Research On Key Technologies Of Verifiable Outsourced Computation For Cloud Computing

The combination of the Internet development and the increasing use of mobile devices makes it easier to gain information.As the amount of information gets larger,more and more computation tasks need to be done.When people want to store the information they got,and want the computation to be done,the lack of computing power of the weak devices manifests itself.Therefore,people naturally choose to delegate these computing tasks to entities with more powerful computing ability.Cloud computing,with its flexible and convenient way to rent,powerful and stable computing ability,is the best choice for the implementation of this task.But only the correct result makes sense to the user.In the face of untrusted cloud computing environments,it becomes one of the hot topics in the field of cloud computing that how to ensure the cloud servers to execute the client's computing tasks honestly and correctly.A solution to this problem is that the cloud servers return a proof as well as the computing result to the client.So that clients can verify the results efficiently and conveniently by using the proof.For this,many researchers at home and abroad have carried out extensive and in-depth research on how to produce the proof information,and several schemes for different application scenarios have also appeared.However,there are still some deficiencies in the actual application of these schemes.Therefore,this paper focuses on the problem of verifiable computation in cloud computing environment,and improves the shortcomings of different types of researches by using cryptography tools such as attribute based encryption,bilinear map,fully homomorphic encryption and garbled circuits.Verifiable computation schemes are also proposed to satisfy the requirement of different scenarios.The main work and achievements of this paper are as follows.(1)In the current public verifiable computing schemes,few support efficient updating of computing functions and a preprocess has to be executed for the input before the client initiates a computing request.So a new verifiable computation model is proposed for supporting the update of the computation by using the authenticated data structure.The algorithms and security property are formalized and a proof to the result has been computing out by using the bilinear map and the polynomial decomposition theorem.A detail construction of the scheme which is proved secure is presented before the analysis of the algorithms complexity.(2)In the current multi-client verifiable computation researches,the privacy of the clients' inputs cannot be guaranteed.And clients need to interact with each other while no access control is in the schemes.A model for multi-client non-interactive verifiable computation is proposed,and algorithms and security properties are formalized.The proxy oblivious transfer protocol is improved by using key policy attribute based encryption in order to add access control.After that a scheme for multi-client non-interactive verifiable computation scheme is presented using FHE and garbled circuits.The security and privacy are proved.The scheme has certain advantages when compared with other schemes.(3)In the current researches for the verifiable outsourced intersection,either only the intersection between plaintext sets can be done or the verifiability of the result cannot be achieved.Two new schemes for both plaintext and ciphertext intersection are proposed using the bilinear-map accumulator and the re-encryption.In the scheme for ciphertext,the intersection can be executed by the cloud without having the ability to decrypt the sets.The security of the schemes is based on the q-strong bilinear DH assumption and DL assumption.The analysis of the algorithm complexity comes last.(4)In the current researches for the multi-servers verifiable computation,when the cloud servers return an incorrect result which is detected by the client,the client will initialize another request again,but no more punishment is carried out for the dishonest server.So this paper proposes a new scheme called revocable public verifiable computation scheme by using the revocable KP-ABE structure.The public verifiability,revocation,vindictive servers and blind verifiability of the scheme are proved by using Game experiments.A prototype system is constructed in detail,and the functions and classes are designed and realized.Finally,the function and performance of the prototype system are tested.