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.secret import SecretBox
  21 from nacl.public import PrivateKey, Box
  22 from nacl.utils import random, EncryptedMessage
  23 from nacl.encoding import HexEncoder
  24 import nacl.hash
  25
  26 class Cryptonize:
  27     """
  28     Encrypt and decrypt objects
  29     """
  30
  31     def symmetric_encrypt(self, key, plain):
  32         skey = self.sanitize_key(key)
  33         box = SecretBox(skey)
  34         cipher = box.encrypt(plain)
  35         box = skey = None
  36
  37         return cipher
  38
  39     def symmetric_decrypt(self, key, cipher):
  40         skey = self.sanitize_key(key)
  41         box = SecretBox(skey)
  42         plain = box.decrypt(cipher)
  43         box = skey = None
  44
  45         return plain
  46
  47     def asymmetric_encrypt(self, privkey, pubkey, plain):
  48         box = Box(privkey, pubkey)
  49         cipher = box.encrypt(plain)
  50         box = None
  51
  52         return cipher
  53
  54     def asymmetric_decrypt(self, privkey, pubkey, cipher):
  55         box = Box(privkey, pubkey)
  56         plain = box.decrypt(cipher)
  57         box = None
  58
  59         return plain
  60
  61     def get_random_key(self):
  62         return random(SecretBox.KEY_SIZE)
  63
  64     def sanitize_key(self, key):
  65         if not isinstance(key, bytes):
  66             key = key.encode('utf-8')
  67         size = len(key)
  68         if size < SecretBox.KEY_SIZE:
  69             """ We must pad """
  70             newkey = key + bytes(SecretBox.KEY_SIZE - size)
  71         elif size > SecretBox.KEY_SIZE:
  72             newkey = key[:SecretBox.KEY_SIZE]
  73         else:
  74             newkey = key
  75
  76
  77         return newkey
  78
  79     def get_key_pair(self):
  80         privkey = PrivateKey.generate()
  81         pubkey = privkey.public_key
  82
  83         return (privkey, pubkey)
  84
  85     def generate_hash(self, key):
  86         if not isinstance(key, bytes):
  87             key = key.encode('utf-8')
  88         HASHER = nacl.hash.sha512
  89         digest = HASHER(key, encoder=HexEncoder)
  90
  91         return digest.decode()
  92
  93     def create_EncryptedMessage(self, payload):
  94         nonce = payload[:SecretBox.NONCE_SIZE]
  95         ciphertext = payload[SecretBox.NONCE_SIZE:]
  96
  97         return EncryptedMessage._from_parts(
  98             nonce, ciphertext,  nonce + ciphertext)