Implement sendMessage and receiveMessage

messenger.py

@@ -3,7 +3,9 @@ import pickle
 import string
 import hmac
 from dataclasses import dataclass
+from types import SimpleNamespace
 
+from cryptography.exceptions import InvalidTag
 from cryptography.hazmat.primitives import hashes, serialization
 from cryptography.hazmat.primitives.asymmetric import ec
 from cryptography.hazmat.primitives.ciphers.aead import AESGCM
@@ -170,12 +172,28 @@ class MessengerClient:
         self.certs[name] = public_key
 
     def sendMessage(self, name, message):
-        raise Exception("not implemented!")
-        return
+        state = self.conns.get(name)
+        if state is None:
+            state = SimpleNamespace()
+            self.conns[name] = state
+            initial_secret = DH(self.dh, self.certs[name])
+            self.RatchetInitAlice(state, initial_secret, self.certs[name])
+        plaintext = message.encode("utf-8")
+        return self.RatchetEncrypt(state, plaintext, b"")
 
     def receiveMessage(self, name, header, ciphertext):
-        raise Exception("not implemented!")
-        return
+        state = self.conns.get(name)
+        if state is None:
+            state = SimpleNamespace()
+            initial_secret = DH(self.dh, self.certs[name])
+            self.conns[name] = state
+            self.RatchetInitBob(state, initial_secret, self.dh)
+        try:
+            plaintext = self.RatchetDecrypt(state, header, ciphertext, b"")
+        except InvalidTag:
+            return None
+        return plaintext.decode("utf-8")
+
 
     # this is technically hybrid encryption instead of just el gamal but I blame the instructions instead of myself
     # maybe i'll change this if I want to use a late day
@@ -204,4 +222,3 @@ class MessengerClient:
             "ciphertext": ciphertext
         }
         return plaintext.decode("latin1"), pickle.dumps(data)
-