Abstract: A unique identifier is assigned to each user, and a standard for evaluating the reliability of information dispatched on the Internet using the identifier to reveal the source of the information is achieved by: using the identifier as a search term, and acquiring a corresponding public key from information publicly available on the Internet; using the public key to verify a signature added to text information that includes the identifier; and confirming whether the source of the text information links back to the public key and the identifier. Thereby, an equivalence relation on the text information is established on the basis of the public key and identifier.

Abstract: A method of providing a service from a service provider to users is described. The method comprises: a step of generating an electronic signature on a first information provided by a user with a secret key of the service provider and providing the electronic signature to the user, a step of receiving a request for the service together with information identifying the first information item from a user and accepting this request if it is justifiable; a step of receiving, if the request is accepted, a second information item from the user; a step of determining whether or not there is a predetermined relationship between the first information item and the second information item; and a step of performing, if there is the predetermined relationship, a necessary procedure for providing the service by the use of an information processing device; and a step of saving the second information item even after providing the service as an evidence that the service has been provided.

Abstract: An improved optical memory disc is disclosed which has a liquid crystal layer on which information is written by applying electric field. The liquid crystal layer is sectioned into a plurality of concentric tracks by concentric grooves. When information is written or read, an auto-tracking method can implemented by aid of the grooves.