Research On Attribute-Based Encryption System In Cloud Storage Environment

Cloud storage technology has achieved increasingly widespread adoption in the enterprise,personal and government sectors,but along with frequent cloud data breaches,its security issues are coming to the fore.Since users lose direct physical control of data outsourced to the cloud,while cloud server providers may access and analyze data for illegal purposes,data security and privacy issues become a major concern for users when using cloud services.While traditional symmetric or asymmetric encryption can ensure data confidentiality,it cannot meet the demand for flexible and efficient data sharing and management.Attribute-based encryption,as an emerging,one-to-many encryption algorithm,is the most effective way to simultaneously guarantee data confidentiality and fine-grained access control in a cloud environment.In this paper,we focus on designing attribute-based encryption schemes for cloud environments,covering blockchain,key escrow issues,and leakage resistance.The main research work is as follows:1.Blockchain-aided attribute-based searchable encryption.To address the problems of decryption computation burden and massive user key management that arise when implementing attribute-based schemes in cloud storage,a revocable,outsourced decryption,and searchable attribute-based encryption scheme with efficient revocation and decryption functions is designed by combining consortium blockchain.Replacing the traditional centralized server with a distributed blockchain system,all revocation tasks are performed by the blockchain,and re-encryption of ciphertext and key update are no longer required.In addition,the solution can perform pre-decryption operations in the cloud,and users only need to spend a small amount of computational cost to achieve decryption operations.Both theoretical analysis and experimental results show that the scheme has high efficiency.2.Attribute-based encryption with key escrow-free.To address the key escrow problem inherent in attribute-based encryption,we combine Two-party Computation protocol to design a revocable,blockchain-aided,outsourced decrypted attribute-based encryption scheme with key escrow-free,which can resist conspiracy attacks between malicious users and revoked users.The key is calculated using a secure key issuance protocol,and the blockchain cannot obtain the user’s secret value and generate the complete key independently,thus effectively solving the key escrow problem.Theoretical analysis and experimental results show that the scheme is effective.3.Leakage Resistant Attribute-Based Encryption.An attribute-based encryption scheme is designed under the continuous auxiliary input post-challenge leakage model.The scheme considers the impact of key leakage on the cryptosystem after the challenge phase,and the proposed scheme is also resistant to continuous leakage if the key is updated periodically,and achieves auxiliary input leakage using the Goldreich-Levin theorem.The security of the proposed scheme is proved using dual-system cryptography based on three modified static assumptions under the standard model.Finally,the scheme is shown to be effective by comparing its performance with other schemes.