Research On Access Control Of Searchable Encryption In Multi-User Setting

With the rapid development of information technology such as big data and artificial intelligence,people now are paying more attention to information security.As one represent of information security technology,cryptography has been playing a very important role in protecting data.At the same time,information technology provides a broad background and support for the development and application of cryptography.In this paper,we study the public key searchable encryption and mainly focus on access control and key management in the multi-user setting.First,to protect sessions from eavesdropping,based on the classic Diffie-Hellman key agreement protocol,this paper constructs a two-party authenticated key agreement protocol with the use of bilinear mapping.The shared key will be used to protect sessions between users.As an auxiliary tool of searchable encryption system,this protocol algorithm can resist unknown key sharing attacks and improve the security of the system.As to main contents,to achieve more fine-grained and flexible access control mechanism,in the first scheme,the manager classifies his data and authorizes users according to categories.The cloud server in this scheme builds an access control matrix,which will be used to verify whether a trapdoor is valid or not.By this way can we achieve access control and narrow search range at the same time.Also we do not need a trusted center to do the key management.In the multi-user setting of public key searchable encryption,it is generally necessary to generate indexes as many as the number of users,which is a waste of resource.This paper constructs another searchable encryption based on identity,whose users on different levels should have different keys in length.In other words,a user's identity and secret key relates to his rights to search.Every user is able to search data encrypted by others whose level is lower than his.By this way can achieve vertical management of access control.