code: function compareHmac(hmac1, hmac2) {
      var left = hmac1;
      if (Buffer.isBuffer(hmac1)) {
          left = hmac1.toString('base64');
      }
      var right = hmac2;
      if (Buffer.isBuffer(hmac2)) {
          right = hmac2.toString('base64');
      }
      return (left == right);
  }
docs: Compare HMACs
  @param {String|Buffer} hmac1
  @param {String|Buffer} hmac2
  @returns {Boolean}