feat: unique device id

web/src/util/deviceId.ts

@@ -0,0 +1,31 @@
+export const getDeviceId = async () => {
+  const existing = localStorage.getItem("guard-device-id");
+  if (existing) return existing;
+
+  const fingerprintParts = [
+    navigator.userAgent, // Browser and OS
+    screen.width + "x" + screen.height, // Screen resolution
+    screen.colorDepth, // Color depth
+    Intl.DateTimeFormat().resolvedOptions().timeZone, // Time zone
+    navigator.platform, // OS platform
+    navigator.hardwareConcurrency, // Number of CPU cores
+    navigator.language, // Primary language
+    navigator.maxTouchPoints, // Touch capability
+  ];
+  console.log(fingerprintParts);
+
+  const rawFingerprint = fingerprintParts.join("|");
+  const encoder = new TextEncoder();
+  const data = encoder.encode(rawFingerprint);
+
+  const hashBuffer = await crypto.subtle.digest("SHA-256", data);
+  const hashArray = Array.from(new Uint8Array(hashBuffer));
+
+  const deviceId = hashArray
+    .map((b) => b.toString(16).padStart(2, "0"))
+    .join("");
+
+  localStorage.setItem("guard-device-id", deviceId);
+
+  return deviceId; // A 64-character hex string
+};