Abstract: Dynamic searchable symmetric encryption(DSSE) technology,as an extension of static searchable encryption,has attracted much attention because it solves the problem of secure retrieval over encrypted data and supports data dynamicity.For practicality concerns,most current DSSE schemes leak extra information(e.g.,search patterns and access patterns) to fast search.Recent studies show that this leaked information poses serious security problems,the adversary with background know-ledge of the database may exploit the leaked information to recover the query or reconstruct the database.Since this information reveals along with the query process,scholars propose to refresh the encrypted database after the query to reduce the above potential risks.However,this approach leads to huge client-side communication,storage,and computation overheads.Because the client needs to download the results locally,decrypt them,re-encrypt them and finally upload them to the cloud.To address this problem,this paper proposes a new updatable DSSE scheme that hides all the above information including access pattern,search pattern.The scheme can update data directly at the server side without disclosing data privacy,thus reducing the communication overhead of traditional update methods of the client side.The security analysis shows that this scheme can hide the search pattern effectively.In addition,the communication cost of the proposed scheme is also significantly degraded when compared with the traditional scheme that executes ciphertext refreshing by the client.For example,in the case of keywords matching 100 documents,compared with downloading to local re-encryption and retransmission,the communication overhead of this scheme is reduced by 70.92%.

Key words: Dynamic searchable encryption, Updatable encryption, Forward secure, Search pattern