Research On Cloud Data Security Sharing Based On Traceable And Revocable Attribute-based Encryption

Driven by new information technology,all kinds of data are rapidly expanding on an unprecedented scale,and the demand for storage space has increased dramatically.Cloud servers have become the first choice for storing and processing data due to its advantages of low cost,easy access,and scalability.However,after the data is uploaded to the cloud platform,the data user loses the right to manage the data,and the cloud server,as a semitrusted third-party entity,cannot fully guarantee the safe storage of data.Attribute-based encryption technology is an encryption technology suitable for cloud storage.It realizes secure access to data in cloud servers through "one-to-many" fine-grained access control.However,in practical applications,there are cases of users leaking keys and permission changes.To ensure that data is not accessed illegally,users who leak keys need to be tracked and their access rights revoked at the same time.In this paper,we focus on the key tracking and user revocation problems of attribute encryption in cloud storage,and the specific work is as follows.First,in view of the slow update speed of user permissions in the current ciphertext policy attribute-based encryption scheme,an efficient traceable and revocable attributebased encryption scheme in cloud storage is proposed.The scheme can identify and track malicious users,realize user revocation and attribute revocation through the user revocation list and attribute group key respectively,and apply the constructed scheme to cloud storage to ensure fine-grained access control of data;In order to decrease the loss of computing resources of smart terminals,most of the decryption and attribute revocation operations are entrusted to the cloud server for processing;Based on the difficult assumption of computing Diffie-Hellman,it is proved that the scheme has chosen plaintext security under the standard model;The simulation experiment shows that the time required for the scheme to update the ciphertext is stable at about 0.022 seconds,and the efficiency has been significantly improved compared with other schemes.Second,to solve the issues of coarse-grained rewriting,abuse of rewriting power and lack of revocation mechanism in blockchain rewriting,an accountable and revocable blockchain rewriting scheme based on attribute cryptosystems is proposed.This approach integrates several cryptographic primitives including a chameleon-hashes with ephemeral trapdoors,a traceable and revocable attribute-based encryption scheme and a linkable ring signature scheme based on the SM9 algorithm.Not only can it effectively identify and track users who maliciously modify transactions,but it can also limit their ability to obtain temporary trapdoors,providing a more flexible and detailed access control method for transaction management;Based on the decisional linear assumption,it is proved that the scheme is adaptively safe under the standard model;Theoretical and experimental analysis shows that the scheme performs well in all aspects and has obvious advantages.