v2

src/wallet.ts

@@ -0,0 +1,41 @@
+export type Wallet = { privateKey: CryptoKey; publicKey: string; address: string };
+const encode = (bytes: ArrayBuffer) => btoa(String.fromCharCode(...new Uint8Array(bytes)));
+
+async function loadOrCreate(): Promise<Wallet> {
+  const db = await new Promise<IDBDatabase>((resolve, reject) => {
+    const request = indexedDB.open('wikideck-wallet', 1);
+    request.onupgradeneeded = () => request.result.createObjectStore('keys');
+    request.onsuccess = () => resolve(request.result);
+    request.onerror = () => reject(new Error('Enable browser storage to create your local wallet.'));
+  });
+  try {
+    const saved = await new Promise<Wallet | undefined>((resolve, reject) => {
+      const req = db.transaction('keys').objectStore('keys').get('identity');
+      req.onsuccess = () => resolve(req.result);
+      req.onerror = () => reject(req.error);
+    });
+    if (saved) return saved;
+    const keys = await crypto.subtle.generateKey({ name: 'ECDSA', namedCurve: 'P-256' }, false, ['sign', 'verify']);
+    const spki = await crypto.subtle.exportKey('spki', keys.publicKey);
+    const digest = new Uint8Array(await crypto.subtle.digest('SHA-256', spki));
+    const wallet = { privateKey: keys.privateKey, publicKey: encode(spki),
+      address: Array.from(digest, b => b.toString(16).padStart(2, '0')).join('') };
+    await new Promise<void>((resolve, reject) => {
+      const tx = db.transaction('keys', 'readwrite');
+      tx.objectStore('keys').put(wallet, 'identity');
+      tx.oncomplete = () => resolve();
+      tx.onerror = () => reject(tx.error);
+    });
+    return wallet;
+  } finally { db.close(); }
+}
+let pending: Promise<Wallet> | undefined;
+export function getWallet(): Promise<Wallet> {
+  return pending ??= (async () => {
+    if (navigator.locks) return await navigator.locks.request('wikideck-wallet-init', loadOrCreate);
+    return loadOrCreate();
+  })().catch(error => { pending = undefined; throw error; });
+}
+export async function sign(wallet: Wallet, message: string): Promise<string> {
+  return encode(await crypto.subtle.sign({ name: 'ECDSA', hash: 'SHA-256' }, wallet.privateKey, new TextEncoder().encode(message)));
+}