Research On Verifiable Ciphertext Search Algorithm In Cloud Storage Database

With the development of cloud storage technology,more and more users choose to store their data in the cloud.Therefore,The easy-using and security of cloud storage services are facing more challenges.To alleviate users' concerns about data security,cloud service providers need to meet higher security standards.In order to protect the privacy of user data,it is usually necessary to encrypt cloud storage data.However,the traditional encryption algorithm hides most of the data information,and the generated ciphertext is difficult to search and compare.Therefore,searchable encryption technology emerges as the times require.In order to improve the flexibility and security of ciphertext search algorithm,this thesis studies the connection keyword search technology and range search technology in untrusted environment.Aiming at the two scene of verifiable join keyword search and verifiable multi-condition range search,this thesis designs the corresponding data index structure and search algorithm respectively.The main work of this thesis is as follows:1.An index structure HPMT tree(Hash Prefix Merkle Tree)for verifiable data completeness is proposed.It guarantees the Correctness of nodes in the tree by using series Hash idea in Merkle tree.It determines the location of keywords in the tree by pseudorandom function,and provides unforgeable proof for keyword does not exist in the cloud.In addition,the HPMT tree constructs bilinear accumulator for all leaf nodes in the tree,which enables the algorithm to support multi-keyword intersection completeness verification using polynomial reciprocal conditions.2.A complete cloud storage database verifiable connection keyword ciphertext search algorithm is designed.It uses the proposed HPMT tree structure to test the completeness of multi-keyword intersection.Aiming at the characteristics of frequent updates of database,the algorithm uses Vector Commitment structure to prove the integrity of single-line data,which ensures the freshness of data,that is,data supports efficient dynamic updates.The algorithm uses broadcast encryption to realize key distribution and dynamic management of user privileges,and supports flexible multi-user operations.Finally,the security of the algorithm is analyzed,and the effectiveness and practicability of the scheme are proved by comparative experiments.3.An index structure OBMT tree(Order B + Merkle Tree)is proposed to verify the completeness of multi-conditional range search.Based on B + tree structure and series Hash idea in Merkle tree,using order revealing encryption algorithm to construct comparison trap.By constructing hierarchically bilinear accumulator in the tree,the efficiently completeness verification of search intersection of multi-conditional ranges is realized.4.A complete multi-condition verifiable range search algorithm for cloud storage database is designed.The proposed OBMT tree structure is used to verify the completeness of multi-conditional intersection.The algorithm effectively supports the dynamic update operation of data.Finally,the security of the design scheme is analyzed,and the feasibility and efficiency of the proposed scheme are verified by experimental analysis.