Add Device ID to JSON Info

wled00/fcn_declare.h

@@ -401,6 +401,8 @@ uint8_t extractModeSlider(uint8_t mode, uint8_t slider, char *dest, uint8_t maxL
 int16_t extractModeDefaults(uint8_t mode, const char *segVar);
 void checkSettingsPIN(const char *pin);
 uint16_t crc16(const unsigned char* data_p, size_t length);
+String computeSHA1(const String& input);
+String getDeviceId();
 uint16_t beatsin88_t(accum88 beats_per_minute_88, uint16_t lowest = 0, uint16_t highest = 65535, uint32_t timebase = 0, uint16_t phase_offset = 0);
 uint16_t beatsin16_t(accum88 beats_per_minute, uint16_t lowest = 0, uint16_t highest = 65535, uint32_t timebase = 0, uint16_t phase_offset = 0);
 uint8_t beatsin8_t(accum88 beats_per_minute, uint8_t lowest = 0, uint8_t highest = 255, uint32_t timebase = 0, uint8_t phase_offset = 0);

wled00/json.cpp

@@ -1,5 +1,6 @@
 #include "wled.h"
 
+
 #define JSON_PATH_STATE      1
 #define JSON_PATH_INFO       2
 #define JSON_PATH_STATE_INFO 3
@@ -690,13 +691,15 @@ void serializeState(JsonObject root, bool forPreset, bool includeBri, bool segme
   }
 }
 
+
 void serializeInfo(JsonObject root)
 {
   root[F("ver")] = versionString;
   root[F("vid")] = VERSION;
   root[F("cn")] = F(WLED_CODENAME);
   root[F("release")] = releaseString;
   root[F("repo")] = repoString;
+  root[F("deviceId")] = getDeviceId();
 
   JsonObject leds = root.createNestedObject(F("leds"));
   leds[F("count")] = strip.getLengthTotal();

wled00/util.cpp

@@ -3,13 +3,15 @@
 #include "const.h"
 #ifdef ESP8266
 #include "user_interface.h" // for bootloop detection
+#include <Hash.h>            // for SHA1 on ESP8266
 #else
 #include <Update.h>
 #if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(4, 4, 0)
   #include "esp32/rtc.h"    // for bootloop detection
 #elif ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(3, 3, 0)
   #include "soc/rtc.h"
 #endif
+#include "mbedtls/sha1.h"   // for SHA1 on ESP32
 #endif
 
 
@@ -1124,4 +1126,63 @@ uint8_t perlin8(uint16_t x, uint16_t y) {
 
 uint8_t perlin8(uint16_t x, uint16_t y, uint16_t z) {
   return (((perlin3D_raw((uint32_t)x << 8, (uint32_t)y << 8, (uint32_t)z << 8, true) * 2015) >> 10) + 33168) >> 8; //scale to 16 bit, offset, then scale to 8bit
-}
+}
+
+// Platform-agnostic SHA1 computation from String input
+String computeSHA1(const String& input) {
+  #ifdef ESP8266
+    return sha1(input); // ESP8266 has built-in sha1() function
+  #else
+    // ESP32: Compute SHA1 hash using mbedtls
+    unsigned char shaResult[20]; // SHA1 produces 20 bytes
+    mbedtls_sha1_context ctx;
+
+    mbedtls_sha1_init(&ctx);
+    mbedtls_sha1_starts_ret(&ctx);
+    mbedtls_sha1_update_ret(&ctx, (const unsigned char*)input.c_str(), input.length());
+    mbedtls_sha1_finish_ret(&ctx, shaResult);
+    mbedtls_sha1_free(&ctx);
+
+    // Convert to hexadecimal string
+    char hexString[41];
+    for (int i = 0; i < 20; i++) {
+      sprintf(&hexString[i*2], "%02x", shaResult[i]);
+    }
+    hexString[40] = '\0';
+
+    return String(hexString);
+  #endif
+}
+
+// Generate a device ID based on SHA1 hash of MAC address salted with "WLED"
+// Returns: original SHA1 + last 2 chars of double-hashed SHA1 (42 chars total)
+String getDeviceId() {
+  static String cachedDeviceId = "";
+  if (cachedDeviceId.length() > 0) return cachedDeviceId;
+
+  uint8_t mac[6];
+  WiFi.macAddress(mac);
+  char macStr[18];
+  sprintf(macStr, "%02x:%02x:%02x:%02x:%02x:%02x", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
+
+  // The device string is deterministic as it needs to be consistent for the same device, even after a full flash erase
+  // MAC is salted with other consistent device info to avoid rainbow table attacks.
+  // If the MAC address is known by malicious actors, they could precompute SHA1 hashes to impersonate devices,
+  // but as WLED developers are just looking at statistics and not authenticating devices, this is acceptable.
+  // If the usage data was exfiltrated, you could not easily determine the MAC from the device ID without brute forcing SHA1
+#ifdef ESP8266
+  String deviceString = String(macStr) + "WLED" + ESP.getChipId();
+#else
+  String deviceString = String(macStr) + "WLED" + ESP.getChipModel() + ESP.getChipRevision() + ESP.getEfuseMac();
+#endif
+  String firstHash = computeSHA1(deviceString);
+
+  // Second hash: SHA1 of the first hash
+  String secondHash = computeSHA1(firstHash);
+
+  // Concatenate first hash + last 2 chars of second hash
+  cachedDeviceId = firstHash + secondHash.substring(38);
+
+  return cachedDeviceId;
+}
+