DATA SEARCH DEVICE, DATA SEARCH METHOD, DATA SEARCH PROGRAM, DATA REGISTRATION DEVICE, DATA REGISTRATION METHOD, DATA REGISTRATION PROGRAM AND INFORMATION PROCESSING DEVICE

摘要

This data search server (300) stores system cipher-text units (230), which include a data cipher-text unit and a keyword cipher-text unit, by category of data in a per-category database unit (391) and stores category assessment-use secret keys (153) which have been associated with the per-category database units (391). A search request reception unit (331) receives a search request, which includes a search-use trapdoor and an index-use tag, from a data search terminal. A data search unit (332) retrieves a category assessment-use secret key (153) which decrypts the index-use tag to the same value as a key assessment value (191) in order to retrieve the system cipher-text unit (230) within the per-category database unit (391) corresponding to the category assessment-use secret key (153) of the same using the search-use trapdoor with a searchable public key encryption method. A search result transmission unit (333) transmits the data cipher-text unit included in the system cipher-text unit (230) that has matched the search to a data search terminal (100).