diff --git a/node/rustchain_p2p_gossip.py b/node/rustchain_p2p_gossip.py
index 268526f50..90cdc9013 100644
--- a/node/rustchain_p2p_gossip.py
+++ b/node/rustchain_p2p_gossip.py
@@ -375,6 +375,7 @@ def _sign_message(self, content: str) -> Tuple[str, int]:
 
         hmac_sig: Optional[str] = None
         ed25519_sig: Optional[str] = None
+        key_version = 1
 
         if mode in ("hmac", "dual"):
             hmac_sig = hmac.new(
@@ -383,9 +384,10 @@ def _sign_message(self, content: str) -> Tuple[str, int]:
 
         if mode in ("dual", "ed25519", "strict") and self._keypair is not None:
             ed25519_sig = self._keypair.sign(message.encode())
+            key_version = self._keypair.key_version
 
         from p2p_identity import pack_signature
-        return pack_signature(hmac_sig, ed25519_sig), timestamp
+        return pack_signature(hmac_sig, ed25519_sig, key_version), timestamp
 
     def _verify_signature(self, content: str, signature: str, timestamp: int) -> bool:
         """Verify a message signature.
@@ -480,13 +482,23 @@ def verify_message(self, msg: GossipMessage) -> bool:
         mode = self._signing_mode
 
         from p2p_identity import unpack_signature, verify_ed25519
-        hmac_sig, ed25519_sig = unpack_signature(msg.signature)
+        hmac_sig, ed25519_sig, incoming_version = unpack_signature(msg.signature)
 
         # 1) Try Ed25519 if available AND peer is registered.
         if ed25519_sig and self._peer_registry is not None:
-            pubkey = self._peer_registry.get_pubkey(msg.sender_id)
-            if pubkey and verify_ed25519(pubkey, ed25519_sig, message.encode()):
-                return True
+            entry = self._peer_registry.get_entry(msg.sender_id)
+            pubkey = entry.pubkey_hex if entry else None
+            if pubkey:
+                # Item A: Check key version matches registry
+                if incoming_version != entry.key_version:
+                    logger.warning(
+                        f"Peer {msg.sender_id} key version mismatch: "
+                        f"registry expects v{entry.key_version}, got v{incoming_version}"
+                    )
+                    return False
+
+                if verify_ed25519(pubkey, ed25519_sig, message.encode()):
+                    return True
             # In strict mode, Ed25519 must succeed — no fallback.
             if mode == "strict":
                 return False
@@ -880,16 +892,20 @@ def _handle_get_state(self, msg: GossipMessage) -> Dict:
             "balances": self.balance_crdt.to_dict()
         }
         # Sign the state response so the requester can verify authenticity.
-        # Uses the Phase A signed-content shape (msg_type:sender_id:payload)
-        # so verify_message() on the requester side accepts it.
+        # Generate a synthetic msg_id for the response.
         payload = {"state": state_data}
-        content = self._signed_content(MessageType.STATE.value, self.node_id, payload)
+        state_msg_id = hashlib.sha256(
+            f"STATE:{self.node_id}:{json.dumps(payload, sort_keys=True)}:{time.time()}".encode()
+        ).hexdigest()[:24]
+        content = self._signed_content(MessageType.STATE.value, self.node_id, state_msg_id, 0, payload)
         signature, timestamp = self._sign_message(content)
         return {
             "status": "ok",
             "state": state_data,
             "signature": signature,
             "timestamp": timestamp,
+            "msg_id": state_msg_id,
+            "ttl": 0,
             "sender_id": self.node_id
         }
 
diff --git a/node/tests/test_get_state_arity.py b/node/tests/test_get_state_arity.py
new file mode 100644
index 000000000..20363cf13
--- /dev/null
+++ b/node/tests/test_get_state_arity.py
@@ -0,0 +1,54 @@
+import unittest
+import json
+import os
+import tempfile
+import sqlite3
+from node.rustchain_p2p_gossip import GossipLayer, MessageType, GossipMessage
+
+class TestGetStateArity(unittest.TestCase):
+    def setUp(self):
+        self.db_fd, self.db_path = tempfile.mkstemp()
+        self.gossip = GossipLayer(node_id="test_node", db_path=self.db_path, peers={})
+
+    def tearDown(self):
+        os.close(self.db_fd)
+        os.unlink(self.db_path)
+
+    def test_handle_get_state_no_raise(self):
+        """Assert _handle_get_state runs without TypeError and returns verifiable signature"""
+        # Create a mock GET_STATE message
+        msg = GossipMessage(
+            msg_type=MessageType.GET_STATE.value,
+            msg_id="test_get_state",
+            sender_id="peer_node",
+            timestamp=1234567890,
+            ttl=1,
+            signature="mock_sig",
+            payload={"requester": "peer_node"}
+        )
+        
+        # This should NOT raise TypeError now
+        response = self.gossip._handle_get_state(msg)
+        
+        self.assertEqual(response["status"], "ok")
+        self.assertIn("state", response)
+        self.assertIn("signature", response)
+        self.assertIn("msg_id", response)
+        self.assertIn("ttl", response)
+        
+        # Verify the signature end-to-end
+        # Reconstruction logic used by the requester
+        state_msg = GossipMessage(
+            msg_type=MessageType.STATE.value,
+            msg_id=response["msg_id"],
+            sender_id=response["sender_id"],
+            timestamp=response["timestamp"],
+            ttl=response["ttl"],
+            signature=response["signature"],
+            payload={"state": response["state"]}
+        )
+        
+        self.assertTrue(self.gossip.verify_message(state_msg), "Requester failed to verify state response signature")
+
+if __name__ == "__main__":
+    unittest.main()