SDK02-2, a time-based token,enables strong authentication by positively identifying user with one-time passwords. Based on the background algorithm, this token automatically generates a one-time password sequence. By identifying users without device connection, SDK02 enable user access with zero-footprint. SDK02-2 provides the most easy-to-use and cost-effective two-factor authentication for enterprises to manage user accessing, gives strong protection to sensitive information, internet-based business activities and online transactions.