103             nonce, ciphertext,  nonce + ciphertext)