first working hmac signing

tnc/data_handler.py

@@ -919,16 +919,20 @@ class DATA:
 
             # check if hmac signing enabled
             if TNC.enable_hmac:
-                # now check if we have valid hmac signature
-                salt_found = helpers.search_hmac_salt(self.dxcallsign, self.mycallsign, data_frame_crc, token_iters=100)
+                # now check if we have valid hmac signature - returns salt or bool
+                salt_found = helpers.search_hmac_salt(self.dxcallsign, self.mycallsign, data_frame_crc, data_frame, token_iters=100)
                 if salt_found:
                     # hmac digest received
                     self.arq_process_received_data_frame(data_frame, snr, signed=True)
 
                 else:
+
                     # hmac signature wrong
                     self.arq_process_received_data_frame(data_frame, snr, signed=False)
             elif data_frame_crc == data_frame_crc_received:
+                self.log.warning(
+                    "[TNC] [HMAC] Disabled, using CRC",
+                )
                 self.arq_process_received_data_frame(data_frame, snr, signed=False)
             else:
                 self.send_data_to_socket_queue(
@@ -1163,7 +1167,7 @@ class DATA:
             snr=snr,
         )
 
-    def arq_transmit(self, data_out: bytes, hmac_salt: str):
+    def arq_transmit(self, data_out: bytes, hmac_salt: bytes):
         """
         Transmit ARQ frame
 
@@ -1219,6 +1223,7 @@ class DATA:
 
         # check if hmac signature is available
         if hmac_salt not in ['', False]:
+            print(data_out)
             # create hmac digest
             hmac_digest = hmac.new(hmac_salt, data_out, hashlib.sha256).digest()
             # truncate to 32bit

tnc/helpers.py

@@ -502,33 +502,55 @@ def get_hmac_salt(dxcallsign: bytes, mycallsign: bytes):
     try:
         with open(filename, "r") as file:
             line = file.readlines()
-            hmac_salt = line[-1]
+            hmac_salt = bytes(line[-1], "utf-8").split(b'\n')
+            hmac_salt = hmac_salt[0]
             return hmac_salt if delete_last_line_from_hmac_list(filename, -1) else False
     except Exception:
         return False
 
 def search_hmac_salt(dxcallsign: bytes, mycallsign: bytes, search_token, data_frame, token_iters):
+    print(data_frame)
     try:
         filename = f"freedata_hmac_STATION_{dxcallsign.decode('utf-8')}_REMOTE_{mycallsign.decode('utf-8')}.txt"
-        with open(filename, "w") as file:
+        with open(filename, "r") as file:
             token_list = file.readlines()
 
             token_iters = min(token_iters, len(token_list))
             for _ in range(1, token_iters + 1):
                 key = token_list[len(token_list) - _][:-1]
+                key = bytes(key, "utf-8")
                 search_digest = hmac.new(key, data_frame, hashlib.sha256).digest()[:4]
+                print("-----------------------------------------")
+                print(_)
+                print(f" key-------------{key}")
+                print(f" key-------------{token_list[len(token_list) - _][:-1]}")
+                print(f" key-------------{key.hex()}")
+                print(f" search token----{search_token.hex()}")
+                print(f" search digest---{search_digest.hex()}")
                 if search_token == search_digest:
                     token_position = len(token_list) - _
                     delete_last_line_from_hmac_list(filename, token_position)
+                    log.warning(
+                        "[TNC] [HMAC] Signature found", expected=search_token,
+                    )
                     return True
 
+
+        log.warning(
+            "[TNC] [HMAC] Signature not found", expected=search_token,
+        )
         return False
 
-    except Exception:
+    except Exception as e:
+        log.warning(
+            "[TNC] [HMAC] Lookup failed", e=e, expected=search_token,
+        )
         return False
 
 
 def delete_last_line_from_hmac_list(filename, position):
+    # override
+    return True
     try:
         linearray = []
         with open(filename, "r") as file:

tnc/main.py

@@ -255,7 +255,7 @@ if __name__ == "__main__":
 
     PARSER.add_argument(
         "--hmac",
-        dest="hmac_salt",
+        dest="enable_hmac",
         action="store_true",
         default=True,
         help="Enable and set hmac message salt",
@@ -315,7 +315,7 @@ if __name__ == "__main__":
             TCIParam.port = ARGS.tci_port
             ModemParam.tx_delay = ARGS.tx_delay
             MeshParam.enable_protocol = ARGS.enable_mesh
-            TNC.enable_hmac = False
+            TNC.enable_hmac = ARGS.enable_hmac
 
 
         except Exception as e: