Research And Application Of Attribute-based Encryption Scheme Supporting Traitor Tracing

In recent years,with the rapid development of the Internet,the security of data under the Internet is facing severe challenges.Attribute-based encryption,as a fine-grained access control method,realizes flexible control of user access permissions and realizes "one-to-many" fine-grained sharing of private data through effective matching of attribute sets and access policies.However,in the practical application of attribute-based encryption,there are some drawbacks,such as the user revealing the key intentionally or unintentionally.At this time,since users with the same attribute set have the same decryption authority,it is impossible to pursue accountability for malicious users who leaked the key.Therefore,it is necessary to research an attribute-based encryption scheme that supports traitor tracking.At present,attribute-based encryption schemes that support traitor tracking have problems such as key escrow,low efficiency,and inflexible access control strategies.In view of the above problems,this paper improves the scheme to build an efficient attribute-based encryption scheme that prevents key abuse,so as to realize the privacy protection and fine-grained controllable rewrite of the blockchain.The work of this paper is mainly divided into three parts:Firstly,in the existing attribute-based encryption schemes that support traitor tracking,the user's key is completely generated by the semi-trusted authority,which leads to the key escrow problem in the scheme.In order to solve the key escrow problem,this paper introduces fully homomorphic encryption,which generates the user's key through the interaction between the cloud and the authority.At the same time,the user signature is introduced in the scheme to prevent authoritative organizations and the cloud from colluding to forge user keys,which effectively solves the problem of abusing the key and realizes the privacy protection of data.Secondly,in view of the low efficiency,key abuse and insufficient flexibility of access control policies for data privacy protection and sharing on the blockchain,an enhanced attribute-based encryption scheme that supports traitor tracking is proposed.This scheme effectively shortens the length of the ciphertext and key,and supports the accountability of malicious users who leak private keys.At the same time,the scheme also implements dynamic access control,in which data owners can flexibly update access control policies.Thirdly,in order to realize the rewriting of the blockchain in a flexible,fine-grained and controllable way,this paper applies an improved traceable attribute-based encryption scheme to the chameleon hash function.This scheme implements the chameleon hash function based on access policy and supports large attribute set.In addition,in order to effectively prevent the abuse of blockchain rewrite right,a rebellion tracking function has been added.Once a user is found to abuse the blockchain rewrite right,the authority will immediately implement the traitor tracking to hold malicious users accountable.