python: Add Short Authentication String bindings.

This patch adds bindings to the SAS part of the Olm library contained in
the sas.h header file.

Signed-off-by: Damir Jelić <poljar@termina.org.uk>

1 files changed, 82 insertions, 0 deletions

diff --git a/python/tests/sas_test.py b/python/tests/sas_test.py
new file mode 100644
index 0000000..05013b7
--- /dev/null
+++ b/python/tests/sas_test.py
@@ -0,0 +1,82 @@
+from builtins import bytes
+
+import pytest
+
+from olm import OlmSasError, Sas
+
+MESSAGE = "Test message"
+EXTRA_INFO = "extra_info"
+
+
+class TestClass(object):
+    def test_sas_creation(self):
+        sas = Sas()
+        assert sas.pubkey
+
+    def test_other_key_setting(self):
+        sas_alice = Sas()
+        sas_bob = Sas()
+
+        assert not sas_alice.other_key_set
+        sas_alice.set_their_pubkey(sas_bob.pubkey)
+        assert sas_alice.other_key_set
+
+    def test_bytes_generating(self):
+        sas_alice = Sas()
+        sas_bob = Sas(sas_alice.pubkey)
+
+        assert sas_bob.other_key_set
+
+        with pytest.raises(OlmSasError):
+            sas_alice.generate_bytes(EXTRA_INFO, 5)
+
+        sas_alice.set_their_pubkey(sas_bob.pubkey)
+
+        with pytest.raises(ValueError):
+            sas_alice.generate_bytes(EXTRA_INFO, 0)
+
+        alice_bytes = sas_alice.generate_bytes(EXTRA_INFO, 5)
+        bob_bytes = sas_bob.generate_bytes(EXTRA_INFO, 5)
+
+        assert alice_bytes == bob_bytes
+
+    def test_mac_generating(self):
+        sas_alice = Sas()
+        sas_bob = Sas()
+
+        with pytest.raises(OlmSasError):
+            sas_alice.calculate_mac(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(MESSAGE, EXTRA_INFO)
+        bob_mac = sas_bob.calculate_mac(MESSAGE, EXTRA_INFO)
+
+        assert alice_mac == bob_mac
+
+    def test_cross_language_mac(self):
+        """Test MAC generating with a predefined key pair.
+
+        This test imports a private and public key from the C test and checks
+        if we are getting the same MAC that the C code calculated.
+        """
+        alice_private = [
+            0x77, 0x07, 0x6D, 0x0A, 0x73, 0x18, 0xA5, 0x7D,
+            0x3C, 0x16, 0xC1, 0x72, 0x51, 0xB2, 0x66, 0x45,
+            0xDF, 0x4C, 0x2F, 0x87, 0xEB, 0xC0, 0x99, 0x2A,
+            0xB1, 0x77, 0xFB, 0xA5, 0x1D, 0xB9, 0x2C, 0x2A
+        ]
+
+        bob_key = "3p7bfXt9wbTTW2HC7OQ1Nz+DQ8hbeGdNrfx+FG+IK08"
+        message = "Hello world!"
+        extra_info = "MAC"
+        expected_mac = "2nSMTXM+TStTU3RUVTNSVVZUTlNWVlpVVGxOV1ZscFY"
+
+        sas_alice = Sas()
+        sas_alice._create_sas(bytes(alice_private), 32)
+        sas_alice.set_their_pubkey(bob_key)
+
+        alice_mac = sas_alice.calculate_mac(message, extra_info)
+
+        assert alice_mac == expected_mac