Proof of Retrievability (POR) is an important cryptographic primitive that has attracted considerable attention in the research community for its ability to enable users to audit the integrity of outsourced files on cloud servers without retrieving them. A POR scheme with public verifiability further enhances usability by allowing users to delegate the auditing task to a third party, making it highly desirable for a wide range of applications. However, most existing publicly verifiable POR schemes derive their security from the computational hardness of discrete logarithm or factoring, making them vulnerable to quantum attacks. Although it is possible to construct quantum-resistant POR schemes with public verifiability upon hash trees or general lattices, the resulting schemes often exhibit performance limitations when compared to existing constructions, thereby limiting their deployment in real-world applications. In this work, we address this gap by constructing a publicly verifiable POR scheme on structured lattices. We show that our scheme is provably secure in the random oracle model under the Ring-LWE and Ring-SIS assumptions. We provide an implementation of our scheme and the experimental results show that its performance is comparable to certain well-known constructions based on traditional assumptions.

Cloud storage is a significant service provided by the cloud that enables users to store their immense data into the cloud. As the advent of the big data era, cloud storage services are becoming increasingly popular. For security reasons, data owners would like to check the integrity of their data after storing it in the cloud. To do this, they usually make use of the public cloud data integrity checking schemes. This paper focuses on user anonymity in such schemes so that no third party could infer the identity information of any data owner from checking procedures. The problem is obviously inevitable in reality, however the current solutions are relatively involved as they heavily use public key certificates and/or incur huge communication overhead. In this paper we introduce the concept of attribute-based cloud data integrity checking to achieve user anonymity lightly and present security models for such systems. We also provide a practical construction and prove its security in the random oracle model. Finally, we show how to extend our construction to protect data privacy against any third party.

Software-defined networking (SDN) has become a popular paradigm for managing large-scale networks including cloud servers and data centers because of its advantages of centralized management and programmability. The issues of scalability and reliability that a single centralized controller suffers makes distributed controller architectures emerge. One key limitation of distributed controllers is the statically configured switch-controller mapping, easily causing uneven load distribution among controllers. Previous works have proposed load-balancing methods with switch migration to address this issue. However, the higher-load controller is always directly considered as the overloaded controller that need to shift its load to other controllers, even if it has no response time delay. The pursuit of absolute load-balancing effect can also result in frequent network delays and service interruptions. Additionally, if there are several overloaded controllers, just one controller with the maximum load can be addressed within a single load-balancing operation, reducing load-balancing efficiency. To address these problems, we propose SMCLBRT, a load-balancing strategy of multiple SDN controllers based on response time, considering the changing features of real-time response times versus controller loads. By selecting the appropriate response time threshold and dealing with multiple overloading controllers simultaneously, it can well solve load-balancing problem in SDN control plane with multiple overloaded controllers. Simulation experiments exhibit the effectiveness of our scheme.

The recent proliferation of human-carried mobile devices has given rise to the mobile crowd sensing (MCS) systems. However, the sensory data provided by the participating workers are usually not reliable. As an efficient technique to extract truthful information from unreliable data, truth discovery has drawn significant attention. Currently, the privacy concern of the participating workers poses a major challenge on the design of truth discovery mechanisms. Although the existing mechanism can conduct truth discovery with high accuracy and strong privacy guarantee, tremendous overhead is incurred on the worker side. In this paper, we propose a novel lightweight privacy preserving truth discovery framework, L-PPTD, which is implemented by involving two non-colluding cloud platforms and adopting additively homomorphic cryptosystem. This framework not only achieves the protection of each worker's sensory data and reliability information but also introduces little overhead to the workers. In order to further reduce each worker's overhead in the scenarios where only the sensory data need to be protected, we propose another more lightweight framework named L2-PPTD. The desirable performance of the proposed frameworks is verified through extensive experiments conducted on real world MCS systems.

Identity-based signature is an important technique for light-weight authentication. Recently, many efforts have been made to construct identity-based signatures over lattice assumptions since they would remain secure in future quantum age. In this paper we present a new identity-based signature scheme from lattice problems. This scheme is more efficient than other lattice-based identity-based signature schemes in terms of both computation and communication complexities. We prove its security in the random oracle model under short integer solution assumption that is as hard as approximating several worst-case lattice problems. We also extend the scheme to an identity-based message recovery signature scheme that has better performance.

Histogram estimation is one of the fundamental tasks in crowdsourcing data aggregation. Since contributing data reveal more or less information about individuals' identifications and activities, participants need to preserve privacy of data according to their own levels of privacy concern. However, most of the existing work only aggregates data with an identical privacy level. In this paper, we propose an aggregation scheme for histogram estimation, wherein participants can publish their data at personalized differential-privacy levels. The aggregator also benefits from potential wider engagement or more honest data. Specially, since privacy levels under personalized privacy policy are sensitive information for participants, our scheme permits participants to keep their privacy levels secret even from the aggregator. We also show how to further optimize the estimation accuracy under given privacy levels by choosing specific randomization strategies.

Abstract Certificateless signature and certificate‐based signature are two attractive replacements of regular signature and identity‐based signature because they can alleviate the vexing certificate management problem in regular signatures and can also eliminate the inherent key escrow problem in identity‐based signatures. Although a number of certificateless signatures and certificate‐based signatures from bilinear pairings have been proposed, their lattice‐based counterparts still remain unrealized. In this paper, we present the first constructions of certificateless signature and certificate‐based signature from lattices. Both constructions are proven to be secure in the random oracle model under conventional small integer solution assumption that is as hard as approximating several standard lattice problems. Copyright © 2014 John Wiley & Sons, Ltd.

Truthful spectrum auctions have been extensively studied in recent years. Truthfulness makes bidders bid their true valuations, simplifying greatly the analysis of auctions. However, revealing one's true valuation causes severe privacy disclosure to the auctioneer and other bidders. To make things worse, previous work on secure spectrum auctions does not provide adequate security. In this paper, based on TRUST, we propose PS-TRUST, a provably secure solution for truthful double spectrum auctions. Besides maintaining the properties of truthfulness and special spectrum reuse of TRUST, PS-TRUST achieves provable security against semi-honest adversaries in the sense of cryptography. Specifically, PS-TRUST reveals nothing about the bids to anyone in the auction, except the auction result. To the best of our knowledge, PS-TRUST is the first provably secure solution for spectrum auctions. Furthermore, experimental results show that the computation and communication overhead of PS-TRUST is modest, and its practical applications are feasible.

Certificateless cryptography is a new type of public key cryptography, which removes the certificate management problem in traditional public key cryptography and the key escrow problem in identity-based public key cryptography. Multi-proxy signature is an extension of proxy signature, which allows an original signer authorizing a group of proxy signers and only the cooperation of all proxy signers in the group can create valid proxy signatures on behalf of the original signer. Recently, Jin and Wen combined certificateless cryptography with multi-proxy signature, and proposed a model as well as a concrete scheme of certificateless multi-proxy signature. They claimed that their scheme is provably secure in their security model. Unfortunately, in this paper by giving two attacks, we will show that their certificateless multi-proxy signature scheme can be broken. The first attack indicates their security model is flawed and the second attack indicates their certificateless multi-proxy signature scheme is insecure. Possible improvements are also suggested to prevent these attacks.

ABSTRACT In this paper, we propose a novel distributed covert channel in HTTP. Different from traditional covert channels in HTTP, the channel deploys multiple HTTP clients to dilute steganographic features. In a proper multiple‐to‐multiple transmission model based on the modulation of URLs, the channel is efficient and reliable. With a Poisson request generator, simulating behaviors of normal HTTP visitors, the covert traffic has a legitimate HTTP appearance that helps it be undetectable. The transmission experiments prove that the channel is error free and has a high transmission rate. The results of the undetectability experiment show that the channel is adjustable. By adjusting a certain parameter, the channel can trade off two different features, the transmission rate and the undetectability, which can meet different demands in practical applications. Copyright © 2013 John Wiley & Sons, Ltd.