def test_invalid_verify(self, backend):
key = b"2b7e151628aed2a6abf7158809cf4f3c"
cmac = CMAC(AES(key), backend)
cmac.update(b"6bc1bee22e409f96e93d7e117393172a")
with pytest.raises(InvalidSignature):
cmac.verify(b"foobar")
def test_buffer_protocol(self, backend):
key = bytearray(b"2b7e151628aed2a6abf7158809cf4f3c")
cmac = CMAC(AES(key), backend)
cmac.update(b"6bc1bee22e409f96e93d7e117393172a")
assert cmac.finalize() == binascii.unhexlify(
b"a21e6e647bfeaf5ca0a5e1bcd957dfad"
)
def test_aes_generate(self, backend, params):
key = params["key"]
message = params["message"]
output = params["output"]
cmac = CMAC(AES(binascii.unhexlify(key)), backend)
cmac.update(binascii.unhexlify(message))
assert binascii.hexlify(cmac.finalize()) == output
def test_aes_verify(self, backend, params):
key = params["key"]
message = params["message"]
output = params["output"]
cmac = CMAC(AES(binascii.unhexlify(key)), backend)
cmac.update(binascii.unhexlify(message))
assert cmac.verify(binascii.unhexlify(output)) is None
def test_aes_cmac(backend, wycheproof):
key = binascii.unhexlify(wycheproof.testcase["key"])
msg = binascii.unhexlify(wycheproof.testcase["msg"])
tag = binascii.unhexlify(wycheproof.testcase["tag"])
# skip truncated tags, which we don't support in the API
if wycheproof.valid and len(tag) == 16:
ctx = CMAC(AES(key), backend)
ctx.update(msg)
ctx.verify(tag)
elif len(key) not in [16, 24, 32]:
with pytest.raises(ValueError):
CMAC(AES(key), backend)
else:
ctx = CMAC(AES(key), backend)
ctx.update(msg)
with pytest.raises(InvalidSignature):
ctx.verify(tag)
def test_verify_reject_unicode(self, backend):
key = b"2b7e151628aed2a6abf7158809cf4f3c"
cmac = CMAC(AES(key), backend)
with pytest.raises(TypeError):
cmac.update("")
with pytest.raises(TypeError):
cmac.verify("")
def test_copy():
backend = DummyCMACBackend([AES])
copied_ctx = pretend.stub()
pretend_ctx = pretend.stub(copy=lambda: copied_ctx)
key = b"2b7e151628aed2a6abf7158809cf4f3c"
cmac = CMAC(AES(key), backend=backend, ctx=pretend_ctx)
assert cmac._backend is backend
assert cmac.copy()._backend is backend
def test_copy():
@utils.register_interface(CMACBackend)
class PretendBackend(object):
pass
pretend_backend = PretendBackend()
copied_ctx = pretend.stub()
pretend_ctx = pretend.stub(copy=lambda: copied_ctx)
key = b"2b7e151628aed2a6abf7158809cf4f3c"
cmac = CMAC(AES(key), backend=pretend_backend, ctx=pretend_ctx)
assert cmac._backend is pretend_backend
assert cmac.copy()._backend is pretend_backend
def test_raises_after_finalize(self, backend):
key = b"2b7e151628aed2a6abf7158809cf4f3c"
cmac = CMAC(AES(key), backend)
cmac.finalize()
with pytest.raises(AlreadyFinalized):
cmac.update(b"foo")
with pytest.raises(AlreadyFinalized):
cmac.copy()
with pytest.raises(AlreadyFinalized):
cmac.finalize()
def test_3des_generate(self, backend, params):
key1 = params["key1"]
key2 = params["key2"]
key3 = params["key3"]
key = key1 + key2 + key3
message = params["message"]
output = params["output"]
cmac = CMAC(TripleDES(binascii.unhexlify(key)), backend)
cmac.update(binascii.unhexlify(message))
assert binascii.hexlify(cmac.finalize()) == output
def test_3des_verify(self, backend, params):
key1 = params["key1"]
key2 = params["key2"]
key3 = params["key3"]
key = key1 + key2 + key3
message = params["message"]
output = params["output"]
cmac = CMAC(TripleDES(binascii.unhexlify(key)), backend)
cmac.update(binascii.unhexlify(message))
assert cmac.verify(binascii.unhexlify(output)) is None
def mac(key, msg):
"""
Default MAC function (CMAC using AES-128).
Args:
key: key for MAC creation.
msg: Plaintext to be MACed, as a bytes object.
Returns:
MAC output, as a bytes object.
Raises:
ValueError: An error occurred when key is NULL or ciphertext is NULL.
"""
if key is None:
raise ValueError('Key is NULL.')
elif msg is None:
raise ValueError('Message is NULL.')
else:
cobj = CMAC(AES(key), backend=default_backend())
cobj.update(msg)
return cobj.finalize()
def __init__(self, key, nonce, mac_key):
self._aes = Cipher(algorithms.AES(key), modes.CTR(nonce),
default_backend()).decryptor()
self._mac = CMAC(algorithms.AES(mac_key), default_backend())
def aes_cmac(key, data):
backend = default_backend()
cmac = CMAC(algorithms.AES(key), backend=backend)
cmac.update(data)
return cmac.finalize()
def test_invalid_backend():
key = b"2b7e151628aed2a6abf7158809cf4f3c"
pretend_backend = object()
with raises_unsupported_algorithm(_Reasons.BACKEND_MISSING_INTERFACE):
CMAC(AES(key), pretend_backend)
def test_copy_with_backend(self, backend):
key = b"2b7e151628aed2a6abf7158809cf4f3c"
cmac = CMAC(AES(key), backend)
cmac.update(b"6bc1bee22e409f96e93d7e117393172a")
copy_cmac = cmac.copy()
assert cmac.finalize() == copy_cmac.finalize()
def test_invalid_algorithm(self, backend):
key = b"0102030405"
with pytest.raises(TypeError):
CMAC(ARC4(key), backend)