Patent ID: 7801915

Claim:
A method of managing confidentiality of user information by use of an apparatus which manages confidentiality of the user information, wherein the apparatus includes a recording unit operable to record information in association with any one of a history of users having accessed the user information, and access rights defining users authorized to access the user information, the method comprising the steps of: recording user information, the user information containing a plurality of information items, in association with any one of a history of users having accessed the user information, and access rights defining users authorized to access the user information; receiving management information, the management information indicating whether the user information should be managed confidentially, in association with a plurality of hash values of the user information, each of the received plurality of hash values corresponding to a respective information item contained in the user information; comparing hash values of the recorded user information with the received hash values in response to receipt of management information of the user information, wherein comparing hash values further comprises calculating hash values for each of the information items of the recorded user information and comparing the respective calculated hash values with the respective received hash values for each information item; generating management information indicating whether the user information should be managed confidentially from a certain user, based on the received management information, on condition that, with respect to a predetermined criteria number or more of the information items, the compared hash values coincide with each other; selecting users able to access the user information, based on any one of the history and the access rights recorded in the recording unit; notifying the selected users of the generated management information in association with identification information of the user information, in order to cause the user information to be managed by the selected users in accordance with the generated management information; and changing the predetermined criteria number in response to instructions of users.