Research On Cloud Data Sharing Scheme Based On Blockchain And Attribute-based Encryption

As a new generation of network computing mode,cloud computing provides users with flexible,personalized and convenient services.Cloud storage services help individuals or enterprises to access their data stored in the cloud anytime and anywhere,reducing the burden of storing and managing data locally.However,out of concerns about data security and privacy leakage,users do not want to outsource private data to the cloud,because after uploading private data to the cloud,data ownership and physical control are separated,posing a serious threat to data security.People are worried that data stored in the cloud will be accessed illegally or that cloud service providers will directly and illegally sell user data.In order to solve the above-mentioned problems,traditional methods store encrypted data in the cloud to ensure data security,but data sharing is extremely inconvenient.Attribute-based encryption technology has one-to-many data encryption features and finegrained access control capabilities,which is very suitable for the safe and efficient sharing of data in the cloud.However,the traditional attribute-based encryption technology has a bilinear pairing operation with a large computational overhead,which is not suitable for resource-constrained cloud terminal users.The performance bottleneck of the traditional single-authorization attribute-based encryption scheme prevents it from being applied to scenarios with massive cloud users.In actual applications,user attribute changes,key leaks,and attribute expiration may occur.In order to ensure data security,it is necessary to update the key and ciphertext in a timely and effective manner.In addition,the system also needs to guard against collusion attacks between users.In response to the above problems,the main research done in this article is as follows:1.This paper proposes an attribute-based encryption scheme based on ECC and supporting revocation.Using the OBDD structure with rich expression ability and low computational complexity,it can reduce redundant attributes to shorten the length of the ciphertext and improve the efficiency of the system.Compared with the pairing operation on bilinear group,scalar multiplication on elliptic curve not only keeps the same security,but also reduces the demand for computing resources.Subset coverage technology is used to realize fine-grained attribute or user revocation and update the ciphertext and key to prevent the revoked user from continuing to access.Security and performance analysis shows that the proposed scheme improves the efficiency and security of the system.2.This paper proposed a cloud data sharing scheme based on multi authority of blockchain.The proposed scheme decides the system attribute set into several disjoint attribute subset,so that each authority is responsible for one or more disjoint subsets,which reduces the harm caused by single attribute authority being broken,and solves the system performance bottleneck.An attribute group is established for each attribute,which is composed of users with the attribute.When the attribute group key is generated for users,the user identity is combined with the attribute group key to prevent collusion attack between users.For users with limited computing resources,the pairing operation in decryption can be outsourced to the cloud computing platform.The introduction of blackchain technology enables users with computing power to keep accounts together with the attribute authorization agencies of relevant interests,forms restrictions between users and attributes authorization agencies,realizes the traceability of the system,effectively prevents mutual repudiation in all parties,and improves the scalability of the system.Security and performance analysis show that the propose scheme has higher efficiency than other schemes on the basis of ensuring data security.