Patent ID: 8914643

Claim:
An anonymous authentication system comprising a group management device for managing a group of users, an authentication-subjected user device for requesting verification as to whether or not a user who is to be authenticated belongs to the group, in accordance with the user's operation, a verification device for receiving the verification request and for verifying that the user who is to be authenticated and who has requested the authentication belongs to the group, a verification assistant device for assisting in the verifying operation, and an authentication-subjected user identification device for identifying the user who is to be authenticated, wherein: said authentication-subjected user device generates unlinkable authentication data from open information of the group to which the user to be authenticated belongs, open information and secret information which are unique to the user to be authenticated, and an information nonce which is generated at each authentication, said verification assistant device extracts information regarding the open information and public information which are unique to the user from said unlinkable authentication data using secret information which corresponds to the open information of said group, authenticates, from the extracted information regarding the open information and public information which are unique to the user and from a list of user's open information which is managed by the group, that the user who belongs to the group has generated said unlinkable authentication data, and generates authentication assistant data including the result of the authentication, said verification device receives said unlinkable authentication data from said authentication-subjected user device, transmits said unlinkable authentication data to said verification assistant device, receives from said verification assistant device verification assist data for said transmitted unlinkable authentication data, verifies using said verification assist data that the user to be authenticated belongs to the group, and generates from the result the verification result as to whether or not the user who is to be authenticated belongs to the group, said authentication-subjected user identification device identifies the user who is to be authenticated and who corresponds to said unlinkable authentication data from said unlinkable authentication data, the secret key of the group and the list of user's open information which is managed by the group, wherein said verification device carries out an anonymous authentication of the user who is to be authenticated based on an identification of the user by the verification assistant device.