KD-MM2

async function generateOneTimePassword(rawKey: Uint8Array, counter: number): Promise<number> {
  const data = new DataView(new ArrayBuffer(8));
  data.setBigUint64(0,  BigInt(Math.floor(counter)), false);

  const algo = { name: 'HMAC', hash: 'SHA-1' };
  const key = await crypto.subtle.importKey('raw', rawKey, algo, false, ['sign']);
  const hmacHash = new Uint8Array(await crypto.subtle.sign(algo, key, data.buffer));

  const offset = hmacHash[hmacHash.byteLength - 1] & 0x0f;
  const hotp = (hmacHash[offset] & 0x7f) << 24