From 775d4a84f36d4d5d0700e9c44dfa4114a0cc022c Mon Sep 17 00:00:00 2001
From: Sadeep Madurange <sadeep@asciimx.com>
Date: Sun, 27 Apr 2025 13:16:46 +0800
Subject: Yay! working with session key encryption.

---
 lock/bend.c | 19 ++++++++++++++-----
 lock/fend.c | 44 +++++++++++++++++++++++++++-----------------
 2 files changed, 41 insertions(+), 22 deletions(-)

diff --git a/lock/bend.c b/lock/bend.c
index d7459eb..3957c55 100644
--- a/lock/bend.c
+++ b/lock/bend.c
@@ -36,7 +36,6 @@ static char tab[] = {
 	'P', 'f', ':', 'B', ']', 'Y', '^', 'F', '%', 'C', 'x'
 };
 
-static uint8_t sync = 0;
 static volatile uint8_t rxd = 0;
 static uint16_t tablen = sizeof(tab) / sizeof(tab[0]);
 
@@ -129,10 +128,20 @@ int main(void)
 			radio_recv(buf, WDLEN);
 			rxd = 0;
 			xor(KEY, buf, msg, WDLEN);
-			if (memcmp(msg, LOCK, WDLEN) == 0)
-				lock();
-			else if (memcmp(msg, UNLOCK, WDLEN) == 0)
-				unlock();
+			if (memcmp(msg, SYN, WDLEN) == 0) {
+				keygen(key, WDLEN);
+				xor(KEY, key, buf, WDLEN);
+				radio_sendto(txaddr, buf, WDLEN);
+			} else {
+				xor(key, buf, msg, WDLEN);
+				if (memcmp(msg, LOCK, WDLEN) == 0) {
+					lock();
+					keydel(key, WDLEN);
+				} else if (memcmp(msg, UNLOCK, WDLEN) == 0) {
+					unlock();
+					keydel(key, WDLEN);
+				}
+			}
 		}
 	}
 	return 0;
diff --git a/lock/fend.c b/lock/fend.c
index cae6a94..966bfde 100644
--- a/lock/fend.c
+++ b/lock/fend.c
@@ -21,8 +21,8 @@
 #define RX_PCMSK      PCMSK2
 #define RX_PCINTVEC   PCINT2_vect
 
-uint8_t sync = 0;
 static volatile uint8_t rxd = 0;
+static volatile uint8_t sync = 0;
 static volatile uint8_t islock = 0;
 static volatile uint8_t isunlock = 0;
 
@@ -45,6 +45,7 @@ static inline void init_btns(void)
 
 int main(void)
 {
+	uint8_t n;
 	uint8_t rxaddr[ADDRLEN] = { 194, 178, 82 };
 	uint8_t txaddr[ADDRLEN] = { 194, 178, 83 };
 
@@ -58,28 +59,33 @@ int main(void)
 	radio_print_config();
 
 	sei();
+	radio_listen();
 
 	for (;;) {
-		if (islock) {
-			xor(KEY, LOCK, buf, WDLEN);
+		if (!sync && (islock || isunlock)) {
+			xor(KEY, SYN, buf, WDLEN);
 			do {
 				sync = radio_sendto(txaddr, buf, WDLEN);
 				_delay_ms(50);
 			} while (!sync);
-			sync = 0;
-			islock = 0;
-			uart_write_line("sent LOCK");
+			uart_write_line("sent SYN");
 		}
 
-		if (isunlock) {
-			xor(KEY, UNLOCK, buf, WDLEN);
-			do {
-				sync = radio_sendto(txaddr, buf, WDLEN);
-				_delay_ms(50);
-			} while (!sync);
-			sync = 0;
-			isunlock = 0;
-			uart_write_line("sent UNLOCK");
+		if (rxd) {
+			n = radio_recv(buf, WDLEN);
+			rxd = 0;
+			if (sync && (islock || isunlock)) {
+				sync = 0;
+				xor(KEY, buf, key, WDLEN);
+				if (islock) {
+					islock = 0;
+					xor(key, LOCK, buf, WDLEN);
+				} else if (isunlock) {
+					isunlock = 0;
+					xor(key, UNLOCK, buf, WDLEN);
+				}
+				radio_sendto(txaddr, buf, WDLEN);
+			}
 		}
 	}
 	return 0;
@@ -92,12 +98,16 @@ ISR(RX_PCINTVEC)
 
 ISR(INT0_vect)
 {
-	if (is_btn_pressed(PIND, LOCK_PIN))
+	if (is_btn_pressed(PIND, LOCK_PIN)) {
+		sync = 0;
 		islock = 1;
+	}
 }
 
 ISR(INT1_vect)
 {
-	if (is_btn_pressed(PIND, UNLOCK_PIN))
+	if (is_btn_pressed(PIND, UNLOCK_PIN)) {
+		sync = 0;
 		isunlock = 1;
+	}
 }
-- 
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