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

摘要

A data search server 300 stores a system ciphertext 230 including a data ciphertext and a keyword ciphertext in each category-specific DB unit 391 for each data category, and stores each category-determination secret key 153 being associated with each category-specific DB unit 391. A search request receiving unit 331 receives from a data search terminal a search request including a search trapdoor and an index tag. A data searching unit 332 searches for a category-determination secret key 153 with which the index tag is decrypted to the same value as a key-determination value 191. Using the search trapdoor, the data searching unit 332 performs a search of a Public-key Encryption with Keyword Search scheme on system ciphertexts 230 in a category-specific DB unit 391 associated with this category-determination secret key 153. A search result transmitting unit 333 transmits to the data search terminal 100 a data ciphertext included in a system ciphertext 230 which has been found as a hit in the search.