test_security.py 文件源码

def test__assures_data_integrity(self):
        self.write_secret()
        testdata = factory.make_bytes(size=10)
        token = fernet_encrypt_psk(testdata)
        bad_token = bytearray(token)
        # Flip a bit in the token, so we can ensure it won't decrypt if it
        # has been corrupted. Subtract 4 to avoid the end of the token; that
        # portion is just padding, and isn't covered by the HMAC.
        byte_to_flip = randint(0, len(bad_token) - 4)
        bit_to_flip = 1 << randint(0, 7)
        bad_token[byte_to_flip] ^= bit_to_flip
        bad_token = bytes(bad_token)
        test_description = ("token=%s; token[%d] ^= 0x%02x" % (
            token.decode("utf-8"), byte_to_flip, bit_to_flip))
        with ExpectedException(InvalidToken, msg=test_description):
            fernet_decrypt_psk(bad_token)