Research On Dynamic Searchable Encryption Based On Mail System

The rapid development of cloud computing has had a profound impact on both industry and academia.Cloud servers have powerful computing ability and massive storage space,so they can help users perform the complex processing of large amounts of data and improve efficiency greatly.At the same time,the reliability and security of cloud computing servers have aroused extensive attention.Semi-trusted cloud servers can easily obtain users' data,while service providers are likely to sell users' private data for extra profit.To ensure security,data should be encrypted before being uploaded.Therefore,how to deal with encrypted data has become a new challenge.It should be noticed that search is an important topic of data processing.So the researches of searchable encryption apperaed.This paper studies searchable encryption as follows:1.We propose a secure dynamic public key searchable encryption scheme(SDKSE)for mail systems that supports updating keywords and files.The receiver builds a binary tree to manage all the keywords in the system,and constructs encryption and decryption algorithm according to their locations in the tree.The indexes and trapdoors generated in the scheme are constant size.And our scehme has both index indistinguishable security and trapdoor indistinguishable security.2.On the basis of the previous scheme,we try to improve the security and construct a secure dynamic keyword searchable encryption scheme which can resist keyword guessing attack(SDKSE-KGA).This scheme can retain the original function of dynamic management of keywords and files.It designs the fuzzy mapping algorithm based on the properties of the binary tree.In this algorithm,fuzzy keywords can confuse exact keywords so that keyword guessing attack can not be established.The search algorithm is completed by both the cloud server and the receiver,so that the semi-trusted cloud server can not get other useful information except fuzzy trapdoors.3.To implement a new functionality,we construct a secure dynamic keyword searchable encryption scheme with fuzzy keyword search(SDKSE-FKS).We assign actual meaning to each keyword in the binary tree and design an appropriate algorithm to achieve fuzzy keyword search.In this algorithm,it chooses one fuzzy keyword to represent a set of synonyms.When the cloud server searches for this fuzzy keyword,it will get all the files containing this term and its synonyms.