def test_validate_invalid_message_returns_false(self):
plaintext = b"You turn yourself around. That's what it's all about."
key = b"Hokey Pokey"
authenticated = MAC.generate(plaintext, key, SHA1)
wrong_key = b"Oh no this is the wrong key"
self.assertFalse(MAC.validate(authenticated, wrong_key, SHA1))
def test_length_extension_nominal_case(self):
key = b"I'm gettin' rid of Britta"
plaintext = b"I'm gettin' rid of the B"
message = MAC.generate(plaintext, key, SHA1)
newtext = b"She's a no good B"
newmessage = length_extension(message, newtext,
lambda msg: MAC.validate(msg, key, SHA1))
self.assertTrue(newmessage.endswith(newtext))
self.assertTrue(MAC.validate(newmessage, key, SHA1))
def test_length_extension_keysize_not_found_returns_none(self):
key = b"I'm gettin' rid of Britta"
plaintext = b"I'm gettin' rid of the B"
message = MAC.generate(plaintext, key, SHA1)
newtext = b"She's a no good B"
newmessage = length_extension(message, newtext,
lambda msg: MAC.validate(msg, key, SHA1),
5)
self.assertIsNone(newmessage)
def main():
"""
append payload to message while maintaining a valid MAC
"""
cookie = (b"comment1=cooking%20MCs;userdata=foo;comment2=%20like%20a%20"
b"pound%20of%20bacon")
key = rand_bytes_gen(random.randint(0, 128))
authenticated_cookie = MAC.generate(cookie, key, SHA1)
def validation_oracle(msg):
return MAC.validate(msg, key, SHA1)
payload = b";admin=true"
attack_cookie = length_extension(
authenticated_cookie,
payload,
validation_oracle
)
assert MAC.validate(attack_cookie, key, SHA1)
print(attack_cookie)
def validation_oracle(msg):
return MAC.validate(msg, key, SHA1)
def test_generate_validate_integration(self):
plaintext = b"You turn yourself around. That's what it's all about."
key = b"Hokey Pokey"
authenticated = MAC.generate(plaintext, key, SHA1)
self.assertTrue(MAC.validate(authenticated, key, SHA1))
def test_validate_message_less_than_20_bytes_returns_false(self):
self.assertFalse(MAC.validate(bytes(19), b'', SHA1))