Decentralized Multi-Authority Attribute-Based Encryption For Privacy Protection In Cloud

Cloud computing meets the needs of data storage and data sharing,and takes on the responsibility of managing private data.However,the privacy protection problem has not been optimistic,and privacy leakage cases are also common in the cloud computing.Therefore,the primary goal in Cloud is to protect data security at present.Due to the fact that a decentralized multi-authority attribute-based encryption(D-MA-ABE)not only supports fine-grained access control to the encrypted data,but also can achieve the privacy-preserving,D-MA-ABE has been a hot topic recently.The thesis focuses on data privacy preserving,and proposes D-MA-ABE schemes with privacy preserving.The main work accomplished are as follows:Firstly,a D-MA-ABE scheme with fully hidden access policy is proposed.In the traditional ABE scheme,the message is encrypted by the access policy containing some sensitive privacy information,which may lead to the disclosure of user privacy.Therefore,the ABE scheme with hidden access policy emerges.In the existing ABE researches,each attribute in the access policy is represented as a couple: the attribute name and the attribute value,and hiding access policy is generally realized through hiding the attribute value.However,it can be found that the access policy only is partially hidden.In order to solve the above problems,a D-MA-ABE scheme with fully hidden access policy is presented in the thesis.Combing with the technique of IPE and ABE to implement the fully hidden access policy,the access policy is fuzzy by converting it into a vector.The number of ciphertext and secret keys in this scheme is only concerned with the number of wildcards.In order to further improve the decryption efficiency of users,most of the heavy computation in the scheme is outsourced to reduce the time cost of online computation of users.The security of the proposed scheme is reduced to the standard DBDH and DLIN assumptions.The performance analysis shows this scheme has obvious advantages over the existing schemes.Secondly,a decentralized multi-authority attribute-based access control extension scheme for privacy protection in smart grid is proposed.The real-time electricity data has high economic value,so the application prospect of the smart grid systems is very broad.D-MA-ABE for privacy protection is a promising tool to solve this challenge,but it is anurgent problem to be solved about applying it into the system.Hence,a decentralized multi-authority attribute-based access control scheme for privacy protection in smart grid is proposed in this thesis.Compared with the existing schemes,this scheme supports a more flexible threshold access policy while implementing fully hidden access policy.In order to improve the efficiency,we add the test phase to avoid unnecessary operations before data recovery.In addition,it is proved to be adaptive security under the k-Linear assumption.The performance analysis shows that this scheme has obvious advantages in similar schemes.