crypto.py
author Sylvain Thénault <sylvain.thenault@logilab.fr>
Thu, 15 Apr 2010 19:38:24 +0200
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"""Simple cryptographic routines, based on python-crypto.
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:organization: Logilab
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:copyright: 2009-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
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:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
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:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
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"""
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__docformat__ = "restructuredtext en"
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from pickle import dumps, loads
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from base64 import b64encode, b64decode
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from Crypto.Cipher import Blowfish
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_CYPHERERS = {}
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def _cypherer(seed):
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    try:
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        return _CYPHERERS[seed]
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    except KeyError:
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        _CYPHERERS[seed] = Blowfish.new(seed, Blowfish.MODE_ECB)
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        return _CYPHERERS[seed]
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def encrypt(data, seed):
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    string = dumps(data)
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    string = string + '*' * (8 - len(string) % 8)
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    string = b64encode(_cypherer(seed).encrypt(string))
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    return unicode(string)
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def decrypt(string, seed):
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    # pickle ignores trailing characters so we do not need to strip them off
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    string = _cypherer(seed).decrypt(b64decode(string))
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    return loads(string)