Research On Sorting Supported,Backward And Forward Secure Dynamic Symmetric Searchable Encryption

Our life has become convenient in the information age.E-wallets,e-stores,e-medicine are becoming more common.With the application of big data,every trace of our daily life is recorded.However,the more detailed electronic records of people's privacy,the more likely it is to be leaked,which causes troubles to our life somehow.At present,most cus-tomers' data is stored in the cloud server,so the data security of the cloud environment has attracted more attention.In relation to it,the search technology and update technology under the condition of encryption are also becoming very popular.Symmetric searchable encryption technology has been explored by many researchers because of its support for searching on encrypted data and its high efficiency and wide ap-plication prospects.There is a lot of space for optimization in the terms of update function,security and efficiency of the symmetric searchable encryption technology.At present,there is little research on forward and backward secrecy dynamic searchable encryption schemes in a multi-user environment.And most of them only consider forward secrecy.In the existing schemes,adversaries can undermine the forward secrecy of the scheme through eavesdropping attacks and replay attacks.What's more,due to most solutions lack the consideration of the backward secrecy,the server can easily search for deleted data.Based on the previous scheme,this thesis introduces an incremental puncturable en-cryption technology to reduce the search ability of server for deleted data,which strengthen both the backward secrecy and the forward secrecy.Double-chain index form is intro-duced to ensure that the efficiency of search will not be affected.At the same time,the introduction of the sorting function enables the search to be better realized in accuracy.The main contributions of this thesis include the following aspects:· Data sorting algorithm Aiming at the problem of search efficiency,we have introduced the TF-IDF weighting algorithm to obtain the importance of the data for keywords.By mapping and hiding the specific links of keywords,our method can improve the accuracy of retrieval and guarantee the security of search.At the same time,it can optimize the index structure to improve the efficiency of search operation.· Forward Security By introducing the state chain index to ensure that users cannot deduce the keyword information corresponding to the previous data through the newly added data,and to guarantee that using the old search token,it cannot act on the newly added index item,but the new token can retrieve the latest data.· Backward security Puncturable encryption algorithm is a common method of backward security.In this thesis,we improve the incremental symmetric punc-turable encryption algorithm to ensure backward security,so that the server cannot decrypt and retrieve the punctured index.Benefit from this algorithm,we can re-voke the server's ability to search for deleted data.· Multi-user query The use of enhanced multi-user registration processing and dy-namic search tokens make it impossible for adversaries to obtain encrypted infor-mation through forged tokens.The realization of a multi-user query mechanism also greatly improves data availability of data and sharing of resource.