Commit 32b99b79 authored by poljar's avatar poljar
Browse files

python: Add support for the long KDF MAC calculation.

parent 659eb34f

python/olm/sas.py

+35 −0
Original line number Diff line number Diff line
@@ -220,3 +220,38 @@ class Sas(object): 
            )

        )

        return bytes_to_native_str(ffi.unpack(mac_buffer, mac_length))



    @other_pubkey_set

    def calculate_mac_long_kdf(self, message, extra_info):

        # type: (str, str) -> str

        """Generate a message authentication code based on the shared secret.



        This function should not be used unless compatibility with an older

        non-tagged Olm version is required.



        Args:

            message (str): The message to produce the authentication code for.

            extra_info (str): Extra information to mix in when generating the

                MAC



        Raises OlmSasError on failure.



        """

        byte_message = to_bytes(message)

        byte_info = to_bytes(extra_info)



        mac_length = lib.olm_sas_mac_length(self._sas)

        mac_buffer = ffi.new("char[]", mac_length)



        self._check_error(

            lib.olm_sas_calculate_mac_long_kdf(

                self._sas,

                ffi.from_buffer(byte_message),

                len(byte_message),

                ffi.from_buffer(byte_info),

                len(byte_info),

                mac_buffer,

                mac_length

            )

        )

        return bytes_to_native_str(ffi.unpack(mac_buffer, mac_length))

python/tests/sas_test.py

+17 −0
Original line number Diff line number Diff line
@@ -80,3 +80,20 @@ class TestClass(object): 
        alice_mac = sas_alice.calculate_mac(message, extra_info)



        assert alice_mac == expected_mac



    def test_long_mac_generating(self):

        sas_alice = Sas()

        sas_bob = Sas()



        with pytest.raises(OlmSasError):

            sas_alice.calculate_mac_long_kdf(MESSAGE, EXTRA_INFO)



        sas_alice.set_their_pubkey(sas_bob.pubkey)

        sas_bob.set_their_pubkey(sas_alice.pubkey)



        alice_mac = sas_alice.calculate_mac_long_kdf(MESSAGE, EXTRA_INFO)

        bob_mac = sas_bob.calculate_mac_long_kdf(MESSAGE, EXTRA_INFO)

        bob_short_mac = sas_bob.calculate_mac(MESSAGE, EXTRA_INFO)



        assert alice_mac == bob_mac

        assert alice_mac != bob_short_mac