Research On Fuzzy Keyword Search Method Of Encrypted Data In Cloud Computing

With the rapid development of cloud computing in academia and industry, more and more sensitive information are being centralized into the cloud, such as emails, personal health records, government documents, etc. By storing their data into the cloud, User can access to achieve maximum efficiency and minimal management overhead, the data owners can be relieved from the burden of data storage and maintenance so as to enjoy the on-demand high quality data storage service. However, the fact that data owners and cloud server are not in the same trusted domain may put the outsourced data at risk, as the cloud server may no longer be fully trusted. Because of the cloud server in the process of running may reveal some information to unauthorized users. It follows that sensitive data usually should be encrypted prior to outsourcing for data privacy and combating unsolicited accesses. However, data encryption makes effective data utilization a very challenging task given that there could be a large amount of outsourced data files. Moreover, in Cloud Computing, data owners may share their outsourced data with a large number of users. The individual users might want to only retrieve certain specific data files they are interested in during a given session. One of the most popular ways is to selectively retrieve files through keyword-based search instead of retrieving all the encrypted files back which is completely impractical in cloud computing scenarios. Such keyword-based search technique allows users to selectively retrieve files of interest and has been widely applied in plaintext search scenarios, such as Google search.Unfortunately, data encryption restricts user’s ability to perform keyword search and thus makes the traditional plaintext search methods unsuitable for Cloud Computing.Besides this, data encryption also demands the protection of keyword privacy since keywords usually contain important information related to the data files. Although encryption of keywords can protect keyword privacy, it further renders the traditional plaintext search techniques useless in this scenario.The existing solutions can be divided into two categories:Searching on Exact Keywords and Searching on Fuzzy Keywords. Traditional searchable encryption scheme only support exact keyword search, efficiency and performance can’t adapt to the cloud computing environment, fuzzy keyword search allows the user to search some approximation of the encrypted data keywords, this scheme is suitable for the inexact match the search keyword set. To securely search over encrypted data, searchable encryption techniques have been developed in recent years. Searchable encryption schemes usually build up an index for each keyword of interest and associate the index with the files that contain the keyword. By integrating the trapdoors of keywords within the index information, effective keyword search can be realized while both file content and keyword privacy are well-preserved. This thesis launches the research from the following several aspects:Firstly introduces the basic concept of public-key encryption with keywords search,starting from the definition of public-key encryption with keywords search introduce public-key encryption model,to introduce the public-key encryption keywords search contains the identity-based encryption.Then can search the structure of the encryption scheme is given, from the concept of bilinear mapping, the concept of security that provable,random oracle model and the security of public-key encryption to introduce the structure of the concrete scheme public-key encryption with keywords search, the final analysis is carried out for the security of the scheme.Second is put forward to support multiple string similarity operation index R+tree to be constructed,implementation of encrypted data fuzzy keyword search in cloud computing, using edit distance to quantify the similarity of the keyword, puts forward a can return with keyword is closer to the document retrieval method.Through the string clustering to improve the efficiency of fuzzy keyword search.Using Fuzzy extractors build a concrete scheme, realize the fuzzy keywords search.And in a Well-safety define resistance of adaptive adversary attack.The scheme also Suitable to other similar measures, such as hamming distance, edit distance, set difference.etc.This scheme does not require users to build and store anything in advance, only need to use the secret key to encrypt data and calculated the trapdoor keywords document.The index table consists of the random strings extracted from a fuzzy extractor. So, by the fuzzy extractor, we transform the servers’ searching for Fuzzy keywords on ciphertexts to the searching for exact keywords on plaintexts.