Search

Federated learning is a new distributed machine learning technology, where training tasks are deployed on user side and training model parameters are sent to the server side. In the whole process, participants do not need to share their own data directly, which greatly avoids privacy issues. However, the trust relationship between mobile users in the learning model has not been established in advance, there is hidden safety when users perform cooperative train with each other. In view of the above problems, a federated learning scheme for mobile network based on reputation evaluation mechanism and blockchain was proposed. The scheme allowed the server side to use subjective logic models to evaluate the reputation of participating mobile users and provided them with credible reputation opinions sharing environment and dynamic access strategy interface based on the technique of smart contract of blockchain. Theoretical and experimental analys is results show that the scheme can enable the server side to select reliable users for training. And it can achieve more fair and effective reputation calculations, which improves the accuracy of federated learning.

To overcome the shortcomings of available forward-secure identity-based signature (IBS) scheme in terms of actual practicability and secret key update efficiency, the notion of identity-based puncturable signature (IBPS) scheme was proposed based on the idea of puncturable public-key encryption scheme. Specifically, the syntax and security notion of IBPS were given, and then a concrete IBPS scheme was constructed based on Bloom filter. Under the computational Diffie-Hellman assumption, the proposed scheme achieved the existential unforgeability in the random oracle model. The performance analysis and implementation results demonstrate that, compared with traditional forward-secure IBS schemes, the proposed scheme provides more practical fine-grained forward secrecy, and has higher efficiency of secret key update. [ABSTRACT FROM AUTHOR]

Data sharing has become a key technology to break down data silos in the big data era. Ciphertext-policy attribute-based encryption (CP-ABE) is widely used in secure data-sharing schemes to realize flexible and fine-grained access control. However, in traditional CP-ABE schemes, the access structure is directly shared along with the ciphertext, potentially leading to users' private information leakage. Outsourcing data to a centralized third party can easily result in privacy leakage and single-point bottlenecks, and the lack of transparency in data storage and sharing casts doubts whether users' data are safe. To address these issues, we propose a blockchain-based CP-ABE scheme with partially hidden access structures (BCP-ABE-PHAS) to achieve fine-grained access control while ensuring user privacy. First, we propose an efficient CP-ABE scheme with partially hidden access structures, where the ciphertext size is constant. To assist data decryption, we design a garbled Bloom filter to help users quickly locate the position of wildcards in the access structure. Then, to improve storage efficiency and system scalability, we propose a data storage scheme that combines blockchain technology and the interplanetary file system, ensuring data integrity. Finally, we employ smart contracts for a transparent data storage and sharing process without third-party participation. Security analysis and performance evaluation show that the proposed BCP-ABE-PHAS scheme can preserve policy privacy with efficient storage and low computational overhead. [ABSTRACT FROM AUTHOR]

In recent years, motivated by the revelation of long-term and widespread surveillance of personal communications, extensive efforts have been putting into store-and-forward asynchronous messaging systems (e.g., email and SMS) for providing critical security guarantees. Of particular interest among them is forward security, which makes past messages remain secure in the event that the secret key gets exposed. Traditional forward-secure public key encryption can provide forward security for asynchronous scenarios, but it is not flexible enough for instant messaging systems. This is mainly because that, after updating his/her secret key, the user totally loses the decryption capacity of ciphertexts that have not been received. In this paper, to achieve practical forward-security of asynchronous messaging systems, we investigate the construction of a new primitive named forward-secure puncturable encryption (FSPE) that captures fine-grained forward security. Namely, the user can maintain the decryption capacity of those encrypted messages that have not been received yet. Meanwhile, even if the secret key is disclosed, those received messages can still remain secure. Specifically, we propose a communication-efficient FSPE scheme for achieving fine-grained forward-secure asynchronous messaging. Moreover, to improve the efficiency of asynchronous messaging built upon FSPE, we extend it to support outsourced decryption. We also implement the proposed scheme and evaluate a proof-of-concept of main algorithms, so as to increase confidence on its correctness and practicability. [ABSTRACT FROM AUTHOR]

Summary: The telecare medicine information system (TMIS) enables patients from different regions to remotely share the same telecare services, which significantly enhances the quality and effectiveness of medical treatment. On the other hand, patients' electronic health records usually involve their privacy information, they thus hesitate to directly transmit these information in TMIS over the public network due to the threat of privacy disclosure. The authenticated key agreement, as a core building of securing communications over the public network, is considered to be necessary for strengthening the security of TMIS. Recently, we note Zhang et al introduced a 3‐factor authenticated key agreement scheme for TMIS and asserted that the proposed scheme can resist various well‐known attacks. Unfortunately, in this paper, we point out that the scheme of Zhang et al cannot achieve the claimed security guarantees. Specifically, their scheme is vulnerable to offline password/identity guessing attack and user/server impersonation attack. To conquer the above security pitfalls, we put forward a new 3‐factor authenticated key agreement scheme with privacy preservation for TMIS. The security evaluation and performance discussion indicate that our scheme can be free from those well‐known and classical attacks including offline guessing attack and impersonation attack, without increasing additional computation cost when compared with related works. Consequently, the new authentication scheme would be more desirable for securing communications in TMIS. [ABSTRACT FROM AUTHOR]

Cloud storage greatly facilitates both individuals and organizations to share data over the Internet. However, there are several security issues that impede to outsource their data. Among various approaches introduced to overcome these issues, attribute-based encryption (ABE) provides secure and flexible access control on shared data, and thus is rather promising. But the original ABE is not adaptable to some special circumstances, where attributes are organized in a hierarchical structure, such as enterprises and official institutions. On the other hand, although the wide use of mobile devices enables users to conveniently access shared data anywhere and anytime, this also increases the risk of key exposure, which will result into unwanted exposure of the shared data. In this paper, we extend the functionality of the original ABE and enhance its security by providing key generation delegation and forward security. Consequently, the enhanced ABE meets applications of large organizations with hierarchies and minimizes the damage in the case of unexpected key exposures. Specifically speaking, we present a forward-secure ciphertext-policy hierarchical attribute-based encryption scheme in prime order bilinear groups, as a core building of attribute-based data sharing scheme. The security of the proposed scheme is proven in the standard model. We conduct experiments to demonstrate its efficiency and practicability. [ABSTRACT FROM AUTHOR]

Constrained spectral clustering (CSC) method can greatly improve the clustering accuracy with the incorporation of constraint information into spectral clustering and thus has been paid academic attention widely. In this paper, we propose a fast CSC algorithm via encoding landmark-based graph construction into a new CSC model and applying random sampling to decrease the data size after spectral embedding. Compared with the original model, the new algorithm has the similar results with the increase of its model size asymptotically; compared with the most efficient CSC algorithm known, the new algorithm runs faster and has a wider range of suitable data sets. Meanwhile, a scalable semisupervised cluster ensemble algorithm is also proposed via the combination of our fast CSC algorithm and dimensionality reduction with random projection in the process of spectral ensemble clustering. We demonstrate by presenting theoretical analysis and empirical results that the new cluster ensemble algorithm has advantages in terms of efficiency and effectiveness. Furthermore, the approximate preservation of random projection in clustering accuracy proved in the stage of consensus clustering is also suitable for the weighted k-means clustering and thus gives the theoretical guarantee to this special kind of k-means clustering where each point has its corresponding weight. [ABSTRACT FROM AUTHOR]

The security of traditional identity-based signature (IBS) is totally built upon the assumption that the private key is absolutely secure. However, with the increasing use of mobile and unprotected devices in today's cryptosystems, the threat of key exposure represents a more serious and realistic concern. To mitigate the damage of key exposure in the setting of IBS, we propose to integrate key evolution and user revocation into IBS, and present forward-secure identity-based signature with user revocation (FS-RIBS). Specifically, we formalize the syntax and security definition of FS-RIBS, and give a concrete construction. The proposed scheme is proven secure in the standard model under aq-type complexity assumption. To demonstrate the merits of our scheme, we theoretically analyse its performance by comparing it with other related works. Moreover, we provide an implementation and the corresponding timing results of our scheme to show its practicability. [ABSTRACT FROM AUTHOR]

In this study, based on attribute and password, we introduce a new kind of two-factor authentication protocol that has various applications such as anonymous authentication and privacy protection. Specifically, our proposal is constructed by introducing password authentication into the generic framework of attribute-based authentication. Consequently, it not only achieves two-factor authentication, but also enjoys the advantages of attribute authentication and password authentication simultaneously. Furthermore, to formally evaluate the security of the proposed protocol, we present the corresponding security model, within which the detailed security proof of the proposal is given. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Because of its positive effects on dealing with the curse of dimensionality in big data, random projection for dimensionality reduction has become a popular method recently. In this paper, an academic analysis of influences of random projection on the variability of data set and the dependence of dimensions has been proposed. Together with the theoretical analysis, a new fuzzy c-means (FCM) clustering algorithm with random projection has been presented. Empirical results verify that the new algorithm not only preserves the accuracy of original FCM clustering, but also is more efficient than original clustering and clustering with singular value decomposition. At the same time, a new cluster ensemble approach based on FCM clustering with random projection is also proposed. The new aggregation method can efficiently compute the spectral embedding of data with cluster centers based representation which scales linearly with data size. Experimental results reveal the efficiency, effectiveness, and robustness of our algorithm compared to the state-of-the-art methods. [ABSTRACT FROM AUTHOR]

The universal serial bus (USB) has some advantages like high transmission speed, plug‐and‐play and hot swapping, and has become the most popular interface standard for peripheral connections. However, such features also make it easier for a malicious user to extract confidential files from computer systems via USB ports. Consequently, to control the potential security risks of USB interface, many workplace and commercial corporations have directly forbidden their employees from using USB devices. To provide a flexible way of using USB without compromising security, this study proposes a novel secure control protocol for USB storage devices. The device and the server are required to complete mutual authentication and establish a session key used to encrypt the transferred files. The details of each phase of the new protocol are given. Security analysis demonstrates that the proposed protocol conquers those security pitfalls existing in the available protocols and can resist various attacks. Performance discussion indicates that the new protocol is also efficient enough for practical applications. [ABSTRACT FROM AUTHOR]

Three-party password-authenticated key exchange (3PAKE) allows two clients, each sharing a password with a trusted server, to establish a session key with the help of the server. It is a quite practical mechanism for establishing secure channels in a large communication network. However, most current 3PAKE protocols are analyzed in security models that do not adequately address protocol composition problem. In this paper, an ideal functionality for 3PAKE within the universal composability framework is defined, which not only provides security guarantees under arbitrary composition with other protocols but also achieves contributiveness and explicit authentication. Moreover, we propose a generic construction of contributory 3PAKE protocol and prove that it securely realizes the ideal functionality in the static corruption model. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT Signcryption can provide confidentiality and authenticity for many cryptographic applications. In this study, we propose a new efficient attribute-based signcryption scheme. This scheme achieves confidentiality against chosen ciphertext attacks and unforgeability against chosen messages attacks in the selective attribute model. In addition, our scheme enjoys traceability by use of non-interactive witness indistinguishable proofs; that is, the authority can break the anonymity of users when necessary. Compared with previous works, our scheme has advantages in terms of functionality and efficiency simultaneously. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The method of incorporating constraint information into spectral clustering, i.e., \constrained spectral clustering (CSC), can greatly improve clustering accuracy, and thus has been widely employed in the machine learning literature. In this paper, we propose a compressed CSC framework by combining specific graph constructions with a recently introduced CSC model. Particularly, our framework has ability to avoid losing the main partition information in the compression process. By presenting a theoretical analysis and empirical results, we demonstrate that our new framework can achieve the same clustering solution as that of the original model with the specific graph structure. In addition, because our framework utilizes landmark-based graph construction and the approximate matrix decomposition simultaneously, it can be applied to both feature and graph data in a more general way. Moreover, the parameter setting in our framework is rather simple, and therefore it is very practical. Experimental results indicate that our framework has advantages in terms of efficiency and effectiveness. [ABSTRACT FROM AUTHOR]