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# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.
from __future__ import absolute_import, division, print_function
import binascii
import pytest
from cryptography import utils
from cryptography.exceptions import (
AlreadyFinalized, _Reasons
)
from cryptography.hazmat.backends.interfaces import CipherBackend
from cryptography.hazmat.primitives.ciphers import (
Cipher, algorithms, base, modes
)
from .utils import (
generate_aead_exception_test, generate_aead_tag_exception_test
)
from ...utils import raises_unsupported_algorithm
@utils.register_interface(modes.Mode)
class DummyMode(object):
name = "dummy-mode"
def validate_for_algorithm(self, algorithm):
pass
@utils.register_interface(base.CipherAlgorithm)
class DummyCipher(object):
name = "dummy-cipher"
key_size = None
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestCipher(object):
def test_creates_encryptor(self, backend):
cipher = Cipher(
algorithms.AES(binascii.unhexlify(b"0" * 32)),
modes.CBC(binascii.unhexlify(b"0" * 32)),
backend
)
assert isinstance(cipher.encryptor(), base.CipherContext)
def test_creates_decryptor(self, backend):
cipher = Cipher(
algorithms.AES(binascii.unhexlify(b"0" * 32)),
modes.CBC(binascii.unhexlify(b"0" * 32)),
backend
)
assert isinstance(cipher.decryptor(), base.CipherContext)
def test_instantiate_with_non_algorithm(self, backend):
algorithm = object()
with pytest.raises(TypeError):
Cipher(algorithm, mode=None, backend=backend)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestCipherContext(object):
def test_use_after_finalize(self, backend):
cipher = Cipher(
algorithms.AES(binascii.unhexlify(b"0" * 32)),
modes.CBC(binascii.unhexlify(b"0" * 32)),
backend
)
encryptor = cipher.encryptor()
encryptor.update(b"a" * 16)
encryptor.finalize()
with pytest.raises(AlreadyFinalized):
encryptor.update(b"b" * 16)
with pytest.raises(AlreadyFinalized):
encryptor.finalize()
decryptor = cipher.decryptor()
decryptor.update(b"a" * 16)
decryptor.finalize()
with pytest.raises(AlreadyFinalized):
decryptor.update(b"b" * 16)
with pytest.raises(AlreadyFinalized):
decryptor.finalize()
def test_unaligned_block_encryption(self, backend):
cipher = Cipher(
algorithms.AES(binascii.unhexlify(b"0" * 32)),
modes.ECB(),
backend
)
encryptor = cipher.encryptor()
ct = encryptor.update(b"a" * 15)
assert ct == b""
ct += encryptor.update(b"a" * 65)
assert len(ct) == 80
ct += encryptor.finalize()
decryptor = cipher.decryptor()
pt = decryptor.update(ct[:3])
assert pt == b""
pt += decryptor.update(ct[3:])
assert len(pt) == 80
assert pt == b"a" * 80
decryptor.finalize()
@pytest.mark.parametrize("mode", [DummyMode(), None])
def test_nonexistent_cipher(self, backend, mode):
cipher = Cipher(
DummyCipher(), mode, backend
)
with raises_unsupported_algorithm(_Reasons.UNSUPPORTED_CIPHER):
cipher.encryptor()
with raises_unsupported_algorithm(_Reasons.UNSUPPORTED_CIPHER):
cipher.decryptor()
def test_incorrectly_padded(self, backend):
cipher = Cipher(
algorithms.AES(b"\x00" * 16),
modes.CBC(b"\x00" * 16),
backend
)
encryptor = cipher.encryptor()
encryptor.update(b"1")
with pytest.raises(ValueError):
encryptor.finalize()
decryptor = cipher.decryptor()
decryptor.update(b"1")
with pytest.raises(ValueError):
decryptor.finalize()
@pytest.mark.supported(
only_if=lambda backend: backend.cipher_supported(
algorithms.AES("\x00" * 16), modes.GCM("\x00" * 12)
),
skip_message="Does not support AES GCM",
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestAEADCipherContext(object):
test_aead_exceptions = generate_aead_exception_test(
algorithms.AES,
modes.GCM,
)
test_aead_tag_exceptions = generate_aead_tag_exception_test(
algorithms.AES,
modes.GCM,
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestModeValidation(object):
def test_cbc(self, backend):
with pytest.raises(ValueError):
Cipher(
algorithms.AES(b"\x00" * 16),
modes.CBC(b"abc"),
backend,
)
def test_ofb(self, backend):
with pytest.raises(ValueError):
Cipher(
algorithms.AES(b"\x00" * 16),
modes.OFB(b"abc"),
backend,
)
def test_cfb(self, backend):
with pytest.raises(ValueError):
Cipher(
algorithms.AES(b"\x00" * 16),
modes.CFB(b"abc"),
backend,
)
def test_cfb8(self, backend):
with pytest.raises(ValueError):
Cipher(
algorithms.AES(b"\x00" * 16),
modes.CFB8(b"abc"),
backend,
)
def test_ctr(self, backend):
with pytest.raises(ValueError):
Cipher(
algorithms.AES(b"\x00" * 16),
modes.CTR(b"abc"),
backend,
)
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