Patent ID: 7302252

Claim:
An authentication system comprising: a wireless communication terminal; a base station for establishing wireless communication with the wireless communication terminal; and an administration server for managing communication between the wireless communication terminal and the base station, wherein the wireless communication terminal comprises a terminal side receiver transmitter module for exchanging information with the base station, a terminal side authentication module for performing an authentication process in relation to the base station and a terminal side recording module for recording digital coupons each of which includes a public part of coupon and a secret part of coupon; wherein the base station comprises a base station side receiver transmitter module for exchanging information with the wireless communication terminal, a base station side recording module and a base station side authentication module for performing an authentication process in relation to the wireless communication terminal; wherein the administration server generates a random number (s) as a terminal secret key (s) and calculates a value (v=g −s mod p) as a terminal public key (v), where the values q, p are parameters for coupon generation; wherein the administration server generates a random number (x) as the secret part of coupon (x) and calculates a value (t=g x mod p) as the public part of coupon (t); wherein the administration server transmits the terminal public key (v) to the base station and the terminal secret key (s) and the digital coupons to the wireless communication terminal; wherein the base station side recording module records the terminal public key (v); wherein the terminal side recording module records a plurality of pieces of digital coupons and the terminal secret key (s); wherein the terminal side receiver transmitter module transmits one of the plurality of pieces of digital coupons to the base station and then invalidates the transmitted digital coupon; wherein the terminal side receiver transmitter module transmits a connection request containing an identifier of the terminal secret key (s) and the public part of coupon (t) to the base station; wherein the base station side authentication module generates a random number (c) upon reception of the connection request and transmits the generated random number (c) to the wireless communication terminal; wherein the terminal side authentication module calculates a response (y=x+sc) in accordance with the received random number (c), the secret part of coupon (x) and the terminal secret key (s), and then transmits the response (y) to the base station; and wherein the base station side authentication module authenticates the wireless communication terminal by calculating a value (g y v c mod p) based on the received response (y), the random number (c) and the terminal public key (v) and judging whether the obtained calculation result agrees with the public part of coupons (f).