SECRET RETRIEVAL SYSTEM, PUBLIC PARAMETER GENERATION DEVICE, ENCRYPTION DEVICE, USER SECRET KEY GENERATION DEVICE, QUERY ISSUE DEVICE, RETRIEVAL DEVICE, COMPUTER PROGRAM, SECRET RETRIEVAL METHOD, PUBLIC PARAMETER GENERATION METHOD, ENCRYPTION METHOD, USER SECRET KEY GENERATION METHOD, QUERY ISSUE METHOD, AND RETRIEVAL METHOD

摘要

In a secure search system to be used by a plurality of users, the size of a ciphertext is reduced and the need to generate a new ciphertext when a new user is added is eliminated. A public parameter generation device 100 generates a pair of a public parameter and a master secret key. Using the public parameter, an encryption device 400 encrypts a keyword and generates a ciphertext. Using the master secret key, a user secret key generation device 200 generates a user secret key of a query issuing device 300. Using the user secret key, the query issuing device 300 generates a query for searching for the keyword. Based on the ciphertext and the query, a search device 500 determines whether a hit is obtained for searching.