Research On Attribute-Based Encryption With Keyword Search In Cloud Storage

Cloud storage has many advantages,such as capacity expansibility,low cost,easy management and so on.It is favored by more and more enterprises and individual users.When data owners store data in the cloud,the physical control of the data is handed over to the cloud service provider.To prevent sensitive data from being stolen,data owners usually encrypt sensitive data before uploading them to the cloud.When data is stored in the cloud in the form of ciphertext,cloud service providers cannot effectively provide users with data retrieval services,which greatly reduce the efficiency of cloud data acquisition.Attribute-based encryption with keyword search(ABKS)supports multiple users to share keyword search ciphertext,which can better solve the problem of cloud users' terminal resource constraints,hidden access structure and the flexibility of search in ciphertext search.This thesis mainly focuses on the problem of keywords guessing attack,and proposes three kinds of keyword guessing attack resistant attribute-based encryption with keyword search scheme.The main work and innovation of this thesis are as follows:(1)An efficient-ABKS scheme is proposed(EABKS).Aiming at the problem of cloud users' terminal resource constraints,an efficient ABKS scheme based on the access structure of and-gate supports wildcards is proposed.The scheme uses the Vieta's formula,and the length of index and trapdoor are short,and the computation complexity of trapdoor algorithm and search algorithm is low;adopts the technique of secure channel free,and can resist the outside KGA by specifying a credible search server for users;uses the position to descript attribute,and makes each attribute can be denoted by only one element.Theoretical analysis shows that the proposed scheme is proven to be indistinguishable of chosen keywords attack secure and achieves trapdoor security in the standard model.Performance analysis and experimental simulation show that and the computational overhead and communication overhead of the proposed scheme are relatively small compared with other schemes.The scheme supports the application of ciphertext search in cloud storage,where the resource of user terminal is constrained.(2)An ABKS scheme with hiding access structure is proposed(HABKS).Aiming at the problem of hidden access structure in ABKS schemes,an ABKS scheme with hidden access structure is proposed based on multi-valued and-gate access structure.based on multi-value and-gate access structure,and the technique of ciphertext and key aggregation,the scheme achieves access structure hidden.A mechanism of search key negotiation mechanism participated by a trusted third party is designed,and the technique of remove security channel is adopted,which makes the scheme can resist inside and outside KGA.Theoretical analysis shows that the security of the scheme is proved to be secure in the standard model.Performance analysis and experimental simulation show that the scheme is efficient.The scheme provides support for the application of ciphertext search in cloud storage where access structure in ciphertext is sensitive.(3)An ABKS scheme supporting multiple keyword search is proposed(MABKS).Aiming at the flexibility of search,an ABKS scheme supporting multi keyword search is proposed based on LSSS access structure.The technique of online/offline is adopted,which improves the search efficiency and flexibility;a mechanism of index generation participated with the data owner's secret key is designed,which makes the scheme can resist both inside and outside KGA;the using conjunctive subset keyword search technology is used,which supports flexible conjunctive keyword search.The results of theoretical analysis show that the scheme is proved to be IND-CKA secure and trapdoor secure in standard model,and compared with the same type of scheme.Performance analysis and experimental simulation show that the proposed scheme has advantages in terms of efficiency.The scheme provides support for enhancing the flexibility of ciphertext search strategy in cloud storage.