The Design And Implement Of A Multi Keyword Searchable Encryption Scheme Supporting Boolean Query

Information security is always one of the most important problem in computer communication.With the development of the Internet technology and the arrival of the big data era,people pay much more attention to information security.It's not only necessary to protect the security of the data,but also to protect users' privacy.There are many ways to protect the security of data.Cryptography,among all kinds of approaches,is the relatively easy and important one.It can hide the plaintext from adversary by simply encrypting.Especially in nowadays,cloud technology and cloud storage develop quickly.More and more people choose to put their data to the remote server,because of its convenience,to save storage space.However it's right because the data is out of the control of the owner,the server,honest but curious and other adversary can attack the cloud server,lead to the leakage of data.Sometimes it is more seriously,the data is altered.To prevent data from rewriting and protect the privacy of users,people choose to encrypt the message than put the cipher to the server.Server has no key and can't decrypt the cipher.Although the problem before is addressed,other question appears.That is with the increase of cipher,it becomes impossible when user want to search for documents contained certain keywords.Because the server can't do any operation on cipher.To deal with this situation,searchable encryption was proposed in 1996 for the first time.Then develop rapidly in a short time.From the symmetric searchable encryption schemes to the asymmetric searchable encryption schemes,more and more searchable encryption algorithms are proposed.At the beginning,the symmetric searchable schemes only suit for the situation that single user writes and single user reads,which is impracticable.With the development of Diffie-Hellman protocol and public key cryptography,there are also public key based searchable encryption scheme arisen,which can be used in the situations like multi users write and single user reads,single user writes and multi users read,even the multi users write and multi users read model,though it is rare.Besides application model,search efficiency is another significant problem of searchable encryption.Among current schemes,the search efficiency is relative with the total keyword ciphers,which is not enough at the big data era.Therefore,this paper is going to design and achieve an efficient multi keyword searchable encryption scheme,which can use for the model that multi users write and single user reads.The scheme we proposed has three character.One is we uses a star-like structure to store the keyword cipher,which connects the same word,but the relation is hided from anyone who does not have the trapdoor.The subtle design of this structure reduces the search time a lot,relevant to the number of search keyword,rather than the whole keyword number.Another character is that we built connection between keywords to fulfill the function of multi keyword search,which can reduce the leakage of information caused by simply searching for every word and gathering the intersection part.The last one is that among all the keywords,you can search the files contain all of them by using the Boolean operation AND,or search the files contain some of them by using the Boolean operation OR.At the last of this paper,we test our scheme by many experiments.