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         if NACL_VERSION < "1.1.0":
  55             nonce = random(Box.NONCE_SIZE)
  56             cipher = box.encrypt(plain, nonce)
  57         else:
  58             cipher = box.encrypt(plain)
  59         box = None
  60
  61         return cipher
  62
  63     def asymmetric_decrypt(self, privkey, pubkey, cipher):
  64         box = Box(privkey, pubkey)
  65         plain = box.decrypt(cipher)
  66         box = None
  67
  68         return plain
  69
  70     def get_random_key(self):
  71         return random(SecretBox.KEY_SIZE)
  72
  73     def sanitize_key(self, key):
  74         if not isinstance(key, bytes):
  75             key = key.encode('utf-8')
  76         size = len(key)
  77         if size < SecretBox.KEY_SIZE:
  78             """ We must pad """
  79             newkey = key + bytes(SecretBox.KEY_SIZE - size)
  80         elif size > SecretBox.KEY_SIZE:
  81             newkey = key[:SecretBox.KEY_SIZE]
  82         else:
  83             newkey = key
  84
  85
  86         return newkey
  87
  88     def get_key_pair(self):
  89         privkey = PrivateKey.generate()
  90         pubkey = privkey.public_key
  91
  92         return (privkey, pubkey)
  93
  94     def generate_hash(self, key):
  95         if not isinstance(key, bytes):
  96             key = key.encode('utf-8')
  97         HASHER = nacl.hash.sha512
  98         digest = HASHER(key, encoder=HexEncoder)
  99
 100         return digest.decode()
 101
 102     def create_EncryptedMessage(self, payload):
 103         nonce = payload[:SecretBox.NONCE_SIZE]
 104         ciphertext = payload[SecretBox.NONCE_SIZE:]
 105
 106         return EncryptedMessage._from_parts(
 107             nonce, ciphertext,  nonce + ciphertext)