krackattack: note that HANDSHAKE_TRANSMIT_INTERVAL must be same in script and hostapd

krackattack/krack-test-client.py

@@ -109,6 +109,7 @@ the 4-way handshake or group key handshake, take the following steps:
 # - Individual test to see if the client accepts replayed broadcast traffic (without performing key reinstallation)
 
 # After how many seconds a new message 3, or new group key message 1, is sent.
+# This value must match the one in `../src/ap/wpa_auth.c` (same variable name).
 HANDSHAKE_TRANSMIT_INTERVAL = 2
 
 #### Basic output and logging functionality ####
@@ -280,7 +281,7 @@ class ClientState():
 		if payload.startswith("\xAA\xAA\x03\x00\x00\x00"):
 			# On some kernels, the virtual interface associated to the real AP interface will return
 			# frames where the payload is already decrypted. So if the payload seems decrypted, just
-			# extract the full plaintext of the frame.
+			# extract the full plaintext from the frame.
 			plaintext = payload
 		else:
 			client    = self.mac

src/ap/wpa_auth.c

@@ -55,10 +55,11 @@ static void wpa_group_put(struct wpa_authenticator *wpa_auth,
 			  struct wpa_group *group);
 
 #ifdef KRACK_TEST_CLIENT
+#define HANDSHAKE_TRANSMIT_INTERVAL 2
 static const u32 dot11RSNAConfigGroupUpdateCount = 4000;
 static const u32 dot11RSNAConfigPairwiseUpdateCount = 4000;
-static const u32 eapol_key_timeout_first = 2000; /* ms */
-static const u32 eapol_key_timeout_subseq = 2000; /* ms */
+static const u32 eapol_key_timeout_first = HANDSHAKE_TRANSMIT_INTERVAL * 1000; /* ms */
+static const u32 eapol_key_timeout_subseq = HANDSHAKE_TRANSMIT_INTERVAL * 1000; /* ms */
 #else
 static const u32 dot11RSNAConfigGroupUpdateCount = 4;
 static const u32 dot11RSNAConfigPairwiseUpdateCount = 4;
@@ -335,7 +336,7 @@ static void wpa_rekey_gtk(void *eloop_ctx, void *timeout_ctx)
 void poc_start_testing_group_handshake(struct wpa_authenticator *wpa_auth)
 {
 	// Start to periodically execute the group key handshake every 2 seconds
-	wpa_auth->conf.wpa_group_rekey = 2;
+	wpa_auth->conf.wpa_group_rekey = HANDSHAKE_TRANSMIT_INTERVAL;
 	eloop_cancel_timeout(wpa_rekey_gtk, wpa_auth, NULL);
 	eloop_register_timeout(wpa_auth->conf.wpa_group_rekey,
 			       0, wpa_rekey_gtk, wpa_auth, NULL);