Research And Application Of Attribute-based Encryption For General Circuit

Attribute-based Encryption(ABE)features a mechanism where a set of attributes can be used as the identity of users,and attribute set and access policies can be associated with private key of user and the ciphertext.When user's attribute set satisfies the access structure,the ciphertext can only be decrypted to realize flexible access control.However,the challenge of expanding the access structure to make general circuit has been resistant to backtracking attack.So,this thesis researches on existing attribute-based encryption for general circuit,which can resist backtracking attacks,and it has higher security and more expressive ability.In thesis,the Attribute-based encryption for general circuit is improved,and the inproved scheme is applied to a variety of scenarios,providing more secure and efficient attribute encryption scheme.This thesis first proposes an attribute-based encryption scheme for general circuit which inproves the general circuit,making its ciphertext shorter,and more suitable for various application scenarios.Second,an attribute-based encryption scheme supporting multiple owners is proposed.Current attribute-based encryption system only has a single owner,ignoring the multi-owner access control.To ensure the user has control over the access list,attribute-based encryption scheme supporting multiple owners is proposed.The scheme allows owner to specify a group of co-owners and the ciphertext encrypted by the owner can be expanded according some rules.Rules including access policy reduction and access policy expansion prevent the access policy conflict between the owners,which may causes no user to be able to decrypt the ciphertext.In access policy reduction,all the owners are at the same priority.The user must satisfy the all owner's access policies to decrypt.As opposed to access policy reduction,owner has a higher priority comparing to co-owner in access policy expansion,and users can only decrypt if they satisfy the owner's or all co-owner's access policies.Moreover,this thesis proposes a searchable encryption for general circuit.The proposed scheme outsource part of decryption to reduce the burden on users.When the search is successful,the cloud service center will perform partial decryption at the same time and only a small amount of calculation is required for user to do the decryption.Finally,combining the multi-owner encryption for general circuit with searchable encryption for general circuit,a multi-owner searchable encryption scheme based on general circuits is proposed which realizes the access control,and is suitable for multi-owner scenarios.Security proof,performance analysis and experimental simulation show the effectiveness and efficiency of the proposed scheme.