Blockchain-Based Decentralized Public Auditing for Cloud Storage

With the increasing popularity of cloud storage systems, users often outsource their data to the cloud. Cloud-servers provide storage space at a low cost and reduce the burden of the users. Once the users outsource data to the cloud, they lose control over their data. Hence, the integrity of outsourced data is the main challenge. To address this issue, many public auditing schemes were proposed, based on third-party auditors (TPA). However, traditional public auditing schemes are vulnerable to malicious TPA who may not provide correct auditing results on time. To resist malicious TPA, blockchain-based public auditing schemes have been proposed recently. Although, blockchain-based auditing schemes avoid malicious auditors, they are suffering from the key escrow problem, because their design is based on identity-based signatures. To overcome the key escrow problem and malicious auditors, in this paper, we propose a Blockchain based Certificateless Public Auditing scheme for cloud storage systems. In security analysis, we prove that the proposed scheme is secure against the type I/II/III/IV adversaries. In experimental analysis, we show that the proposed scheme outperforms than existing schemes.

In real-world scenarios, in order to encourage one to report others crimes, judicial department usually rents independent cloud storage spaces to receive the precious evidences from whistleblowers. Since the uploaded data are not controlled by cloud users, remote data integrity is very important. Public cloud auditing enables an auditor to periodically check the integrity of outsourcing data on behalf of users, without retrieving the entire data file. However, most existing data auditing schemes have potential security vulnerabilities, and thus cannot defense many security attacks (e.g., the man-in-the-middle attack). Meanwhile, it is significant to protect whistleblower’s identity privacy, reward the real data uploader, and further trace the responsibility of slanders accurately. From the aforementioned requirements, we present an efficient blockchain-assisted conditional anonymity privacy-preserving public auditing (BA-CAPPPA) scheme with reward mechanism. The Ethereum blockchain is integrated into BA-CAPPPA to enhance the security level of the whole public auditing mechanism. Theoretical analysis results show that the BA-CAPPPA achieves man-in-the-middle attack resistance, storage correctness guarantee, data privacy-preservation, conditional identity anonymity, and reward mechanism. Performance evaluations and comparisons demonstrate that BA-CAPPPA could outperform some state-of-the-art data auditing schemes.

Wireless body area networks (WBANs) consist of many small low-power sensors, through which users could monitor the real-time parameters of patients' physiology remotely. This capability could improve medical care and the monitoring of patients. WBAN devices typically have limited computing, storage, power, and communication capabilities. These limitations restrict the applications that WBANs can support. To enhance the capabilities of WBANs, the concept of cloud-assisted WBANs has been introduced recently. By using cloud computing technologies, cloud-assisted WBANs can provide more efficient processing of patients' physiology parameters and support richer services. In cloud-assisted WBANs, the data of patients' physiology are stored in the cloud. The integrity of the data is very important because these data will be used to provide a medical diagnosis and other medical treatments. To address the issue of integrity in cloud-assisted WBANs, we propose an efficient certificateless public auditing (CLPA) scheme. A security analysis of our proposed CLPA scheme shows that it is provably secure against two types of adversaries (i.e., a type-I adversary can replace users' public keys, and a type-II adversary can access the master key) in an environment of certificateless cryptography. A detailed performance analysis demonstrates that the proposed CLPA scheme yields better performance over a previously proposed CLPA scheme.

In cloud storage, the most common concerns for users are data integrity, confidentiality and availability. Recently, many data integrity auditing schemes have been proposed, some of which achieved privacy-preserving public auditing, some of which realised data sharing and group dynamic, and some of which supported data dynamic. However, as far as we know, there does not exist a practical auditing scheme which can simultaneously realise all the functions mentioned above; In addition, all the existing schemes adopt the method of computing message authentication code (MAC) by users to achieve the following data integrity auditing, nevertheless, it is a arduous task to compute MACs for these cloud users with constrained computing and storage capabilities. In this paper, we propose a novel privacy-preserving public auditing scheme for shared data in the cloud, which can also support data dynamic operation and group dynamic. First, we bring proxy signature into the existing auditing scheme. The cloud user can delegate the computation of MACs to a cloud computing server, so that the user's burden would be greatly reduced; second, by introducing a Lagrange interpolating polynomial, our scheme realises the identity privacy-preserving in the precondition of almost no addition of any new computation and less storage space, moreover it makes group dynamic simple; third, we make an index-switch table and combine it with the Merkle hash tree to realise the practical and secure dynamic operations of shared data by group users; fourth, in our scheme, the cloud storage server will add its private key in producing the proof information to protect the data privacy and resist the active attack. Theoretical analysis demonstrates our scheme is provably secure.

With the rapid development of cloud storage and cloud computing technology, users can upload data to the cloud and share it with other users. However, the integrity and the privacy of data files at the cloud service provider suffer from challenges. In order to protect the data of user in the cloud, particularly for user groups without honest managers and semitrusted third-party auditors, we construct a new public auditing scheme that integrates a (t,n) threshold signature, an incentive mechanism, an identity-based designated verifier group, blinding technology, and a multiblock signature technique. In our scheme, the (t,n) threshold signature can eliminate the single power of the user group’s managers, to ensure that members of the user group take part in data sharing fairly and equally. The generation of a user’s key pairs and the signatures of data can be encouraged by an incentive mechanism based on a blockchain. Moreover, we introduce an identity-based designated verifier group and blinding technology to preserve data privacy during the data integrity auditing process. Furthermore, the multiblock signature technique reduces the costs to sign data blocks and verify. Finally, the security analysis and performance analysis demonstrate that our scheme is provably reliable and efficient.

In recent years, real-world attacks against PKI take place frequently. For example, malicious domains' certificates issued by compromised CAs are widespread, and revoked certificates are still trusted by clients. In spite of a lot of research to improve the security of SSL/TLS connections, there are still some problems unsolved. On one hand, although log-based schemes provided certificate audit service to quickly detect CAs' misbehavior, the security and data consistency of log servers are ignored. On the other hand, revoked certificates checking is neglected due to the incomplete, insecure and inefficient certificate revocation mechanisms. Further, existing revoked certificates checking schemes are centralized which would bring safety bottlenecks. In this paper, we propose a blockchain-based public and efficient audit scheme for TLS connections, which is called Certchain. Specially, we propose a dependability-rank based consensus protocol in our blockchain system and a new data structure to support certificate forward traceability. Furthermore, we present a method that utilizes dual counting bloom filter (DCBF) with eliminating false positives to achieve economic space and efficient query for certificate revocation checking. The security analysis and experimental results demonstrate that CertChain is suitable in practice with moderate overhead.

Data storage is an important application of cloud computing, where clients can remotely store their data into the cloud. By uploading their data into the cloud, clients can be relieved from the burden of local data storage and maintenance. This new paradigm of data storage service also introduces new security challenges. One of these risks that can attack the cloud computing is the integrity of the data stored in the cloud. In order to overcome the threat of integrity of data, the client must be able to use the assistance of a Third Party Auditor (TPA), in such a way that the TPA verifies the integrity of data stored in cloud with the client's public key on the behalf of the client. The existing schemes with single verifier (TPA) may not scale well for this purpose. In this paper, we propose An Efficient Distributed Verification Protocol (EDVP) to verify the integrity of data in a distributed manner with support of multiple verifiers (Multiple TPAs) instead of single Verifier (TPA). Through the extensive security, performance and experimental results, we show that our scheme is more efficient than single verifier based scheme.

Public auditing and data deduplication are integral considerations in providing efficient and secure cloud storage services. Nevertheless, the traditional data deduplication models that support public auditing can endure the enormous waste of storage and computation resources induced through data redundancy and repeated audit work by multiple tenants on trusted third-party auditor (TPA). In this work, we introduce blockchain-based secure decentralized public auditing in a decentralized cloud storage with an efficient deduplication model. We employ blockchain to take on the task of centralized TPA, which also mitigates the implications of malicious blockchain miners by using the concept of a decentralized autonomous organization (DAO). Specifically, we employ the idea of redactability for blockchain to handle often neglected security issues that would adversely affect the integrity of stored auditing records on blockchain in decentralized auditing models. However, the proposed model also employs an efficient deduplication scheme to attain adequate storage savings while preserving the users from data loss due to duplicate faking attacks. Moreover, the detailed concrete security analysis demonstrates the computational infeasibility of the proposed model against proof-of-ownership, duplicate faking attack (DFA), collusion attack, storage free-riding attack, data privacy, and forgery attack with high efficiency. Finally, the comprehensive performance analysis shows the scalability and feasibility of the proposed model.

Public auditing for cloud storage is of critical importance as the users relies on semi-trusted cloud storage service for data sharing which does not guarantee/assure the integrity of the data being stored. With public auditing of clouds, users resort to a third party auditor (TPA) who verify and assure the internal consistency/lack of corruption of their data in cloud storage services. Despite the good work previously done by researchers in auditing while preserving privacy, still available mechanisms do not efficiently conceal users' privacy from TPA during sharing of data and yet supporting data and group dynamics. In this paper, we propose privacypreserving auditing scheme that exploits the ring signature to calculate verifications needed to audit data integrity.In this proposed approach, the identities of the user are kept private from public verifier and dynamic groups are supported -that is a new user can be added into the group and an existing group member can be revoked during data sharing.

The emergence of Wireless Body Area Networks (WBAN) provides users with ubiquitous wireless communication services, such as continuous exchange of medical information in real time. Therefore, WBAN is considered to be one of the effective wireless sensor technologies for improving medical services. However, the characteristics of WBAN make it subject to multiple attacks, such as the leakage of private information of users, and WBAN is also inefficient. In this paper, a certificateless ring signature scheme CLRS is proposed. In addition, we propose a public auditing scheme with identity privacy protection, which combines the certificateless ring signature technology for cloud-assisted body area network. Through the analysis of security, it shows that the scheme can resist the existing attack methods such as forging attacks. Finally, the comparison between theoretical analysis and experimental simulation shows that the scheme has obvious efficiency advantages compared with the existing scheme.

Cloud storage is a mode of online storage in which data are stored on multiple virtual servers usually hosted by third parties. Cloud service providers manage and operate data storage as services. The major concern in cloud storage is the integrity of outsourced data. Many public auditing schemes which authorize the third party auditor (TPA) to check the integrity of outsourced data have been proposed. However, most of them are based on traditional public key cryptosystems. This paper proposes an efficient certificateless public auditing Scheme (CL‐PAS) in cloud storage. In the process of challenge and auditing, CL‐PAS ensures that malicious cloud servers cannot forge auditing evidences to deceive TPA to pass the verification, and prevents curious TPA from recovering original data from auditing evidences. So it strengthens privacy preserving. Security analysis shows that CL‐PAS scheme meets the predetermined security requirements. The simulation and performance analysis results show that, compared with similar schemes, CL‐PAS scheme has the higher efficiency.

Data outsourcing through cloud storage enables the users to share on-demand resources with cost effective IT services but several security issues arise like confidentiality, integrity and authentication. Each of them plays an important role in the successful achievement of the other. In cloud computing data integrity assurance is one of the major challenges because the user has no control over the security mechanism to protect the data. Data integrity insures that data received are the same as data stored. It is a result of data security but data integrity refers to validity and accuracy of data rather than protect the data. Data security refers to protection of data against unauthorized access, modification or corruption and it is necessary to ensure data integrity. This paper proposed a new approach using Matrix Dialing Method in block level to enhance the performance of both data integrity and data security without using Third Party Auditor (TPA). In this approach, the data are partitioned into number of blocks and each block converted into a square matrix. Determinant factor of each matrix is generated dynamically to ensure data integrity. This model also implements a combination of AES algorithm and SHA-1 algorithm for digital signature generation. Data coloring on digital signature is applied to ensure data security with better performance. The performance analysis using cloud simulator shows that the proposed scheme is highly efficient and secure as it overcomes the limitations of previous approaches of data security using encryption and decryption algorithms and data integrity assurance using TPA due to server computation time and accuracy.

Cloud storage relieves the user from the local management of software and hardware by enabling high quality on demand storage services to store their data in remote locations. Storing the data in remote locations not only reduces the management overheads but also eliminates the user’s physical control over data storage and data security. The loss of physical control over data brings out various security issues such as data loss, tampering of data, data modification. The primary issue is to ensure the correctness of data stored in remote locations which can be resolved by enabling public auditing for cloud storage services. In public auditing, not only the user but anyone can verify the data correctness. The introduction of third-party auditor, who works on behalf of cloud user to verify data integrity helps to reduce user computation resources and cost. The key prerequisite for the public auditing protocol is to support dynamic data operations as data in cloud are dynamic in nature. Cloud is a multiuser environment, so the auditing protocol must scale well to handle multiple auditing processes simultaneously. This paper aims at an extensive survey which mainly outlines the requirements for cloud public auditability and compares varied public auditing protocols.

A secure and scalable data integrity auditing scheme based on hyperledger fabric

The remote data integrity auditing technology can guarantee the integrity of outsourced data in clouds. Users can periodically run an integrity auditing protocol by interacting with cloud server, to verify the latest status of outsourced data. Integrity auditing requires user to take massive time-consuming computations, which would not be affordable by weak devices. In this paper, we propose a privacy-preserving TPA-aided remote data integrity auditing scheme based on Li et al.’s data integrity auditing scheme without bilinear pairings, where a third party auditor (TPA) is employed to perform integrity auditing on outsourced data for users. The privacy of outsourced data can be guaranteed against TPA in the sense that TPA could not infer its contents from the returned proofs in the integrity auditing phase. Our construction is as efficient as Li et al.’s scheme, that is, each procedure takes the same time-consuming operations in both schemes, and our solution does not increase the sizes of processed data, challenge and proof.