[Init] Initial commit - NetMesh terminal manager

infrastructure/services/cloudSync/encryptedLocalStorage.ts

@@ -0,0 +1,26 @@
+export async function encryptLocalStorageValue(value: unknown, key: CryptoKey): Promise<string> {
+  const data = new TextEncoder().encode(JSON.stringify(value));
+  const iv = crypto.getRandomValues(new Uint8Array(12));
+  const encrypted = await crypto.subtle.encrypt({ name: 'AES-GCM', iv }, key, data);
+  const combined = new Uint8Array(iv.length + encrypted.byteLength);
+  combined.set(iv);
+  combined.set(new Uint8Array(encrypted), iv.length);
+  let binary = '';
+  const chunkSize = 8192;
+  for (let offset = 0; offset < combined.length; offset += chunkSize) {
+    binary += String.fromCharCode(...combined.subarray(offset, offset + chunkSize));
+  }
+  return btoa(binary);
+}
+
+export async function decryptLocalStorageValue<T>(
+  encoded: string,
+  key: CryptoKey,
+): Promise<T> {
+  const combined = Uint8Array.from(atob(encoded), (character) => character.charCodeAt(0));
+  if (combined.length <= 12) throw new Error('Encrypted local sync record is truncated');
+  const iv = combined.slice(0, 12);
+  const ciphertext = combined.slice(12);
+  const decrypted = await crypto.subtle.decrypt({ name: 'AES-GCM', iv }, key, ciphertext);
+  return JSON.parse(new TextDecoder().decode(decrypted)) as T;
+}