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#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""Tests for the AES decrypter object."""
import unittest
from dfvfs.encryption import aes_decrypter
from dfvfs.lib import definitions
from dfvfs.lib import errors
from tests.encryption import test_lib
class AESDecrypterTestCase(test_lib.DecrypterTestCase):
"""Tests for the AES decrypter object."""
_AES_INITIALIZATION_VECTOR = b'This is an IV456'
_AES_KEY = b'This is a key123'
def testInitialization(self):
"""Tests the initialization method."""
# Test missing initialization vector with valid block cipher mode.
try:
aes_decrypter.AESDecrypter(
cipher_mode=definitions.ENCRYPTION_MODE_ECB, key=self._AES_KEY)
except errors.BackEndError:
raise unittest.SkipTest('missing cryptograpy AES support')
# Test missing arguments.
with self.assertRaises(ValueError):
aes_decrypter.AESDecrypter()
# Test unsupported block cipher mode.
with self.assertRaises(ValueError):
aes_decrypter.AESDecrypter(
cipher_mode='bogus', key=self._AES_KEY)
# Test missing initialization vector.
with self.assertRaises(ValueError):
aes_decrypter.AESDecrypter(
cipher_mode=definitions.ENCRYPTION_MODE_CBC, key=self._AES_KEY)
# Test incorrect key size.
with self.assertRaises(ValueError):
aes_decrypter.AESDecrypter(
cipher_mode=definitions.ENCRYPTION_MODE_ECB, key=b'Wrong key size.')
# Test incorrect initialization vector type.
with self.assertRaises(TypeError):
aes_decrypter.AESDecrypter(
cipher_mode=definitions.ENCRYPTION_MODE_CBC,
initialization_vector='Wrong IV type', key=self._AES_KEY)
# Test incorrect initialization vector size.
with self.assertRaises(ValueError):
aes_decrypter.AESDecrypter(
cipher_mode=definitions.ENCRYPTION_MODE_CBC,
initialization_vector=b'Wrong IV size', key=self._AES_KEY)
def testDecrypt(self):
"""Tests the Decrypt method."""
try:
decrypter = aes_decrypter.AESDecrypter(
cipher_mode=definitions.ENCRYPTION_MODE_CBC,
initialization_vector=self._AES_INITIALIZATION_VECTOR,
key=self._AES_KEY)
except errors.BackEndError:
raise unittest.SkipTest('missing cryptograpy AES support')
# Test full decryption.
expected_decrypted_data = b'This is secret encrypted text!!!'
decrypted_data, remaining_encrypted_data = decrypter.Decrypt(
b'2|\x7f\xd7\xff\xbay\xf9\x95?\x81\xc7\xaafV\xceB\x01\xdb8E7\xfe'
b'\x92j\xf0\x1d(\xb9\x9f\xad\x13', finalize=True)
self.assertEqual(decrypted_data, expected_decrypted_data)
self.assertEqual(remaining_encrypted_data, b'')
# Reset decrypter.
try:
decrypter = aes_decrypter.AESDecrypter(
cipher_mode=definitions.ENCRYPTION_MODE_CBC,
initialization_vector=self._AES_INITIALIZATION_VECTOR,
key=self._AES_KEY)
except errors.BackEndError:
raise unittest.SkipTest('missing cryptograpy AES support')
# Test partial decryption.
partial_encrypted_data = (
b'2|\x7f\xd7\xff\xbay\xf9\x95?\x81\xc7\xaafV\xceB\x01\xdb8E7\xfe')
decrypted_data, remaining_encrypted_data = decrypter.Decrypt(
partial_encrypted_data)
self.assertEqual(decrypted_data, b'This is secret e')
self.assertEqual(remaining_encrypted_data, b'B\x01\xdb8E7\xfe')
if __name__ == '__main__':
unittest.main()
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