Abstract: An information terminal of a user B who permits a user A to search the person B calculates a calculation result G(Pa?, Pb) by using information Pa? related to the user A and information Pb of the user B, both Pa? and Pb being stored in the information terminal of the user B and transmits to a server the calculation result G(Pa?, Pb). Further, the information terminal of the user B receives trust information expressing that Pb is authenticated and calculates a calculation result F(Pb) and transmits to the server. The information terminal of the user A calculates G(Pa, Pb?) and transmits it to the server. When the server receives G(Pa, Pb?) from the information terminal of the user A, the server searches G(Pa?, Pb) which matches G(Pa, Pb?) and the search result with F(Pb) to the information terminal of the user A. The information terminal of the user A calculates F(Pb?) and compares it with F(Pb) which is sent by the server.

Abstract: A technique for synchronization of the information on multiple information terminal devices is disclosed. The information to be stored is stored in encrypted format in a server unit, and thus the server unit administrator cannot access this information. In the information terminal device where information is to be synchronized, encrypted changed information, where difference information or any set of difference information generated due to changes in the information, is encrypted, and is sent to the server unit. Then the server unit stores this encrypted changed information by correlating a revision number with it. A terminal device receives the revision number correlated with the encrypted changed information, and stores it by correlating it with the difference information or any set of difference information.

Abstract: An embodiment of the present invention provides an information exchange device. The information exchange device includes a storage device which stores information items for disclosure, an encryption device which encrypts each of the information items for disclosure using a plurality of prepared secret keys which correspond to each of the information items for disclosure, a transmitting device which transmits the encrypted information items and the plurality of prepared secret keys, and a decryption device which receives an encrypted information item which is arbitrarily selected from the plurality of encrypted information items, receives a secret key related to the selected encrypted information item from among the plurality of prepared secret keys, and decrypts the selected encrypted information item using the secret key.

Abstract: A system includes an information terminal of a user B which stores information of users A and B; an information terminal of a user C which stores information of users A and B; and a server. The information terminal of the user B generates a first calculation result by an arbitrary calculation of the information stored therein and sends this result to the server to be registered. The server correlates an identification tag of the user B with the first calculation result and stores this information. The information terminal of user C generates a second calculation result by the arbitrary calculation of information stored therein and sends this result to the server to be registered. The server correlates an identification tag of the user C with the second calculation result and stores this information.

Abstract: One embodiment of the present invention provides an information terminal that includes: a first receiver for receiving trust information from a trust information provider, the trust information including identification information of a terminal belonging to an authenticatee and showing that the terminal belonging to the authenticatee is authenticated by the trust information provider; a storage device for storing the trust information; a second receiver for receiving an identification tag of the terminal belonging to the authenticatee from a server; and an outputting device for outputting information for performing an identification judgment of the terminal belonging to the authenticatee based on the identification tag of the terminal belonging to the authenticatee and the trust information stored in the storage device.

Abstract: A database system that includes a database for storing one or a plurality of relationships existing between a plurality of first instances belonging to a first entity and a plurality of second instances belonging to a second entity. A microprocessor is provided for searching the database when one or more of the first instances are selected as a first selected set for determining a first relationship existing between an instance in the first selected set and one of the plurality of the second instances, and when one or more of the second instances are selected as a second selected set for determining a second relationship existing between one of the plurality of first instances and a instance in the second selected set.

Abstract: A system having a server and an information terminal of A which records A's personal information Pa and B's personal information Pb?, an information terminal of B which records A's personal information Pa and B's personal information Pb?. B's information terminal generates a calculation result F(Pa?,Pb) via the calculation of Pa? and Pb, sends F(Pa?,Pb) to a server. The server correlates B's identification tag with F(Pa?,Pb) and records it. A's information terminal forms F(Pa,Pb?) calculated via the calculation of Pb? and Pa and sends F(Pa,Pb?) to the server. The server searches for a calculation result which matches F(Pa,Pb?) and by detecting a match between F(Pa?,Pb) and F(Pa,Pb?) detects B's identification tag which has been correlated with F(Pa?,Pb) and detected B's identification tag is sent to A's information terminal.

Abstract: An information terminal that includes a receiver for receiving an identification tag, with the identification tag having a plurality of sets of information including first information and attribute information which is correlated with the first information, a storage device for storing the identification tag and the plurality of information sets and a display, with the display displaying the first information, and the first information being correlated with the attribute information based on the attribute information which is selected by a user from the plurality of sets of information.

Abstract: An information terminal includes a microprocessor for gathering a plurality of information sets of a user, with the user being a communication partner, and the information set including an identification tag for specifying the communication partner, communication service information corresponding to a specific communication service among a plurality of communication services and contact information of the communication partner, and a storage device for storing the plurality of information sets.