Fuzzy Keyword Searchable Encryption Algorithm Research And Implementation

With the development of Cloud Computing Technology, large numbers of users are desirable to outsource their data to the cloud. Once the private data is outsourced, users may worry about the data security. Therefore, in order to ensure the outsourced data confidentiality, users should encrypt their private data before outsourcing their data.However, it causes the problem how to search for encryption data efficiently. To solve it,Scholars proposed the notion of searchable encryption.Fuzzy Keyword Searchable encryption is an important solution supporting searchable encrypted data. This thesis mainly makes researches on efficient Fuzzy Keyword searchable encryption schemes in two scenarios with a semi-honest server and hybrid cloud multi-user respectively. For the scenario with a semi-honest server, this thesis puts forward an efficient algorithm which can verify the results from the server.And for the scenario with multiple users in a hybrid cloud, this thesis constructs another algorithm which can dynamically update user privilege. The achievements of this thesis are shown as follows:1. This thesis proposes a new data structure of attribute symbol tree and further proposes an efficient verifiable dictionary fuzzy keyword searchable encryption scheme with the symbol tree structure on the encrypted data. In the proposed scheme, a verification structure based on attribute symbol index tree is established so that it achieves data search on ciphertexts and supports searching results verification in a semi-honest server scenario. Compared with other verifiable and searchable encryption schemes, verifying computation cost of the scheme can be reduced to O(1). And the proposed scheme is comparable to the existing optimal fuzzy keyword search encryption scheme in the term of the query cost.2. This thesis proposes an efficient fuzzy keyword searchable encryption scheme with multi-user privileges dynamic revocation in a hybrid cloud. In the hybrid cloud scenario, the public server is semi-honest-but-curious and the private server is honest-but-curious. In the proposed scheme, it exists a key management mechanism which is set up based on broadcast encryption and a multi-user access control mechanism. With these two mechanisms, the proposed scheme can achieve authorized users adding and revocation dynamically without impacting on other users in a certaingroup. Compared with other schemes supporting multi-user revocation, the storage overhead of the proposed scheme can be reduced to O(1). In addition, it is provable that the proposed scheme protects the data privacy from data exposure caused by multiple users.In the end, this thesis makes performance comparisons and analyses. The results demonstrate that the two schemes proposed in this thesis are both efficient and practical.