62 lines
2.2 KiB
Python
62 lines
2.2 KiB
Python
# -*- coding: utf-8 -*-
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#
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# Copyright 2015 Bahtiar `kalkin-` Gadimov <bahtiar@gadimov.de>
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#
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# This file is part of python-omemo library.
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#
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# The python-omemo library is free software: you can redistribute it and/or
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# modify it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or (at your
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# option) any later version.
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#
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# python-omemo is distributed in the hope that it will be useful, but WITHOUT ANY
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# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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# A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License along with
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# the python-omemo library. If not, see <http://www.gnu.org/licenses/>.
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#
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import os
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from cryptography.hazmat.primitives.ciphers import Cipher
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from cryptography.hazmat.primitives.ciphers import algorithms
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from cryptography.hazmat.primitives.ciphers.modes import GCM
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# On Windows we have to import a specific backend because the
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# default_backend() mechanism doesnt work in Gajim for Windows.
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# Its because of how Gajim is build with cx_freeze
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if os.name == 'nt':
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from cryptography.hazmat.backends.openssl import backend
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else:
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from cryptography.hazmat.backends import default_backend
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def aes_decrypt(key, iv, payload):
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""" Use AES128 GCM with the given key and iv to decrypt the payload. """
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data = payload[:-16]
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tag = payload[-16:]
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if os.name == 'nt':
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_backend = backend
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else:
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_backend = default_backend()
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decryptor = Cipher(
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algorithms.AES(key),
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GCM(iv, tag=tag),
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backend=_backend).decryptor()
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return decryptor.update(data) + decryptor.finalize()
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def aes_encrypt(key, iv, plaintext):
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""" Use AES128 GCM with the given key and iv to encrypt the plaintext. """
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if os.name == 'nt':
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_backend = backend
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else:
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_backend = default_backend()
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encryptor = Cipher(
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algorithms.AES(key),
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GCM(iv),
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backend=_backend).encryptor()
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return encryptor.update(plaintext) + encryptor.finalize() + encryptor.tag
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