Research On Data Integrity Auditing Method Based On Shamir Threshold Signature In Cloud-fog Environment

With the advent of the era of big data,users with massive data storage needs will choose to upload their data sets to the cloud with sufficient storage capacity.Although the storage pressure will be relieved after uploading data to the cloud,users also lose direct control over their important data.The data stored in the cloud can be corrupted for a variety of reasons,but the cloud providing the storage service may choose to hide the fact that the data has been corrupted in order to protect its reputation.In order to solve this problem,scholars at home and abroad have put forward many distinctive data integrity auditing protocols.The vast majority of these auditing protocols assist users with data checks by introducing an auditor who specializes in performing auditing tasks.However,with the rise of fog computing,cloud-fog environment has been gradually developed.Compared with the traditional cloud storage environment,a major feature of the cloudfog environment is the appearance of fog nodes.These fog nodes have a large number of computing and storage capabilities,which can completely replace the functions of thirdparty auditors in traditional cloud storage auditing protocols.Based on this,this paper studies the data security in cloud environment and designs two kinds of data integrity auditing protocols that are suitable for cloud-fog environment.In addition,Shamir threshold signature technology is introduced in the process of designing auditing protocols,which makes the two auditing protocols designed in this paper meet the needs of group users and close to the real scene.The main contributions of this paper are as follows:(1)A data integrity auditing protocol is designed to support privacy protection and dynamic updating of designated verifiers in cloud-fog environment.This protocol not only realizes the secure and efficient data auditing task,but also implements the function of specifying validators by issuing tokens for fog nodes.Only fog nodes with legitimate tokens can perform data auditing tasks,and tokens can be updated at any time,thus enabling the addition and withdrawal of fog node groups designated to perform auditing tasks.In addition,this agreement also takes into account the security of sensitive user information.In the process of auditing,the blind factor is introduced to realize the privacy of user data and the anonymity of identity.(2)A multi-cloud and multi-replica data integrity auditing protocol that supports dynamic data update in cloud-fog environment is designed.In order to prevent data from being damaged and cannot be recovered,users are allowed to upload their data to multiple cloud at their own discretion,and each server can store a different number of copies of data.In order to prevent collusive attacks on these cloud servers,this protocol introduces a symmetric encryption calculation to generate different copies of the same data file.This process is equivalent to encrypting data files,protecting the privacy of data and preventing collusion attacks at the expense of computing resources.In this agreement,the fog node also plays the role of auditor and is designated by the user.In addition,in order to support users to make certain changes to the data stored in the cloud,this protocol uses a tree data structure Merkle hash tree in the design process to support users to insert,modify and delete their own data.In this paper,the security proof of the two designed auditing protocols is given under the random oracle model,and the designed auditing protocol is compared with other auditing protocols from the aspects of theoretical analysis and experimental simulation.The final results show that the two auditing protocols designed in this paper are secure and efficient.