Abstract: Aiming at the safety problem of outsourcing data to cloud servers for mobile cloud environment,in order to ensure the safety of data and the efficiency of ciphertext retrieval,by improving the traditional ciphertext retrieval system structure,a private cloud index file server is introduced for separating the index file and ciphertext file.Based on this,a privacy-preserving oriented ciphertext retrieval algorithm was proposed.Considering the weak computing ability of mobile devices,to reduce the computational overhead,a symmetrical searchable encryption scheme is adopted.Furthermore,an index structure based on trie tree was proposed to improve the efficiency of retrieval,and support retrieve for result.The theoretical analysis and experimental results show that the proposed scheme can achieve the privacy guarantee,and has a good performance on the stored space and retrieval time.

Key words: Cloud computing,Ciphertext retrieval,Privacy-preserving,Searchable encryption,Trie