def test_CMAC_verify(self):
# test CMAC verification function
key = Fernet.generate_key()
fernet = Fernet(key)
# test against the cryptography.io library APIs
for i in range(20):
M = os.urandom(i)
K = os.urandom(16)
# use library API generation
c = cmac.CMAC(algorithms.AES(K), backend=default_backend())
c.update(M)
lib_cmac = c.finalize()
# verify a library generated cmac
assert fernet._AES_CMAC_verify(K, M, len(M), lib_cmac)
# verify against our own API
cmac_ = fernet._AES_CMAC_generate(K, M, len(M))
assert fernet._AES_CMAC_verify(K, M, len(M), cmac_)
# # library verify our generated cmac
c = cmac.CMAC(algorithms.AES(K), backend=default_backend())
c.update(M)
try:
c.verify(cmac_)
except Exception:
raise Exception
