Abstract: A security key including an interface unit that provides an interface with an authentication device installed at a security domain; and an OTP module that communicates with the authentication device through the interface unit mentioned above, wherein the OTP module includes a storage unit that stores at least one OTP Seed ID and OTP Algorithm ID; and an OTP generation unit that generates an OTP by using an OTP Seed value and OTP algorithm that are identified by an OTP Seed ID and an OTP Algorithm ID matching with the OTP Seed ID and OTP Algorithm ID included in the OTP request message, which is received from the authentication device among the OTP Seed ID and OTP Algorithm ID stored in the storage unit, and provides the authentication device with the OTP generated in the process.