AUTHENTICATION SYSTEM, INFORMATION REGISTRATION SYSTEM, SERVER, PROGRAM, AND AUTHENTICATION METHOD

摘要

This authentication system (1) includes a user terminal (10) and a server (11) that can communicate with the user terminal (10). The user terminal (10) transmits the following to the server (11): the authentication ID of the user terminal (10), a first inputted code, and a second code encrypted using the first code. The server (11) decrypts the encrypted second code using the first code, and authenticates the user terminal (10) using the decrypted second code and the authentication ID of the user terminal (10). The first code contains a smaller amount of data than the second code.