Patent ID: 8195936

Claim:
A communication terminal comprising: a rolling token generation unit for generating rolling tokens; a memory for storing the generated rolling tokens; and a control unit for controlling the rolling token generation unit to, when an authentication of another terminal for performing a communication is completed, generate and transmit a first rolling token to the another terminal, for, when receiving a second rolling token and a third rolling token from the another terminal, determining whether the second rolling token currently received from the another terminal is identical to the first rolling token, and for, when the second rolling token is identical to the first rolling token, controlling the rolling token generation unit to generate a fourth rolling token and transmit the third rolling token and the fourth rolling token to the another terminal, and wherein when a plurality of rolling tokens transmitted is received within a specified time, the control unit requests authentication information from the another terminal, receives the requested authentication information from the another terminal, and performs the authentication of the another terminal.