Python object locker

readme.md

Python object locker

It is python object locker, literally.

Example

from locker import Locker

foo = 'Hello, world!'

locker = Locker('somepassword')
locked = locker.lock(foo)
print 'locked result: {}'.format(locked)

unlocked = locker.unlock(locked)
print 'unlocked result: {}'.format(unlocked)

Remark

Use it with getpass module in your script, then nobody can unlock the locked result without knowing password.

locker.py

try:
    import cPickle as pickle
except ImportError:
    import pickle
import zlib
from Crypto.Cipher import AES
from Crypto.Hash import MD5
from Crypto import Random
from base64 import b64encode, b64decode

class Locker(object):
    AES_BLOCK_SIZE = 16

    def __init__(self, key):
        self._key_md5 = MD5.new(key).hexdigest()

    def lock(self, data):
        try: return self._aes_encrypt(zlib.compress(pickle.dumps(data)))
        except: return None

    def unlock(self, data):
        try: return pickle.loads(zlib.decompress(self._aes_decrypt(data)))
        except: return None

    def _aes_encrypt(self, data):
        iv = Random.new().read(self.AES_BLOCK_SIZE)
        aes = AES.new(self._key_md5, AES.MODE_CBC, iv)
        return b64encode(iv + aes.encrypt(self._pad(data)))

    def _aes_decrypt(self, data):
        data = b64decode(data)
        iv = data[:16]
        aes = AES.new(self._key_md5, AES.MODE_CBC, iv)
        return self._unpad(aes.decrypt(data[16:]))

    def _pad(self, data):
        l = self.AES_BLOCK_SIZE - len(data) % self.AES_BLOCK_SIZE
        return data + chr(l) * l

    def _unpad(self, data):
        return data[:-ord(data[len(data) - 1:])]