A retrieval system comprising a provider machine which performs a retrieval in response to an encrypted query as an encrypted version of a query from a browsing machine for browsing encrypted data as an encrypted version of data, and provides a retrieval result to the browsing machine , the retrieval system comprising: a first management unit which stores, in a first storage area that cannot be browsed by an administrator of the provider machine by utilizing a Trusted Execution Environment, TEE, function, management information in which an encrypted retrieval keyword as an encrypted version of a retrieval keyword used for the retrieval performed by the provider machine , and an encrypted ID, which is associated with the encrypted retrieval keyword, as an encrypted version of identifying information capable of identifying the encrypted data, are associated, and wherein the first management unit decrypts, and then once again encrypts, the encrypted retrieval keyword corresponding to the encrypted query from the browsing machine and the encrypted ID corresponding to the encrypted retrieval keyword from the management information ; 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 wherein the second management unit updates the encrypted retrieval keyword and the encrypted ID corresponding to the encrypted query from the browsing machine in the index information to the encrypted retrieval keyword and the encrypted ID which were decrypted and then encrypted by the first management unit , wherein encryption is performed using a probabilistic method, wherein the value of the encrypted data after being re-encrypted is different from the previous value. a first management unit which stores, in a first storage area that cannot be browsed by an administrator of the provider machine by utilizing a Trusted Execution Environment, TEE, function, management information in which an encrypted retrieval keyword as an encrypted version of a retrieval keyword used for the retrieval performed by the provider machine , and an encrypted ID, which is associated with the encrypted retrieval keyword, as an encrypted version of identifying information capable of identifying the encrypted data, are associated, and wherein the first management unit decrypts, and then once again encrypts, the encrypted retrieval keyword corresponding to the encrypted query from the browsing machine and the encrypted ID corresponding to the encrypted retrieval keyword from the management information ; 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 wherein the second management unit updates the encrypted retrieval keyword and the encrypted ID corresponding to the encrypted query from the browsing machine in the index information to the encrypted retrieval keyword and the encrypted ID which were decrypted and then encrypted by the first management unit , wherein encryption is performed using a probabilistic method, wherein the value of the encrypted data after being re-encrypted is different from the previous value. <EOS>