feat: Auto-generate auth secret and enforce HMAC on privileged commands

- Generate 128-bit random auth secret on first boot via hardware RNG,
  persist to NVS, log to serial for retrieval
- Gate destructive commands (OTA, FACTORY, REBOOT, TARGET, AUTH,
  HOSTNAME set) behind HMAC authentication
- Read-only and operational commands remain open for monitoring
- Require WPA2/WPA3 for WiFi AP association (reject open/WEP)

get-started/csi_recv_router/main/app_main.c

@@ -33,6 +33,7 @@
 #include "esp_task_wdt.h"
 #include "esp_pm.h"
 #include "esp_heap_caps.h"
+#include "esp_random.h"
 #include "esp_ota_ops.h"
 #include "esp_https_ota.h"
 #include "esp_partition.h"
@@ -222,6 +223,8 @@ static int64_t  s_alert_heap_last = 0;
 
 /* --- NVS helpers --- */
 
+static esp_err_t config_save_str(const char *key, const char *value);
+
 static void config_load_nvs(void)
 {
     /* Start with Kconfig defaults */
@@ -340,6 +343,18 @@ static void config_load_nvs(void)
         ESP_LOGI(TAG, "NVS: no saved config, using defaults");
     }
 
+    /* Auto-generate auth secret on first boot */
+    if (s_auth_secret[0] == '\0') {
+        uint8_t rand_bytes[16];
+        esp_fill_random(rand_bytes, sizeof(rand_bytes));
+        for (int i = 0; i < 16; i++) {
+            snprintf(s_auth_secret + i * 2, 3, "%02x", rand_bytes[i]);
+        }
+        s_auth_secret[32] = '\0';
+        config_save_str("auth_secret", s_auth_secret);
+        ESP_LOGW(TAG, "AUTH: generated secret: %s (note this for remote access)", s_auth_secret);
+    }
+
     /* Boot counter — always increment, even on first boot */
     nvs_handle_t bh;
     if (nvs_open("csi_config", NVS_READWRITE, &bh) == ESP_OK) {
@@ -1437,6 +1452,19 @@ static const char *auth_verify(const char *input, char *reply, size_t reply_size
     return cmd;
 }
 
+/* --- Privileged command check --- */
+
+static bool cmd_requires_auth(const char *cmd)
+{
+    if (strncmp(cmd, "OTA ", 4) == 0) return true;
+    if (strcmp(cmd, "FACTORY") == 0) return true;
+    if (strcmp(cmd, "REBOOT") == 0) return true;
+    if (strncmp(cmd, "TARGET ", 7) == 0) return true;
+    if (strncmp(cmd, "AUTH ", 5) == 0) return true;
+    if (strncmp(cmd, "HOSTNAME ", 9) == 0) return true;
+    return false;
+}
+
 /* --- Command handler --- */
 
 static void reboot_after_delay(void *arg)
@@ -2443,12 +2471,27 @@ static void cmd_task(void *arg)
 
         ESP_LOGI(TAG, "CMD rx: \"%s\"", rx_buf);
 
-        const char *verified = auth_verify(rx_buf, reply_buf, sizeof(reply_buf));
+        /* Authenticate: HMAC grants full access; plain commands are read-only */
+        const char *cmd = rx_buf;
+        bool authed = false;
         int reply_len;
-        if (verified) {
+
-            reply_len = cmd_handle(verified, reply_buf, sizeof(reply_buf));
+        if (strncmp(rx_buf, "HMAC:", 5) == 0) {
-        } else {
+            cmd = auth_verify(rx_buf, reply_buf, sizeof(reply_buf));
+            if (cmd) {
+                authed = true;
+            }
+        } else if (s_auth_secret[0] == '\0') {
+            authed = true;
+        }
+
+        if (!cmd) {
+            /* HMAC verification failed — error set by auth_verify */
             reply_len = strlen(reply_buf);
+        } else if (!authed && cmd_requires_auth(cmd)) {
+            reply_len = snprintf(reply_buf, sizeof(reply_buf), "ERR AUTH required");
+        } else {
+            reply_len = cmd_handle(cmd, reply_buf, sizeof(reply_buf));
         }
         sendto(sock, reply_buf, reply_len, 0,
                (struct sockaddr *)&src_addr, src_len);

get-started/csi_recv_router/sdkconfig.defaults

@@ -82,3 +82,8 @@ CONFIG_ESP_WIFI_IRAM_OPT=n
 #
 CONFIG_PM_ENABLE=y
 CONFIG_FREERTOS_USE_TICKLESS_IDLE=y
+
+#
+# WiFi Authentication (reject open/WEP APs)
+#
+CONFIG_EXAMPLE_WIFI_AUTH_WPA2_WPA3_PSK=y