Research On Fuzzy Retrieval Over Cipher Text Based On Chinese Keyword

In the era of rapid development of information and network,the global information is developing to the network,which makes the data sharing and communication among users becoming more real-time and convenient.At the same time with the expansion,development and change in the field of industry,more and more data is growing exponentially.The Traditional way of data storage and use have been unable to satisfy the needs of users.More and more data is transported to the cloud,but as we know the cloud servers and users are in different trusted domains,that exists certain risks.In order to protect the user's data,generally we always encrypt the data before uploading to the cloud servers.The data stored in the cloud servers is encrypted,so it can prevent the sensitive information not to be leaked and resist the attack by malicious attackers.Although the cloud server has a huge storage space and a strong operation ability,and it can realize a fast data retrieval,but the research of efficient cipher text retrieval is still a research hotspot.The method of traditional cipher text retrieval is realized by using the keywords to accurately match,so it has no fault tolerance,when users input errors result in incorrect output.However,in the actual process of retrieval,the user may enter a wrong retrieval requests,under this how to ensure the retrieval efficiently,and also improve the recall ratio and the precision of the retrieval is one of the cipher text fuzzy retrieval research direction.The purpose of this thesis is to solve the cipher text retrieval based on fuzzy keyword in Chinese environment.First of all,the thesis analyzes the problems when using the existing fuzzy set method construction to build the Chinese keyword fuzzy sets.Combining with the figural ideographic characteristics of Chinese characters,then proposed a method which is based on the keyword in Chinese pinyin and nearly shaped word to build the keyword's fuzzy sets.So that can improve the rate of fault tolerance of the fuzzy sets.Then by analyzing the traditional expressly inverted index structure,combined with the improved keyword weight calculation method,we design an index structure which can resist the semantic analysis.At the same time,when encrypting the index,we use an ordered preserving encryption methods,both can resist statistical analysis and also can improve the retrieval accuracy.Secondly,by studying the cipher text fuzzy retrieval scheme,in the thesis gives the corresponding encryption mechanism and key management method which is based on the proposed index structure,gives.Using multiple tree realize the index and cipher text retrieval,the sequence in the same node with the same prefix,which narrows the storage of the index at the same time improve the retrieval performance.The process of ordering the result,combined with word's fuzzy degree and weights.Finally,according to the fuzzy sets of the keywords and the cipher text fuzzy retrieval method,designs a system which support cipher text retrieval based on fuzzy Chinese keyword.Then analyze the retrieval efficiency and performance of the system.And by testing an experiment under this system,analyzing the size and the constructed time of the fuzzy sets and the indexes.