Research On Attribute-based Encryption Scheme Supporting User Accountability In Cloud Storag

With the rapid development of Internet technology,cloud storage has become an extremely important way of storing data.However,due to the openness and sharing nature of cloud storage,data security has become an urgent problem that needs to be addressed.While traditional encryption technology can protect data,there are issues with key management and fine-grained access control.Therefore,attribute-based encryption technology has emerged as a solution that can effectively solve these problems.However,the keys in attribute-based encryption protocols are not related to the identities of authorized users,but only to their attributes,which means that malicious authorized users may sell their private keys to obtain benefits.In addition,access policies stored in plaintext also involve users’ privacy information.Furthermore,the limited computing power of local users also affects the application of the system.To address the above issues of key abuse,privacy protection,and high computation cost,this thesis proposes corresponding solutions as follows:1)Accountable attribute-based encryption protocol based on a reward-punishment revocation mechanismTo address the problem of key abuse and high local computing cost in the system,this thesis proposes an accountable attribute-based encryption protocol based on a reward and punishment revocation mechanism,which firstly introduces a limited number of access mechanism to limit the number of times a user can access data in the cloud.If the threshold value is exceeded,the user is at risk of private key leakage and the attribute center actively traces the user’s identity information.At the same time,the user’s identity information is embedded in the private key for passive tracing.Secondly,the protocol establishes a rewardpunishment revocation mechanism to reward trustworthy users and revoke access permissions for malicious users.In addition,the use of proxy servers can outsource decryption and reduce local user computational cost.Finally,the security analysis and performance analysis prove that this protocol has significant advantages.2)Accountable multi-authority attribute-based encryption protocol with policy hidingThis thesis proposes an accountable multi-authority attribute-based encryption protocol with policy hiding to address the issues of privacy leakage and high computation cost in revocation process.First,the protocol introduces multi-authority to assist users in key generation,solving the problem of excessive permissions for a single attribute authority and improving the efficiency of key generation.Second,the protocol traces malicious users through the cloud and revokes their access using attribute version updates to reduce the computational cost of the revocation process,and it increases non-imputability to prevent the cloud from maliciously accusing honest users.In addition,the protocol utilizes one-way anonymous key protocol to achieve full policy hiding and ensure data privacy and security.Finally,security analysis shows that the protocol has high security and can resist collusion attacks,and performance analysis demonstrates its scalability and efficiency over other protocols.