부산대학교 도서관

A method includes encrypting a request received from a user device to generate an encrypted request. Encrypted data items are searched based on the encrypted request to identify desired encrypted data items. In response to determining that two or more encrypted data items of the desired encrypted data items have a same interaction identification, the two or more encrypted data items are locked and masked, and the masked two or more encrypted data items are removed. Algebraic operations are determined based on the encrypted request. An encrypted response is determined by performing the algebraic operations on the desired encrypted data items. The encrypted response is decrypted to obtain a decrypted response. An error is determined due to the algebraic operations performed on the desired encrypted data items. In response to determining that the error is less than an error threshold, the decrypted response is sent to the user device.