Research On Leakage-Resilient Key-Aggregate Cryptosystem And Its Application In Cloud Access Control

With the rapid development of cloud computing,cloud storage has attracted people's attention in a new way of data storage.Cloud storage is evolved from cloud computing,which is used to upload local data to a cloud server for storage.This storage method is easy to use,low cost and scalable,and provides massive data sharing services.It becomes information storage area research focus.Data sharing is a very important issue in cloud storage.How to share partially encrypted data efficiently in cloud storage is a challenging issue.Therefore,based on the characteristics of cloud storage,a secure and efficient key aggregation system established and studied has very important application value.Based on the background of intelligent education cloud platform,starting from the actual demand of cloud,this dissertation focuses on the analysis and research of encryption scheme of key-aggregate Cryptosystem and aims to solve the problems of key leakage-resilient,key storage,access control and revocation of authority.The main work is as follows: Firstly,After Studing the key-aggregate scheme of Chu,it is found that the key-aggregate scheme deployed in the cloud terminal is vulnerable to side-channel attacks.To solve this problem,this thesis designs an anti-leakage key aggregation scheme,and proves the security of the scheme under the anti-auxiliary input CPA security model.The designed scheme can not safely recover the master key regardless of how many bits are leaked in the secret key,and the application in the intelligent education cloud terminal has more advantage than other schemes because of its efficiency.Secondly,based on the complete subtree method,a key-aggregate encryption scheme is designed to dynamically update user rights.The designed scheme not only has the characteristics of key-aggregate,but also dynamically revokes the access rights of users.Without the need to update the legal user key circumstances,it realizes the revocation of some user rights.In order to ensure the correctness of the revocation,it also provides a verification method.Compared with the original scheme,the user authority is effectively controlled when the cost of user key storage management is reduced,which is more suitable for practical application.