Research On High-Performance Homomorphic Attributed-based Encryption

As one of the important development trends of IT industry,cloud computing technology makes full use of information resources and provides high-quality services.While cloud computing services bring convenience to users,they also bring potential risks to users' privacy.In the field of cloud computing,computing and data sharing are considered to be the two most important services.Therefore,in the field of cloud computing security,computing security and data sharing security are considered to be the two most hot directions.In the quantum computer era,lattice-based fully homomorphic encryption and attribute-based encryption play an important role in computing security and data sharing security respectively.In the cloud computing service scenario,sometimes computing security and data sharing security need to be considered at the same time.Therefore,this thesis studies homomorphic attribute-based encryption technology,focuses on efficient computing of private data and fine-grained user access control,and strives to resolve the single point failure of key generation center,attribute-hiding and user-revocable.The research content of this thesis is divided into the following three parts.(1)At present,the compact homomorphic attribute-based encryption scheme is only applicable to the random oracle model,and need to obtain part of the private key in the process of ciphertext homomorphic calculation.To solve above problems,this thesis constructed a compact multi-target additive homomorphic attribute-based encryption in the standard model,that enables ciphertext associated with different attributes under the same access policy set to be additive homomorphic in the presence of the cloud server,at the same time satisfies the compact property that the size of ciphertext after homomorphism calculation is independent of the number of ciphertext input in the calculation process.Among them,the access strategy is a Boolean circuit of any polynomial size(with limited depth)to achieve precise user access control effect.(2)Aiming at the fact that the public parameters of the revocable predicate encryption scheme are too large and only selective security is achieved,a semi-adaptive security revocable predicate encryption scheme is designed.In this thesis,the semiadaptive security technique and the direct revocation technique are used to make the scheme support the public parameters of fixed length and stronger security.On this basis,we combine the revocable predicate encryption scheme with the multi-key fully homomorphic encryption technique to construct a revocable homomorphic predicate encryption scheme,so that ciphertext associated with different attributes can be homomorphic calculation.(3)In order to effectively solve the problem of single point failure that may occur in the key generation center of the scheme in the previous section,a multi-authority keypolicy attribute-based encryption scheme is proposed,which the access strategy is a Boolean circuit.In this scheme,decentralized authorities independently establish their own master private keys and public parameters.The cryptographer selects a set of trusted authorities and uses their public parameters to encrypt the data.The ciphertext can be decrypted correctly if and only if the encryptor's attributes satisfy the access policy in the decentralized authority.