Research On The Publicly Verifiable Conjunctive Keyword Search In Cloud Computing

Cloud computing,the new term for the long dreamed vision of computing as an infrastructure,is a dynamic scalable computation paradigm.The rapid development of cloud computing makes the storage outsourcing become an attractive trend.By outsourcing the mass data to the cloud server,consumers can not only enjoy the high quality of data storage services,but also reduce the costs of the local data management and the hardware maintenance.However,once the data are outsourced to the cloud server,the separation of ownership and management of the data makes the privacy and security of the outsourced data more serious.To reduce the risk of leaking sensitive data,the data should be encrypted before outsouring,but this will raise a challenge for performing search over the encrypted data efficiently.Searchable encryption technique is a positive way to solve this problem.However,since the cloud server may malfunction or even be malicious,the reliability of the search results returned by the server is challenged.Currently,how to verify the search results returned by the server has became a hot topic in academic community.Most of the existing schemes only support verifiable single keyword search and cannot achieve the publicly verifiable conjunctive keyword search effectively.When the result returned by the cloud server is an empty set,the overhead of verification is too expensive,which is not acceptable for resource constrained users.Therefore,it is of great significance to study the efficient publicly verifiable keyword search in cloud computing.Based on the malicious server model,we respectively propose a novel publicly verifiable exact and fuzzy conjunctive keyword search scheme in this thesis,which has been accepted by the International Journal of Embedded Systems(EI source journal).The main contributions are as follows:(1)Based on the existing works,we propose a novel verifiable exact keyword search scheme combining the techniques of the Merkle Hash Tree,bilinear-map accumulators and verifiable polynomial evaluation in this thesis.The scheme not only supports the public verifiability of the search results,but also can verify the correctness of the results efficiently even if the untrusted server returns an empty set deliberately.Finally,we prove that the proposed scheme is secure under malicious server model.(2)We use edit distance to quantify keywords similarity and use the wildcard-based technique to construct the fuzzy keyword sets for every keyword.We then propose a verifiable fuzzy conjunctive keyword search scheme combining the techniques of the Merkle Hash Tree,bilinear-map accumulators and verifiable polynomial evaluation.The scheme supports conjunctive keyword search,which enhances the functionality of the search.It also supports the public verifiability of the search results,which is suitable in the malicious server model.(3)We give a thorough experimental evaluation of our proposed scheme and we conduct the experiment using C language and the Pairing-Based Cryptography(PBC)library on Linux server.Furthermore,we compare our scheme with the related schemes from two aspects of theoretical analysis and experimental evaluation,and the simulation results indicate that our scheme is more efficient to verify the integrity of the search results,which plays an important role for the resource-constrained mobile terminal.