Create wallet.js

static/wallet.js

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+// 簡易ED25519ウォレット（デモ用）
+// 鍵は localStorage に保存（本番はセキュアストレージやOSキーチェーン等を検討）
+const LS_KEY = 'demo_wallet_ed25519';
+
+function toBase58(bytes){ return bs58.encode(bytes); }
+function fromBase58(str){ return bs58.decode(str); }
+
+// 軽量 Base58（必要部分のみ）
+const bs58 = (function(){
+  const ALPHABET = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';
+  const ALPHABET_MAP = new Uint8Array(256); ALPHABET_MAP.fill(255);
+  for (let i = 0; i < ALPHABET.length; i++) ALPHABET_MAP[ALPHABET.charCodeAt(i)] = i;
+  function encode(buffer){
+    if (buffer.length === 0) return '';
+    let zeros = 0, i = 0; while (i < buffer.length && buffer[i] === 0) { zeros++; i++; }
+    const size = ((buffer.length - i) * 138 / 100 + 1) >>> 0; const b58 = new Uint8Array(size);
+    let length = 0;
+    while (i < buffer.length){
+      let carry = buffer[i]; let j = 0;
+      for (let k = size - 1; (carry !== 0 || j < length) && (k >= 0); k--, j++){
+        carry += 256 * b58[k]; b58[k] = carry % 58; carry = (carry / 58) | 0;
+      }
+      length = j; i++;
+    }
+    let j = size - length; while (j < size && b58[j] === 0) j++;
+    let str = '1'.repeat(zeros) + Array.from(b58.slice(j), (c) => '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'[c]).join('');
+    return str;
+  }
+  function decode(string){
+    if (string.length === 0) return new Uint8Array();
+    let zeros = 0, i = 0; while (i < string.length && string[i] === '1') { zeros++; i++; }
+    const size = ((string.length - i) * 733 / 1000 + 1) >>> 0; const b256 = new Uint8Array(size);
+    let length = 0;
+    while (i < string.length){
+      let carry = ALPHABET_MAP[string.charCodeAt(i)]; if (carry === 255) throw new Error('invalid base58');
+      let j = 0;
+      for (let k = size - 1; (carry !== 0 || j < length) && (k >= 0); k--, j++){
+        carry += 58 * b256[k]; b256[k] = carry % 256; carry = (carry / 256) | 0;
+      }
+      length = j; i++;
+    }
+    let j = size - length; while (j < size && b256[j] === 0) j++;
+    const out = new Uint8Array(zeros + (size - j)); out.fill(0, 0, zeros); out.set(b256.slice(j), zeros); return out;
+  }
+  return { encode, decode };
+})();
+
+function getOrCreateWallet(){
+  const stored = localStorage.getItem(LS_KEY);
+  if (stored){ return JSON.parse(stored); }
+  const kp = nacl.sign.keyPair();
+  const address = toBase58(kp.publicKey);
+  const wallet = { address, publicKey: Array.from(kp.publicKey), secretKey: Array.from(kp.secretKey) };
+  localStorage.setItem(LS_KEY, JSON.stringify(wallet));
+  return wallet;
+}
+
+function getWallet(){
+  const stored = localStorage.getItem(LS_KEY);
+  return stored ? JSON.parse(stored) : null;
+}
+
+async function signMessage(message){
+  const w = getWallet() || getOrCreateWallet();
+  const secret = new Uint8Array(w.secretKey);
+  const sig = nacl.sign.detached(new TextEncoder().encode(message), secret);
+  return btoa(String.fromCharCode(...sig)); // base64
+}
+
+window.Wallet = { getOrCreateWallet, getWallet, signMessage };