Research On Outsourcing Computing Of The Attribute-based Encryption Scheme

Attribute-based encryption scheme can realize fine-grained access control.It is able to realize the information transformation and sharing in a region or group conveniently and securely.But the complicated encryption and decryption operations limit its usage in resource-limited devices and have become the key factor that prevents its development.Using outsourcing computing technology,most of the encryption and decryption operations can be outsourced to the cloud server.It means that outsourcing computing technology is able to reduce users computing resource,effectively.Nevertheless,several of these methods exist some problems in the efficiency and security.For the further development of attribute-based encryption scheme,it is vital to solve these problems.Therefore,starting from the existing work,this thesis focuses on the efficiency of outsourcing computing methods and the security of theses attribute-based encryption scheme.This thesis tries to design the secure and efficient attribute-based encryption and heterogeneous attribute-based signcryption scheme with outsourcing computing.Based on this,the main research contents of this thesis are as follows:(1)This thesis analyzes Li et al.'s attribute-based encryption scheme with outsourcing computing.The result shows that the scheme is not secure.Then we improve this scheme and design an attribute-based encryption scheme with outsourcing decryption which is indistinguishable under adaptive chosen ciphertext attack.(2)We propose two multi-authority attribute-based encryption schemes for outsourcing decryption with different security.These two schemes reduce user's computation resource consumption in the decryption stage.The transformation keys will be generated by the attribute authority.That is to say,these two schemes lift the restriction that only the user can generate the transformation keys.Which means that reducing the user's decryption time will not add extra computation.At the same time,this scheme uses the online/offline encryption technology to reduce user's online encryption time.(3)We propose a signcryption scheme by introducing the identity-based signature scheme into the attribute-based encryption scheme with outsourcing computation of(1).This scheme realizes encryption and signature in a logical step.This scheme combines the advantages of the attribute-based encryption scheme and the identity-based signature scheme.It solves the problem that the attribute-based encryption scheme cannot track the identity of the message sender.At the same time,the use of outsourcing computing technology reduces user's computing resource on encryption and decryption.