def runTest(self):
key = b"0" * 16
data = b"\x00\x01\x02"
def get_mv_ro(data):
return memoryview(data)
def get_mv_rw(data):
return memoryview(bytearray(data))
for get_mv in (get_mv_ro, get_mv_rw):
# Data and key can be a memoryview (during initialization)
key_mv = get_mv(key)
data_mv = get_mv(data)
h1 = CMAC.new(key, data, ciphermod=AES)
h2 = CMAC.new(key_mv, data_mv, ciphermod=AES)
if not data_mv.readonly:
key_mv[:1] = b'\xFF'
data_mv[:1] = b'\xFF'
self.assertEqual(h1.digest(), h2.digest())
# Data can be a memoryview (during operation)
data_mv = get_mv(data)
h1 = CMAC.new(key, ciphermod=AES)
h2 = CMAC.new(key, ciphermod=AES)
h1.update(data)
h2.update(data_mv)
if not data_mv.readonly:
data_mv[:1] = b'\xFF'
self.assertEqual(h1.digest(), h2.digest())
def runTest(self):
key = b"0" * 16
data = b"\x00\x01\x02"
# Data and key can be a bytearray (during initialization)
key_ba = bytearray(key)
data_ba = bytearray(data)
h1 = CMAC.new(key, data, ciphermod=AES)
h2 = CMAC.new(key_ba, data_ba, ciphermod=AES)
key_ba[:1] = b'\xFF'
data_ba[:1] = b'\xFF'
self.assertEqual(h1.digest(), h2.digest())
# Data can be a bytearray (during operation)
key_ba = bytearray(key)
data_ba = bytearray(data)
h1 = CMAC.new(key, ciphermod=AES)
h2 = CMAC.new(key, ciphermod=AES)
h1.update(data)
h2.update(data_ba)
data_ba[:1] = b'\xFF'
self.assertEqual(h1.digest(), h2.digest())
def runTest(self):
data_to_mac = get_tag_random("data_to_mac", 128)
key = get_tag_random("key", 16)
ref_mac = CMAC.new(key, msg=data_to_mac, ciphermod=AES).digest()
# Break up in chunks of different length
# The result must always be the same
for chunk_length in 1, 2, 3, 7, 10, 13, 16, 40, 80, 128:
chunks = [
data_to_mac[i:i + chunk_length]
for i in range(0, len(data_to_mac), chunk_length)
]
mac = CMAC.new(key, ciphermod=AES)
for chunk in chunks:
mac.update(chunk)
self.assertEqual(ref_mac, mac.digest())
def test_create_mac(self, tv):
self._id = "Wycheproof MAC creation Test #" + str(tv.id)
try:
tag = CMAC.new(tv.key, tv.msg, ciphermod=AES,
mac_len=tv.tag_size).digest()
except ValueError as e:
if len(tv.key) not in (16, 24, 32) and "key length" in str(e):
return
raise e
if tv.valid:
self.assertEqual(tag, tv.tag)
self.warn(tv)
def test_verify_mac(self, tv):
self._id = "Wycheproof MAC verification Test #" + str(tv.id)
try:
mac = CMAC.new(tv.key, tv.msg, ciphermod=AES, mac_len=tv.tag_size)
except ValueError as e:
if len(tv.key) not in (16, 24, 32) and "key length" in str(e):
return
raise e
try:
mac.verify(tv.tag)
except ValueError:
assert not tv.valid
else:
assert tv.valid
self.warn(tv)
def __init__(self, factory, key, nonce, mac_len, cipher_params):
"""EAX cipher mode"""
self.block_size = factory.block_size
"""The block size of the underlying cipher, in bytes."""
self.nonce = _copy_bytes(None, None, nonce)
"""The nonce originally used to create the object."""
self._mac_len = mac_len
self._mac_tag = None # Cache for MAC tag
# Allowed transitions after initialization
self._next = [
self.update, self.encrypt, self.decrypt, self.digest, self.verify
]
# MAC tag length
if not (4 <= self._mac_len <= self.block_size):
raise ValueError("Parameter 'mac_len' must not be larger than %d" %
self.block_size)
# Nonce cannot be empty and must be a byte string
if len(self.nonce) == 0:
raise ValueError("Nonce cannot be empty in EAX mode")
if not is_buffer(nonce):
raise TypeError("nonce must be bytes, bytearray or memoryview")
self._omac = [
CMAC.new(key,
b'\x00' * (self.block_size - 1) + struct.pack('B', i),
ciphermod=factory,
cipher_params=cipher_params) for i in range(0, 3)
]
# Compute MAC of nonce
self._omac[0].update(self.nonce)
self._signer = self._omac[1]
# MAC of the nonce is also the initial counter for CTR encryption
counter_int = bytes_to_long(self._omac[0].digest())
self._cipher = factory.new(key,
factory.MODE_CTR,
initial_value=counter_int,
nonce=b"",
**cipher_params)
def derive(self):
""""Derive a secret from the vector of components.
:Return: a byte string, as long as the block length of the cipher.
"""
if len(self._last_string) >= 16:
# xorend
final = self._last_string[:-16] + strxor(self._last_string[-16:],
self._cache)
else:
# zero-pad & xor
padded = (self._last_string + b'\x80' + b'\x00' * 15)[:16]
final = strxor(padded, self._double(self._cache))
mac = CMAC.new(self._key,
msg=final,
ciphermod=self._ciphermod,
cipher_params=self._cipher_params)
return mac.digest()
def update(self, item):
"""Pass the next component of the vector.
The maximum number of components you can pass is equal to the block
length of the cipher (in bits) minus 1.
:Parameters:
item : byte string
The next component of the vector.
:Raise TypeError: when the limit on the number of components has been reached.
"""
if self._n_updates == 0:
raise TypeError("Too many components passed to S2V")
self._n_updates -= 1
mac = CMAC.new(self._key,
msg=self._last_string,
ciphermod=self._ciphermod,
cipher_params=self._cipher_params)
self._cache = strxor(self._double(self._cache), mac.digest())
self._last_string = _copy_bytes(None, None, item)