“…We can use any block cipher technique such as AES, RSA, Blowfish, etc., with the key size 128 bits. If there is unique user (also the data owner) in the system, we use one key for encrypting the whole database; otherwise, we use multiple keys which are managed by a key management mechanism [8,9,10]. The index is created based on the mapping function Map R.Ai (v), which will be defined as the following: We use the operator D that maps the encrypted representation to its corresponding unencrypted representation.…”