Research And Application Of Accountable Attribute-based Encryption Scheme

In the era of big data,although the traditional public key encryption mechanism can achieve privacy protection,it can not meet the requirements of fine-grained access control.In contrast,attribute-based encryption can assign the right to decrypt data according to the attributes owned by the user,which is more flexible and efficient than the traditional public key encryption mechanism.However,with the development of attribute-based encryption,some problems have emerged,among which the more prominent one is the abuse of key.There are two kinds of existing problems of key abuse,one is that the authority distributes the key to unauthorized users,and the other is that authorized users disclose the key to unauthorized users.Either of these situations will pose a threat to the confidentiality of the system.In order to solve the problem of key abuse,the accountable attribute-based encryption mechanism is proposed.For the users in the system who illegally divulge the private key for personal benefit,the accountable attribute-based encryption mechanism can use the leaked key to find the owner of the key,which can be traced back to the malicious user.In this thesis,the accountable attribute-based encryption mechanism is deeply studied and analyzed,combined with the characteristics of user revocation,public audit,scheme efficiency.Compared with the existing classical research results,the advantages of the proposed scheme and the future work objectives are obtained.Specifically,the main research results of this paper are as follows:(1)A ciphertext policy attribute-based encryption scheme is proposed in this thesis,which realizes arbitrary monotonous access structure,traceable user and accountable authority.Specifically,this thesis use an auditor to make a fair ruling on malicious users.Furthermore,so as to settle the matter of system permission revocation when users leave the system and misbehaving users,this thesis utilizes an indirect revocation manner based on trust tree to realize revocation.Compared with the existing schemes,this scheme achieves user revocation with an acceptable time cost.Finally,in the standard model,the scheme is proved to be fully secure.(2)In this thesis,an efficient traceable attribute-based encryption scheme which supports user revocation is proposed.This scheme can not only trace malicious users,but also revoke malicious users and users who exit from the system in time,so as to ensure that such users can no longer access the encrypted data stored in the cloud server.Considering the efficiency of the scheme,the use of constant-length ciphertext and key not only improves the efficiency of ciphertext and key transmission,but also greatly reduces the time spent on decryption operation.In addition,the storage overhead for traceability in this scheme is fixed.At the same time,this thesis gives the security proof and experimental analysis of the scheme,which shows the availability of the scheme.(3)This thesis gives the application prospect of the proposed scheme,one is based on the brain neurological diagnosis and treatment data intelligent assistant developed by the Guangdong Joint Fund of the National Nature Fund,and the other is a scene of the Internet of things.At the same time,the neural diagnosis and treatment intelligent assistant system model and the Internet of things system model are given.