Information processing system, one or more non-transitory computer-readable storage media having program stored therein, and authentication method

Abstract

A server issues challenge data and transmits the challenge data to a client. The client stores encrypted group data including a plurality of encrypted data encrypted with a server key, and parameter data A, in a memory, receives the challenge data, generates response data using a response key on the client side, and transmits the response data, the encrypted group data, and the parameter data A to the server. The server selects encrypted data to be used from the received encrypted group data, based on the received parameter data A, sets a response key on the server side, based on the selected encrypted data and data decrypted with the server key, verifies the received response data, based on the challenge data and the response key on the server side, and notifies a result of the verification to the client. The client receives the notification.