stm32/mpbtstackport: Add ER/IR key generation for BTstack pairing.

pi-anl · claude · pi-anl · commit 774cb8810dcc · 2025-06-10T22:21:55.000+10:00
Implements mp_bluetooth_btstack_port_set_er_ir_keys() function using STM32 hardware RNG to generate cryptographically secure Encryption Root (ER) and Identity Root (IR) keys required for Bluetooth pairing and bonding. This resolves the undefined reference error when building STM32 boards with MICROPY_BLUETOOTH_BTSTACK=1 and pairing/bonding enabled. 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com> Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>
diff --git a/ports/stm32/mpbtstackport.c b/ports/stm32/mpbtstackport.c
@@ -37,6 +37,7 @@
 #include "extmod/btstack/btstack_hci_uart.h"
 #include "extmod/btstack/modbluetooth_btstack.h"
 #include "mpbthciport.h"
+#include "rng.h"
 
 void mp_bluetooth_hci_poll_in_ms(uint32_t ms);
 
@@ -159,4 +160,20 @@ void mp_bluetooth_btstack_port_start(void) {
     hci_power_control(HCI_POWER_ON);
 }
 
+#if MICROPY_PY_BLUETOOTH_ENABLE_PAIRING_BONDING
+void mp_bluetooth_btstack_port_set_er_ir_keys(void) {
+    // Generate cryptographically secure ER and IR keys using hardware RNG
+    sm_key_t er_key, ir_key;
+
+    // Use STM32 hardware RNG to generate secure keys
+    for (int i = 0; i < 16; i++) {
+        er_key[i] = (uint8_t)(rng_get() & 0xFF);
+        ir_key[i] = (uint8_t)(rng_get() & 0xFF);
+    }
+
+    sm_set_er(er_key);
+    sm_set_ir(ir_key);
+}
+#endif // MICROPY_PY_BLUETOOTH_ENABLE_PAIRING_BONDING
+
 #endif // MICROPY_PY_BLUETOOTH && MICROPY_BLUETOOTH_BTSTACK
