RETRIEVAL SYSTEM, RETRIEVAL DEVICE AND RETRIEVAL METHOD

A retrieval system includes a first management unit which stores, in a first storage area that cannot be browsed by an administrator of a provider machine, management information in which an encrypted retrieval keyword used for a retrieval performed by the provider machine, and an encrypted ID, which is associated with the encrypted retrieval keyword, are associated, and, of the management information, decrypts, and then once again encrypts, the encrypted retrieval keyword corresponding to the encrypted query from a browsing machine and the encrypted ID corresponding to the encrypted retrieval keyword, and a second management unit which stores, in a second storage area, index information in which the encrypted retrieval keyword used for the retrieval performed by the provider machine, and one or more encrypted IDs associated with the encrypted retrieval keyword, are associated, and, of the index information, updates the encrypted retrieval keyword and the encrypted ID corresponding to the encrypted query from the browsing machine to the encrypted retrieval keyword and the encrypted ID which were decrypted and then encrypted by the first management unit.