first commit

server/auth.js

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+// Auth utilities — password hashing (scrypt), tokens, and TOTP MFA.
+// Uses only Node's built-in crypto, no external auth deps.
+const crypto = require('crypto');
+
+// ---- Passwords (scrypt) ----
+function hashPassword(password, salt = crypto.randomBytes(16).toString('hex')) {
+  const hash = crypto.scryptSync(password, salt, 64).toString('hex');
+  return { hash, salt };
+}
+function verifyPassword(password, salt, expectedHash) {
+  const hash = crypto.scryptSync(password, salt, 64).toString('hex');
+  return crypto.timingSafeEqual(Buffer.from(hash), Buffer.from(expectedHash));
+}
+
+// ---- Random tokens ----
+const token = (bytes = 24) => crypto.randomBytes(bytes).toString('hex');
+const id = () => crypto.randomBytes(8).toString('hex');
+const numericCode = (digits = 6) =>
+  String(crypto.randomInt(0, 10 ** digits)).padStart(digits, '0');
+
+// ---- TOTP (RFC 6238), SHA-1, 30s, 6 digits ----
+const B32 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567';
+function base32Encode(buf) {
+  let bits = 0, value = 0, out = '';
+  for (const byte of buf) {
+    value = (value << 8) | byte; bits += 8;
+    while (bits >= 5) { out += B32[(value >>> (bits - 5)) & 31]; bits -= 5; }
+  }
+  if (bits > 0) out += B32[(value << (5 - bits)) & 31];
+  return out;
+}
+function base32Decode(str) {
+  const clean = str.replace(/=+$/, '').toUpperCase();
+  let bits = 0, value = 0; const out = [];
+  for (const ch of clean) {
+    const idx = B32.indexOf(ch);
+    if (idx === -1) continue;
+    value = (value << 5) | idx; bits += 5;
+    if (bits >= 8) { out.push((value >>> (bits - 8)) & 0xff); bits -= 8; }
+  }
+  return Buffer.from(out);
+}
+function newMfaSecret() {
+  return base32Encode(crypto.randomBytes(20));
+}
+function totp(secret, timeStep = Math.floor(Date.now() / 30000)) {
+  const key = base32Decode(secret);
+  const buf = Buffer.alloc(8);
+  buf.writeBigUInt64BE(BigInt(timeStep));
+  const hmac = crypto.createHmac('sha1', key).update(buf).digest();
+  const offset = hmac[hmac.length - 1] & 0xf;
+  const code =
+    ((hmac[offset] & 0x7f) << 24) |
+    ((hmac[offset + 1] & 0xff) << 16) |
+    ((hmac[offset + 2] & 0xff) << 8) |
+    (hmac[offset + 3] & 0xff);
+  return String(code % 1_000_000).padStart(6, '0');
+}
+function verifyTotp(secret, code, window = 1) {
+  if (!/^\d{6}$/.test(String(code || ''))) return false;
+  const step = Math.floor(Date.now() / 30000);
+  for (let i = -window; i <= window; i++) {
+    if (totp(secret, step + i) === String(code)) return true;
+  }
+  return false;
+}
+function otpauthUrl(secret, email, issuer = 'RemoteAccess') {
+  return `otpauth://totp/${encodeURIComponent(issuer)}:${encodeURIComponent(email)}` +
+         `?secret=${secret}&issuer=${encodeURIComponent(issuer)}&algorithm=SHA1&digits=6&period=30`;
+}
+
+module.exports = {
+  hashPassword, verifyPassword, token, id, numericCode,
+  newMfaSecret, totp, verifyTotp, otpauthUrl,
+};