Patent ID: 8522331

Claim:
A non-transitory computer readable storage medium storing a program causing a computer to execute a process for authenticating a user in a site included in an authentication system in which a plurality of sites are linked to each other, the process comprising: receiving authentication information; authenticating the user in a first site of the authentication system based on the received authentication information; receiving a suspicious behavior notification including suspicious behavior information which denotes that suspicious behavior of the user has been detected; registering the received suspicious behavior information; determining a reliability level among reliability levels of the user as a function of the registered suspicious behavior information, the reliability level indicating a degree among various degrees of reliability; in response to the user accessing a second site of the authentication system, adding the reliability level of the user determined in the determining of the reliability level to the authentication information received in the authenticating of the user, and transmitting the authentication information to which the reliability level is added to the second site; and determining a function to be provided to the user in the first site based on the reliability level of the user by providing a first function based on the reliability of the user and not providing a second function based on the reliability level of the user.