Efficient Multi-Authority Attribute-Based Searchable Encryption Scheme with Blockchain Assistance for Cloud-Edge Coordination

Cloud storage and edge computing are utilized to address the storage and computational challenges arising from the exponential data growth in IoT.However,data privacy is potentially risky when data is outsourced to cloud servers or edge services.While data encryption ensures data confidentiality,it can impede data sharing and retrieval.Attribute-based searchable encryption(ABSE)is proposed as an effective technique for enhancing data security and privacy.Nevertheless,ABSE has its limitations,such as single attribute authorization failure,privacy leakage during the search process,and high decryption overhead.This paper presents a novel approach called the blockchain-assisted efficientmulti-authority attribute-based searchable encryption scheme(BEM-ABSE)for cloudedge collaboration scenarios to address these issues.BEM-ABSE leverages a consortium blockchain to replace the central authentication center for global public parameter management.It incorporates smart contracts to facilitate reliable and fair ciphertext keyword search and decryption result verification.To minimize the computing burden on resource-constrained devices,BEM-ABSE adopts an online/offline hybrid mechanism during the encryption process and a verifiable edge-assisted decryption mechanism.This ensures both low computation cost and reliable ciphertext.Security analysis conducted under the random oracle model demonstrates that BEM-ABSE is resistant to indistinguishable chosen keyword attacks(IND-CKA)and indistinguishable chosen plaintext attacks(INDCPA).Theoretical analysis and simulation results confirm that BEM-ABSE significantly improves computational efficiency compared to existing solutions.

NC-MACPABE: Non-centered multi-authority proxy re-encryption based on CP-ABE for cloud storage systems

The cloud storage service cannot be completely trusted because of the separation of data management and ownership, leading to the difficulty of data privacy protection. In order to protect the privacy of data on untrusted servers of cloud storage, a novel multi-authority access control scheme without a trustworthy central authority has been proposed based on CP-ABE for cloud storage systems, called non-centered multi-authority proxy re-encryption based on the cipher-text policy attribute-based encryption(NC-MACPABE). NC-MACPABE optimizes the weighted access structure(WAS) allowing different levels of operation on the same file in cloud storage system. The concept of identity dyeing is introduced to improve the users' information privacy further. The re-encryption algorithm is improved in the scheme so that the data owner can revoke user's access right in a more flexible way. The scheme is proved to be secure. And the experimental results also show that removing the central authority can resolve the existing performance bottleneck in the multi-authority architecture with a central authority, which significantly improves user experience when a large number of users apply for accesses to the cloud storage system at the same time.

Research on Multi-Authority CP-ABE Access Control Model in Multicloud

In order to solve the problems of data sharing security and policy conflict in multicloud storage systems(MCSS), this work designs an attribute mapping mechanism that extends ciphertext policy attribute-based encryption(CP-ABE), and proposes a multi-authority CP-ABE access control model that satisfies the need for multicloud storage access control. The mapping mechanism mainly involves the tree structure of CP-ABE and provides support for the types of attribute values. The framework and workflow of the model are described in detail. The effectiveness of the model is verified by building a simple prototype system, and the performance of the prototype system is analyzed. The results suggest that the proposed model is of theoretical and practical significance for access control research in MCSS. The CP-ABE has better performance in terms of computation time overhead than other models.

Multi-authority proxy re-encryption based on CPABE for cloud storage systems

The dissociation between data management and data ownership makes it difficult to protect data security and privacy in cloud storage systems.Traditional encryption technologies are not suitable for data protection in cloud storage systems.A novel multi-authority proxy re-encryption mechanism based on ciphertext-policy attribute-based encryption（MPRE-CPABE） is proposed for cloud storage systems.MPRE-CPABE requires data owner to split each file into two blocks,one big block and one small block.The small block is used to encrypt the big one as the private key,and then the encrypted big block will be uploaded to the cloud storage system.Even if the uploaded big block of file is stolen,illegal users cannot get the complete information of the file easily.Ciphertext-policy attribute-based encryption（CPABE）is always criticized for its heavy overload and insecure issues when distributing keys or revoking user＇s access right.MPRE-CPABE applies CPABE to the multi-authority cloud storage system,and solves the above issues.The weighted access structure（WAS） is proposed to support a variety of fine-grained threshold access control policy in multi-authority environments,and reduce the computational cost of key distribution.Meanwhile,MPRE-CPABE uses proxy re-encryption to reduce the computational cost of access revocation.Experiments are implemented on platforms of Ubuntu and CloudSim.Experimental results show that MPRE-CPABE can greatly reduce the computational cost of the generation of key components and the revocation of user＇s access right.MPRE-CPABE is also proved secure under the security model of decisional bilinear Diffie-Hellman（DBDH）.

Blockchain Access Control Scheme Based on Multi-authority Attribute-Based Encryption

Blockchain has been widely used in many fields because it can solve the problem of information asymmetry and enable users who do not trust each other to collaborate without the participation of third-party intermediaries.Existing blockchain access control schemes usually use attribute-based encryption,but most of them adopt traditional single-attribute authority for attribute authorization,which has the problem that the authority is overburdened and must be fully credible.This paper proposes a blockchain access control scheme based on multiauthority attribute-based encryption by improving the existing blockchain privacy protection method.Autonomous identity management is performed through the blockchain to complete the initialization of user identity and the issuance of attribute certificates.Attribute authorities are selected using the reputation proof consensusmechanism.The distributed key generation protocol is used to generate keys,and the linear secret sharing scheme is improved.The hierarchical relationship of the access structure is used to encrypt and access control the private data that need to be uploaded to the blockchain.According to the comparison with other blockchain access control schemes,the scheme proposed in this paper has been improved in terms of security and efficiency.

A time dimension of paper influence evaluation research:Improvement based on AMMAA algorithm

Aiming at the deficiency of h index and the lack of a comprehensive and effective evaluation index,this paper introduces an ammaa algorithm for paper evaluation and proposes an optimization algorithm integrating time dimension:t-ammaa algorithm,which reflects the influence evaluation of individual scholars through the evaluation of paper influence.We used Web of Science as the data source and focused on the paper published by the authors of Chinese library and info rmation science,to calculate the ammaa value and t-ammaa value of these papers,and then obtained the ammaa value and t-ammaa value of the scholar.The result ranking of the two algorithms and the scholar’s H-value ranking are normalized for empirical comparison and analysis.The results show that t-ammaa algorithm considering the cited times,the cited threshold limit,the co-authors’number,and the temporal heterogeneity of the cited papers,is a more reasonable measurement method for evaluating the influence of scholars.It can not only comprehensively evaluate the influence of single author and co-authored paper,but also eliminate the influence brought by time factor.

BDAE: A Blockchain-Based and Decentralized Attribute-Based Encryption Scheme for Secure Data Sharing

Ciphertext-policy attribute-based encryption(CP-ABE) is widely employed for secure data sharing and access control. However, its dependence on a single authority introduces security and performance challenges. Despite the existence of multi-authority CPABE approaches, persistent issues such as single points of failure and high computation cost on the user side remain. This study proposes a novel solution named blockchain-based and decentralized attribute-based encryption(BDAE) for data sharing. BDAE enhances traditional scheme by integrating blockchain and distributed key generation technology. The scheme employs an(n, t) threshold secret sharing algorithm, coupled with the Pedersen verifiable secret sharing method, for attribute key generation. This combination ensures key credibility,facilitates joint attribute management, and addresses single bottleneck and key verification issues. Integrated into a blockchain system, the scheme utilizes smart contracts for fine-grained access control and outsourced computing. Blockchain's decentralization and access logs make data sharing tamper-resistant and auditable. Moreover, simulation comparisons demonstrate that the scheme effectively reduces decryption overhead on the user side, meeting practical application requirements.