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Security is an indispensable part of smart grid (SG). Key establishment protocols play a vital role in fulfilling the security requirements in SG. In recent years, many key establishment schemes have been proposed for SG. However, only three of them offer the strong smart meter anonymity. In 2015, Tsai and Lo presented an anonymous key establishment scheme to be employed in SG. Recently, Odelu et al. have demonstrated that Tsai and Lo's scheme suffers from the ephemeral secret leakage attack. Furthermore, another scheme has been proposed recently by He et al. that has improved the efficiency of Tsai and Lo's scheme. However, besides its merits, we indicate that He et al.'s scheme suffers from both known session-specific temporary information attack and private key leakage. Additionally, these three anonymous schemes have the key escrow problem since the trusted anchor is aware of entities’ private key. Hence, to cover the existing issues, in this paper we propose a key establishment scheme that not only is free from the security challenges of the previous anonymous schemes and key escrow problem, but also is efficient in terms of both computational and communication costs. Finally, yet importantly, we present the performance analysis of our proposed scheme on a state-of-the-art advanced RISC machine (ARM) chip, namely NXP LPC1788, as a suitable hardware for the smart meters. [ABSTRACT FROM AUTHOR]

Cloning attacks seriously impede the security of radio-frequency identification (RFID) applications. This paper tackles deterministic clone detection for anonymous RFID systems without tag identifiers (IDs) as a priori. Existing clone detection protocols either cannot apply to anonymous RFID systems due to necessitating the knowledge of tag IDs or achieve only probabilistic detection with a few clones tolerated. This paper proposes three protocols—BASE, DeClone, and DeClone+—toward fast and deterministic clone detection for large anonymous RFID systems. BASE leverages the observation that clone tags make tag cardinality exceed ID cardinality. DeClone is built on a recent finding that clone tags cause collisions that are hardly reconciled through rearbitration. For DeClone to achieve detection certainty, this paper designs breadth first tree traversal toward quickly verifying unreconciled collisions and hence the cloning attack. DeClone+ further incorporates optimization techniques that promise faster clone detection when clone ratio is relatively high. The performance of the proposed protocols is validated through analysis and simulation. This paper also suggests feasible extensions to enrich their applicability to distributed design. [ABSTRACT FROM PUBLISHER]

Sensor communication in the smart home environment is still in its infancy as the information exchange between sensors is vulnerable to security threats. Many traditional solutions use single-layer or multi-layer (i.e., onion routing protocol) encryption/decryption algorithms. But, in the traditional onion routing protocol, if the directory server is compromised, it may not track the malicious onion nodes within the onion network. It questioned the path anonymity of the onion routing protocol. Motivated by this, we proposed a blockchain and onion routing (OR)-based secure and trusted framework in the paper. The anonymity of the proposed OR network is maintained by storing and tracking the onion nodes threshold values through the blockchain network. A long short-term memory (LSTM) model is also utilized to classify the sensors data requests as malicious and non-malicious. The performance of the proposed system is evaluated with different performance metrics such as F1 score and accuracy. The LSTM model significantly improves the initial detection rate of malicious data requests from smart home sensors. Over these benefits, we considered the entire communication via 6G channel, reducing the overall communication latency. Additionally, the OR network is simulated over the shadow simulator to analyze the OR network’s performance considering parameters such as packet delivery ratio and malicious onion node detection rate. [ABSTRACT FROM AUTHOR]

Central banks and governments all over the world are increasingly exploring digital versions of fiat money, known as retail Central Bank Digital Currencies (CBDCs). Most initiatives rely on Distributed Ledger Technologies and are presented as alternatives to physical cash. Consequently, anonymity-related regulatory questions have naturally started to arise in terms of Anti-Money Laundering and Counter-Terrorist Financing compliance. Against this backdrop, this paper provides a techno-legal taxonomy of approaches to balance privacy and transparency in CBDCs without thwarting accountability, but it also underlines cross-sectoral impacts. The contribution heeds regulation-by-design as its core methodological foundation, with Privacy-Enhancing Technologies as the relevant use case. Thus, it highlights that not only technology aids legal purposes, but also that some regulatory requirements ought to be designed into technology for one to reach agreed-upon results and/or standards. [ABSTRACT FROM AUTHOR]

The Internet of Things (IoT) is a wide network consisting of Internet-connected objects using installed software, such as home appliances, vehicles, and other entities embedded with sensors, actuators, radio-frequency identification (RFID), and electronics to exchange data. In the last two decades, numerous IoT solutions have been developed by small, medium-sized, and large enterprises to make our lives easier. Furthermore, private and academic researchers have extensively investigated some practical IoT solutions. The rapid expansion of IoT solutions accompanies numerous security concerns because the underlying IoT protocols and communication technologies have not considered security. Recently, blockchain has emerged to become one of the promising technologies that might overcome some of the IoT limitations (security limitations, in particular). Blockchain technology is a database ledger that uses a peer-to-peer (P2P) network and stores transactions and asset registries. Blockchain can be described as a mounting list of records (i.e., blocks) with the following properties: distributed, decentralized, immutable, and shared. This paper surveyed recent security advances to overcome IoT limitations using blockchain. In this article, the blockchain attempts to overcome IoT limitations that are related to cyber security have been classified into four categories: end-to-end traceability; data privacy and anonymity; identity verification and authentication; and confidentiality, data integrity, and availability (CIA). Intended as a guideline for future research, this paper also explores systematic processes. [ABSTRACT FROM AUTHOR]

In this paper we are concerned with geolocating the anonymous crowds of Dark Web forums. We do not focus on single users, but on the crowd as a whole. We work in two directions: The first idea is to exploit the time of all posts in the Dark Web forums to build profiles of the visiting crowds and to match the crowd profiles to that of users from known regions. Then, we develop a new dataset to detect the native language of the crowds to support and integrate this match. We assess the effectiveness of our methodology on the standard web and two Dark Web forums with users of known origin, and apply it to three controversial anonymous Dark Web forums. We believe that this work helps the community better understand the Dark Web from a sociological point of view and supports the investigation of authorities when the security of citizens is at stake. [ABSTRACT FROM AUTHOR]

For 35 years, the cryptographic community has created the impression that anonymous communication is always possible. Chaum’s dining cryptographer’s solution is regarded as achieving unconditional security. Chaum’s MIX approach, namely, applying a uniformly random permutation on the plaintexts to be sent, is often given as a definition for anonymity. However, people working in law enforcement know that attempts by whistle-blowers and criminals to remain at large, often fail. The content of the message may reveal the name of the sender or may leak for whom the message is really intended. To understand this issue, we give a definition of perfect anonymity. We contrast our definition with Chaum’s approach and discuss the impact on Chaum’s dining cryptographer’s solution. [ABSTRACT FROM AUTHOR]

In the era of e-Health, privacy protection has become imperative in applications that carry personal and sensitive data. Departing from the data-perturbation based privacy-preserving techniques that reduce the fidelity of the disclosed data, in this paper we investigate anonymous communications, which mask the identity of the data sender while providing high data reliability. Focusing on the physical (PHY) layer, we first explore the break of privacy through a statistical attribute based sender detection (SD) from the receiver. Compared to the existing literature, this enables a much enhanced SD performance, especially when the users are equipped with different numbers of antennas. To counteract the advanced SD approach above, we formulate explicit anonymity constraints for the design of the anonymous precoder, which mask the sender’s PHY attributes that can be exploited by SD, while at the same time preserving the reliability of the data. Then, anonymity entropy-oriented precoders are proposed for different antenna configurations at the users, which adaptively construct a maximum number of aliases while obeying users’ signal-to-noise-ratio requirements for data accuracy. Simulation results demonstrate that the proposed anonymous precoders provide the highest level of anonymity entropy over the benchmarks, while achieving reasonable symbol error rate for the communication signal. [ABSTRACT FROM AUTHOR]

Recent advances in information and communication technologies and embedded systems have given rise to a new disruptive technology, the Internet of Things (IoTs). IoT allows people and objects in the physical world as well as data and virtual environments to interact with each other so as to create smart environments, such as smart transport systems, smart cities, smart health, and so on. However, IoT raises some important questions and also introduces new challenges for the security of systems and processes and the privacy of individuals, such as their location and movements and so on. In this paper, at first, we propose a distributed IoT system architecture. Subsequently, we propose an anonymous authentication scheme, which can ensure some of the notable properties, such as sensor anonymity, sensor untraceability, resistance to replay attacks, cloning attacks, and so on. It is argued that the proposed authentication scheme will be useful in many distributed IoT applications (such as radio-frequency identification-based IoT system, Biosensor-based IoT healthcare system, and so on), where the privacy of the sensor movement is greatly desirable. [ABSTRACT FROM PUBLISHER]

Remote data access control is of crucial importance in public cloud. Based on its own inclinations, the data owner predefines the access policy. When the user satisfies the data owner's access policy, it has the right to access the data owner's remote data. In order to improve flexibility and efficiency of remote data access control, attribute-based encryption (for short, ABE) is used to realize the remote data fine-grained access control. For the low-capacity terminals, verifiable outsourced decryption is a very attractive technique. In the real application scenarios, the user's attributes are usually managed by many authorities. When some authorized users access some sensitive remote data, they hope to preserve their identity privacy. From the two points, we propose an anonymous distributed fine-grained access control protocol with verifiable outsourced decryption in public cloud (for short, VOD-ADAC). VOD-ADAC is a novel concept which is proposed for the first time in the paper. By adopting the pseudonym technique, the user's high anonymity can be achieved by frequently changing the independent pseudonyms at some highly social spots. This paper formalizes the system model and security model of VOD-ADAC protocol. Then, by using hybrid encryption technique of distributed ABE and symmetric encryption, a concrete VOD-ADAC protocol is designed from the bilinear pairings. Through security analysis and performance analysis, our proposed VOD-ADAC protocol is provably secure and efficient. [ABSTRACT FROM AUTHOR]

In a smart grid, fine-grained usage reports of consumers are gathered using some computationally constrained smart measurement devices. One of the most challenging requirements in the data aggregation is how to securely read the consumption data, while putting the least possible overhead on smart meters. For this reason, recently, two efficient security protocols have been proposed to be used for subsequent secure consumption reports gathered from isolated smart measurement devices. Nonetheless, in both protocols, for each key establishment, the smart reader requires to connect to the electricity service provider (ESP) via the Internet. This paper proposes a novel key establishment protocol, which is free from the ESP involvement during the key agreement and benefits from notable reduction in the communication cost. Our thorough efficiency and security analyses indicate the eminence of the proposed security protocol. [ABSTRACT FROM AUTHOR]

Cyber physical systems which integrate physical system dynamics with digital cyber infrastructure are envisioned to transform our core infrastructural frameworks, such as the smart electricity grid, transportation networks, and advanced manufacturing. This integration, however, exposes the physical system functioning to the security vulnerabilities of cyber communication. Both scientific studies and real-world examples have demonstrated the impact of data injection attacks on complex systems, including the Internet, the smart electricity grid, and air traffic systems. In this paper, an abstract theoretical framework is proposed to study data injection/modification attacks on Markov modeled dynamical systems from the perspective of an adversary. Typical data injection attacks focus on one shot attacks by adversary and the non-detectability of such attacks under static assumptions. In this paper, we study dynamic data injection attacks where the adversary is capable of modifying a temporal sequence of data and the physical controller is equipped with prior statistical knowledge about the data arrival process to detect the presence of an adversary. The goal of the adversary is to modify the arrivals to minimize a utility function of the controller while minimizing the detectability of his presence as measured by the K–L divergence between the prior and posterior distribution of the arriving data. The tradeoff between these two metrics—controller utility and the detectability cost—is studied analytically for different underlying dynamics. The proposed framework is then applied to a practical problem in data networks where a router tries to hide the path of traffic flow from timing analysis by an active adversary who can modify the timing of an incoming packet stream. This problem is studied from the adversary perspective wherein the goal is to balance two costs—the adversary’s detectability cost measured by the K–L divergence and the network privacy cost measured by the maximum length of the packet stream whose paths can be hidden by a memory limited router. [ABSTRACT FROM PUBLISHER]

In this paper, we propose an efficient and anonymous authentication protocol with a succinct multi-subscription credential (AnMsc) in Space-air-ground integrated vehicular networks (SAGVN). First, we adopt a subscription-based service model in SAGVN. Specifically, vehicular users (VEs) can subscribe to network services and conduct direct mutual authentication with subscribed access points (APs) to avoid message exchanges with VEs’ home network. Early application data can also be transmitted with authentication messages to improve communication efficiency. Second, we carefully tailor the design of the redactable signature and propose an efficient credential management mechanism in SAGVN. Multiple service subscriptions can be embedded into a succinct (constant-size) credential. With the credential, VEs can anonymously access any subscribed AP without revealing other subscription information. Thorough security analysis and comprehensive performance evaluation demonstrate that AnMsc can guarantee key-exchange security, VE anonymity, and service fairness while ensuring credential management and authentication efficiency. [ABSTRACT FROM AUTHOR]

As mobile devices ownership becomes more prevalent (e.g., a user owns multiple mobile devices), the capability to offer secure and user friendly authentication becomes increasingly important. A large number of identity-based user authentication mechanisms for the wireless mobile environment have been proposed. However, they are not generally designed for situations where a user’s private key and some other sensitive data can be exposed if his/her mobile device is remotely or physically controlled by an attacker. Threshold secret sharing is one of the solutions to this problem, but it is limited in the requirement that there should exist an honest third-party to hold the complete key after the secret reconstruction process. Therefore, in this paper, we consider the special case that only two devices (i.e., no honest party) at the user’s side jointly perform user authentication with a server, and neither device can successfully complete the authentication process alone. Moreover, the key reconstruction is not needed during authentication so that neither device can hold a complete key. We then analyze the security of the proposed protocol and show that it satisfies all known security requirements in practical applications, particularly the key exposure attack resistance. The performance analysis of the proposed protocol is also presented to demonstrate its practicality. [ABSTRACT FROM AUTHOR]

Fairness among multiple users sharing a common resource is an important criterion in the design and evaluation of scheduling algorithms in networks. Anonymous networking, where sources of transmitted packets are undecipherable to an eavesdropper, requires packets arriving at routers from multiple sources to be randomly reordered prior to transmission, which works against the notion of temporal fairness in packet scheduling. Consequently, it is important to understand the relationship between temporal fairness and achievable anonymity. In this paper, this relationship is investigated for three fair scheduling paradigms: First-Come–First-Serve (FCFS), Fair Queuing, and the Proportional Method. Using an information-theoretic metric for anonymity and a common temporal fairness index that measures the degree of out-of-order transmissions, the anonymity achievable under these scheduling paradigms is characterized and their anonymity-fairness tradeoffs are compared. The FCFS and Fair Queuing algorithms have little inherent anonymity, and a significant improvement in anonymity is achieved by relaxing their respective fairness paradigms. The analysis of the relaxed FCFS criterion, in particular, is accomplished by modeling the problem as a stochastic control system that is solved using dynamic programming. The proportional method of scheduling, while unpopular in networks today, is shown to outperform the other fair scheduling algorithms when trading temporal fairness for anonymity, and is also proven to be asymptotically optimal as the buffer size of the scheduler is increased. [ABSTRACT FROM AUTHOR]

The need of secure big data storage service is more desirable than ever to date. The basic requirement of the service is to guarantee the confidentiality of the data. However, the anonymity of the service clients, one of the most essential aspects of privacy, should be considered simultaneously. Moreover, the service also should provide practical and fine-grained encrypted data sharing such that a data owner is allowed to share a ciphertext of data among others under some specified conditions. This paper, for the first time, proposes a privacy-preserving ciphertext multi-sharing mechanism to achieve the above properties. It combines the merits of proxy re-encryption with anonymous technique in which a ciphertext can be securely and conditionally shared multiple times without leaking both the knowledge of underlying message and the identity information of ciphertext senders/recipients. Furthermore, this paper shows that the new primitive is secure against chosen-ciphertext attacks in the standard model. [ABSTRACT FROM PUBLISHER]

In smart grid, key exchange protocols play a vital role in providing secure channels to read consumption reports from the smart meters. Thus far, several key exchange schemes have been proposed for the networked smart meters. However, for the first time, quite recently, Shaet al. have presented an interesting two-phase authentication and key agreement scheme that exclusively aims at the isolated smart meters. In their scheme, they have properly addressed the computationally constrained smart meters by offering a lightweight key exchange protocol. Nevertheless, after meticulous observation, we found that their proposed scheme cannot resist the desynchronization attack and cannot provide the perfect forward secrecy. Moreover, there are some other weaknesses in their scheme. As a result, to tackle the existing security challenges, in this paper, by utilization of the extended Chebyshev chaotic maps, we propose an efficient anonymous password-authenticated key exchange protocol that not only is free from the limitations of Shaet al.'s scheme, but also provides the anonymity. The security analysis in the random oracle model and using the widely accepted ProVerif tool besides the computational and communication costs comparison demonstrate that the proposed scheme has reached a proper level of efficiency without sacrificing the desired security properties. [ABSTRACT FROM AUTHOR]

Vehicular ad-hoc networks (VANETs) have been researched with regard to enhance driver’s safety and comfort. In VANETs, all vehicles share their status and road conditions with neighboring nodes by periodically generating safety messages. To provide reliable VANET services, message authentication is an important feature. In particular, anonymous message authentication has attracted considerable interest, because periodic broadcast messages from a vehicle can be used to track its location. Unfortunately, previously proposed anonymous message authentication protocols had serious practical shortcomings, including high communication, authentication, and revocation costs, as well as reliability issues. Thus, in this paper, we propose an anonymous authentication protocol based on a cooperative authentication method. The proposed method does not require mode synchronization between cooperative and non-cooperative authentication. In addition, we design a two-layer pseudo-identity generation method and construct a key update tree for efficient revocation. Simulations show that our protocol does not result in packet losses caused by authentication overheads, even when the vehicle density is 200/km2. [ABSTRACT FROM PUBLISHER]

With the rapid growth of application migration, the anonymity in data center networks becomes important in breaking attack chains and guaranteeing user privacy. However, existing anonymity systems are designed for the Internet environment, which suffer from high computational and network resource consumption and deliver low performance, thus failing to be directly deployed in data centers. In order to address this problem, this paper proposes an efficient and easily deployed anonymity scheme for software defined networking-based data centers, called mimic channel (MIC). The main idea behind MIC is to conceal the communication participants by modifying the source/destination addresses, such as media access control (MAC) and Internet protocol (IP) address at switch nodes, so as to achieve anonymity. Compared with the traditional overlay-based approaches, our in-network scheme has shorter transmission paths and less intermediate operations, thus achieving higher performance with less overhead. We also propose a collision avoidance mechanism to ensure the correctness of routing, and three mechanisms to enhance the traffic-analysis resistance. To enhance the practicality, we further propose solutions to enable MIC co-existing with some MIC-incompatible systems, such as packet analysis systems, intrusion detection systems, and firewall systems. Our security analysis demonstrates that MIC ensures unlinkability and improves traffic-analysis resistance. Our experiments show that MIC has extremely low overhead compared with the base-line transmission control protocol (TCP) (or secure sockets layer (SSL)), e.g., less than 1% overhead in terms of throughput. Experiments on MIC-based distributed file system show the applicability and efficiency of MIC. [ABSTRACT FROM PUBLISHER]

In crowdsourcing database, human operators are embedded into the database engine and collaborate with other conventional database operators to process the queries. Each human operator publishes small HITs (Human Intelligent Task) to the crowdsourcing platform, which consists of a set of database records and corresponding questions for human workers. The human workers complete the HITs and return the results to the crowdsourcing database for further processing. In practice, published records in HITs may contain sensitive attributes, probably causing privacy leakage so that malicious workers could link them with other public databases to reveal individual private information. Conventional privacy protection techniques, such as K-Anonymity, can be applied to partially solve the problem. However, after generalizing the data, the result of standard K-Anonymity algorithms may render uncontrollable information loss and affects the accuracy of crowdsourcing. In this paper, we first study the tradeoff between the privacy and accuracy for the human operator within data anonymization process. A probability model is proposed to estimate the lower bound and upper bound of the accuracy for general K-Anonymity approaches. We show that searching the optimal anonymity approach is NP-Hard and only heuristic approach is available. The second contribution of the paper is a general feedback-based K-Anonymity scheme. In our scheme, synthetic samples are published to the human workers, the results of which are used to guide the selection on anonymity strategies. We apply the scheme on Mondrian algorithm by adaptively cutting the dimensions based on our feedback results on the synthetic samples. We evaluate the performance of the feedback-based approach on U.S. census dataset, and show that given a predefined \(K\) , our proposal outperforms standard K-Anonymity approaches on retaining the effectiveness of crowdsourcing. [ABSTRACT FROM AUTHOR]

Maximizing data usage and minimizing privacy risk are two conflicting goals. Organizations always apply a set of transformations on their data before releasing it. While determining the best set of transformations has been the focus of extensive work in the database community, most of this work suffered from one or both of the following major problems: scalability and privacy guarantee. Differential Privacy provides a theoretical formulation for privacy that ensures that the system essentially behaves the same way regardless of whether any individual is included in the database. In this paper, we address both scalability and privacy risk of data anonymization. We propose a scalable algorithm that meets differential privacy when applying a specific random sampling. The contribution of the paper is two-fold: 1) we propose a personalized anonymization technique based on an aggregate formulation and prove that it can be implemented in polynomial time; and 2) we show that combining the proposed aggregate formulation with specific sampling gives an anonymization algorithm that satisfies differential privacy. Our results rely heavily on exploring the supermodularity properties of the risk function, which allow us to employ techniques from convex optimization. Through experimental studies we compare our proposed algorithm with other anonymization schemes in terms of both time and privacy risk. [ABSTRACT FROM PUBLISHER]

Access control mechanisms protect sensitive information from unauthorized users. However, when sensitive information is shared and a Privacy Protection Mechanism (PPM) is not in place, an authorized user can still compromise the privacy of a person leading to identity disclosure. A PPM can use suppression and generalization of relational data to anonymize and satisfy privacy requirements, e.g., k-anonymity and l-diversity, against identity and attribute disclosure. However, privacy is achieved at the cost of precision of authorized information. In this paper, we propose an accuracy-constrained privacy-preserving access control framework. The access control policies define selection predicates available to roles while the privacy requirement is to satisfy the k-anonymity or l-diversity. An additional constraint that needs to be satisfied by the PPM is the imprecision bound for each selection predicate. The techniques for workload-aware anonymization for selection predicates have been discussed in the literature. However, to the best of our knowledge, the problem of satisfying the accuracy constraints for multiple roles has not been studied before. In our formulation of the aforementioned problem, we propose heuristics for anonymization algorithms and show empirically that the proposed approach satisfies imprecision bounds for more permissions and has lower total imprecision than the current state of the art. [ABSTRACT FROM AUTHOR]

In the near future, mobile payment systems based on smartphones are expected to be widely applied in various environments, including transit services. When passengers use mass transit, their private information, such as their identity and route, may be made available to some related organizations, such as transit agencies, financial institutions, mobile carriers, and providers of smart cards, among others, even when the passengers may not want their information to be revealed. To protect passenger privacy, this paper proposes a privacy-preserving transit payment system based on traceable signatures, identity-based signatures, and anonymous signatures. In addition to passenger privacy, the proposed system facilitates the proactive blocking of misbehaving passengers, free-transfer services (or transfer discount), and postpaid programs. We demonstrate that the performance of this system is good enough for immediate deployment based on various experiments. [ABSTRACT FROM PUBLISHER]

In mobile opportunistic social networks (MOSNs), mobile devices carried by people communicate with each other directly when they meet for proximity-based MOSN services (e.g., file sharing) without the support of infrastructures. In current methods, when nodes meet, they simply communicate with their real IDs, which leads to privacy and security concerns. Anonymizing real IDs among neighbor nodes solves such concerns. However, this prevents nodes from collecting real ID-based encountering information, which is needed to support MOSN services. Therefore, in this paper, we propose FaceChange that can support both anonymizing real IDs among neighbor nodes and collecting real ID-based encountering information. For node anonymity, two encountering nodes communicate anonymously. Only when the two nodes disconnect with each other, each node forwards an encrypted encountering evidence to the encountered node to enable encountering information collection. A set of novel schemes are designed to ensure the confidentiality and uniqueness of encountering evidences. FaceChange also supports fine-grained control over what information is shared with the encountered node based on attribute similarity (i.e., trust), which is calculated without disclosing attributes. Advanced extensions for sharing real IDs between mutually trusted nodes and more efficient encountering evidence collection are also proposed. Extensive analysis and experiments show the effectiveness of FaceChange on protecting node privacy and meanwhile supporting the encountering information collection in MOSNs. Implementation on smartphones also demonstrates its energy efficiency. [ABSTRACT FROM AUTHOR]

Wireless sensor networks (WSNs) include spatially allotted autonomous instruments that employ sensors to check environmental or physical conditions. These autonomous instruments or nodes blend with routers or gateway to make several WSN-based real-time applications. In many critical applications, an external user can directly access the real-time data from sensor node. In this context, before offering access, the legitimacy of the user is required to be verified through a secure authentication scheme. Since, in WSN-based real-time applications, the privacy of the user is greatly important, the authentication scheme for such environment should be anonymous. Till now, impressive efforts have been made in designing lightweight anonymous authentication protocol for WSN-based real-time applications. However, most of such protocols are vulnerable to DoS attacks, which are occurred due to the loss of synchronization between the participants. Furthermore, to rebuilt synchronization between the participants, a protocol may need to compromise un-link-ability property. Therefore, it can be argued that the problem of DoS attack has not been addressed properly in the existing literatures. In this paper, we present a way to deal with DoS attacks in designing lightweight anonymous authentication protocol for WSN-based real-time applications without compromising any anonymity support. We argue that our proposed solution can easily be incorporated with the existing schemes to be resilient to DoS attacks. [ABSTRACT FROM PUBLISHER]

Current implementations of high-latency anonymous communication systems are based on pool mixes. These tools act as routers that apply a random delay to the messages traversing them, making it hard for an eavesdropper to guess the correspondences between incoming and outgoing messages. This hides the identities of communicating partners in the network, but it does not prevent an adversary continuously monitoring the network from unveiling the communication profiles of the users. In this paper, we tackle the problem of designing the delay characteristic of pool mixes so as to maximize the protection of the users against profiling attacks. First, we propose a theoretical model for users’ sending behavior which we validate using three real data sets of a different nature. Then, we use this model to perform a privacy analysis of the system and obtain the delay function of the mix, which is optimal in the sense of protecting the users. Since computing the delay characteristic of this optimal pool mix requires information about the users’ behavior, we also propose a user-independent but less effective mix design. We evaluate these pool mixes, comparing them with one of the most studied existing designs, the binomial pool mix. Our experiments show that an adversary against our optimal design may need up to 30 times as long to achieve the same level of disclosure as for a binomial pool mix. [ABSTRACT FROM PUBLISHER]

Anonymous communication has become a hot research topic in order to meet the increasing demand for web privacy protection. However, there are few such systems which can provide high level anonymity for web browsing. The reason is the current dominant dummy packet padding method for anonymization against traffic analysis attacks. This method inherits huge delay and bandwidth waste, which inhibits its use for web browsing. In this paper, we propose a predicted packet padding strategy to replace the dummy packet padding method for anonymous web browsing systems. The proposed strategy mitigates delay and bandwidth waste significantly on average. We formulated the traffic analysis attack and defense problem, and defined a metric, cost coefficient of anonymization (CCA), to measure the performance of anonymization. We thoroughly analyzed the problem with the characteristics of web browsing and concluded that the proposed strategy is better than the current dummy packet padding strategy in theory. We have conducted extensive experiments on two real world data sets, and the results confirmed the advantage of the proposed method. [ABSTRACT FROM PUBLISHER]

Mashup is a web technology that allows different service providers to flexibly integrate their expertise and to deliver highly customizable services to their customers. Data mashup is a special type of mashup application that aims at integrating data from multiple data providers depending on the user's request. However, integrating data from multiple sources brings about three challenges: 1) Simply joining multiple private data sets together would reveal the sensitive information to the other data providers. 2) The integrated (mashup) data could potentially sharpen the identification of individuals and, therefore, reveal their person-specific sensitive information that was not available before the mashup. 3) The mashup data from multiple sources often contain many data attributes. When enforcing a traditional privacy model, such as K-anonymity, the high-dimensional data would suffer from the problem known as the curse of high dimensionality, resulting in useless data for further data analysis. In this paper, we study and resolve a privacy problem in a real-life mashup application for the online advertising industry in social networks, and propose a service-oriented architecture along with a privacy-preserving data mashup algorithm to address the aforementioned challenges. Experiments on real-life data suggest that our proposed architecture and algorithm is effective for simultaneously preserving both privacy and information utility on the mashup data. To the best of our knowledge, this is the first work that integrates high-dimensional data for mashup service. [ABSTRACT FROM PUBLISHER]

In this paper, we address attacks that exploit the timing behavior of TCP and other protocols and applications in low-latency anonymity networks. Mixes have been used in many anonymous communication systems and are supposed to provide countermeasures to defeat traffic analysis attacks. In this paper, we focus on a particular class of traffic analysis attacks, flowcorrelation attacks, by which an adversary attempts to analyze the network traffic and correlate the traffic of a flow over an input link with that over an output link. Two classes of correlation methods are considered, namely time-domain methods and frequency-domain methods. Based on our threat model and known strategies in existing mix networks, we perform extensive experiments to analyze the performance of mixes. We find that all but a few batching strategies fail against flow-correlation attacks, allowing the adversary to either identify ingress and egress points of a flow or to reconstruct the path used by the flow. Counter intuitively, some batching strategies are actually detrimental against attacks. The empirical results provided in this paper give an indication to designers of Mix networks about appropriate configurations and mechanisms to be used to counter flow-correlation attacks. [ABSTRACT FROM AUTHOR]

By exploiting a smart card, this paper presents a robust and efficient password-authenticated key agreement scheme. This paper strengthens the security of the scheme by addressing untraceability property such that any third party over the communication channel cannot tell whether or not he has seen the same (unknown) smart card twice through the authentication sessions. The proposed remedy also prevents a kind of denial of service attack found in the original scheme. High performance and other good functionalities are preserved. [ABSTRACT FROM AUTHOR]

This paper presents and analyzes a method for enhancing the privacy of vehicles that use the public-key infrastructure (PKI) to secure communications. In particular, it examines the privacy limitations of a PKI system, where certificates are shared among multiple vehicles using a combinatorial certificate scheme. Such a system was implemented in the U.S. Vehicle Infrastructure Integration (VII) proof-of-concept trial to secure vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication and preserve vehicle privacy. The analysis shows that, in low vehicle densities, there is a high probability that a vehicle may have a locally unique certificate that is not shared by other vehicles. Vehicles using unique certificates may be vulnerable to being tracked or identified. This paper proposes a vehicle-based certificate selection method for enhancing the privacy of vehicle communications. In our method, a vehicle monitors the certificates in use by neighboring vehicles and identifies those certificates that it also possesses. The vehicle then selects a certificate already in use to secure its own communication. This allows a vehicle to "blend in" to its environment but without substantially increasing an attacker's ability to evade exposure. We provide an analysis of I he anonymity and unlinkability properties of the method and demonstrate that it rapidly reduces the number of vehicles using unique certificates to increase privacy. [ABSTRACT FROM AUTHOR]

Based on identity-based cryptography, this paper proposes a remote authentication protocol featured with client anonymity, nonrepudiation, and improved efficiency for value-added services in a mobile environment. First, an identity-based signature scheme is proposed, and the verification result of the signature is a constant with respect to the signer's identifier. Then, a remote authentication protocol is constructed by combining the proposed signature scheme with a new concept called the client account index, which helps to realize client anonymity with no encryption operations. A formal proof and a theoretical analysis are provided to show the security strength of the proposals. Performance evaluation shows that compared with previous identity-based remote authentication schemes, the new protocol reduces at least 21.7% of the overall running time with stronger security; the reductions in the overall running time and signaling traffic reach 31.9% and 82.0%, respectively, compared with previous Rivest-Shamir-Adleman-based schemes. [ABSTRACT FROM AUTHOR]

Vehicular ad hoc networks (VANETs) are a particular subclass of mobile ad hoc networks that raise a number of security challenges, notably from the way users authenticate the network. Authentication technologies based on existing security policies and access control rules in such networks assume full trust on roadside unit (RSU) and authentication servers. The disclosure of authentication parameters enables user’s traceability over the network. VANETs’ trusted entities (e.g., RSU) can utilize such information to track a user traveling behavior, violating user privacy and anonymity. In this paper, we proposed a novel, light-weight, adaptive group-based zero knowledge proof-authentication protocol (AGZKP-AP) for VANETs. The proposed authentication protocol is capable of offering various levels of users’ privacy settings based on the type of services available on such networks. Our scheme is based on the zero-knowledge-proof crypto approach with the support of tradeoff options. Users have the option to make critical decisions on the level of privacy and the amount of resources usage they prefer such as short system response time versus the number of private information disclosures. Furthermore, AGZKP-AP is incorporated with a distributed privilege control and revoking mechanism that render user’s private information to law enforcement in case of a traffic violation. [ABSTRACT FROM AUTHOR]

In a paper recently published in the IEEE TRANSACTIONS ON CONSUMER ELECTRONICS, Zhu and Ma proposed a new authentication scheme with anonymity for wireless environments. However, this paper shows that Zhu and Ma's scheme has some security weaknesses. Therefore, in this paper, a slight modification to their scheme is proposed to improve their shortcomings. As a result, the scheme proposed in this paper can enhance the security of Zhu and Ma's scheme. Finally, the performance of this scheme is analyzed. Compared with the Zhu-Ma scheme, this scheme is also simple and efficient. [ABSTRACT FROM AUTHOR]

Electronic health systems, such as telecare medical information system (TMIS), allow patients to exchange their health information with a medical center/doctor for diagnosis in real time, and across borders. Given the sensitive nature of health information/medical data, ensuring the security of such systems is crucial. In this paper, we revisit Das et al.'s authentication protocol, which is designed to ensure patient anonymity and untraceability. Then, we demonstrate that the security claims are invalid, by showing how both security features (i.e., patient anonymity and untraceability) can be compromised. We also demonstrate that the protocol suffers from smartcard launch attacks. To mitigate such design flaws, we propose a new lightweight authentication protocol using the cryptographic hash function for TMIS. We then analyze the security of the proposed protocol using AVISPA and Scyther, two widely used formal specification tools. The performance analysis demonstrates that our protocol is more efficient than other competing protocols. [ABSTRACT FROM AUTHOR]

In this paper, we introduce an attribute-based framework to achieve secure communications in vehicular ad hoc networks (VANETs), which enjoys several advantageous features. The proposed framework employs attribute-based signature (ABS) to achieve message authentication and integrity and protect vehicle privacy, which greatly mitigates the overhead caused by pseudonym/private key change or update in the existing solutions for VANETs based on symmetric key, asymmetric key, and identity-based cryptography and group signature. In addition, we extend a standard ABS scheme with traceability and revocation mechanisms and seamlessly integrate them into the proposed framework to support vehicle traceability and revocation by a trusted authority, and thus, the resulting scheme for vehicular communications does not suffer from the anonymity misuse issue, which has been a challenge for anonymous credential-based vehicular protocols. Finally, we implement the proposed ABS scheme using a rapid prototyping tool called Charm to evaluate its performance. [ABSTRACT FROM AUTHOR]

Collections of real-world data usually have implicit or explicit structural relations. For example, databases link records through foreign keys, and XML documents express associations between different values through syntax. Privacy preservation, until now, has focused either on data with a very simple structure, e.g. relational tables, or on data with very complex structure e.g. social network graphs, but has ignored intermediate cases, which are the most frequent in practice. In this work, we focus on tree structured data. Such data stem from various applications, even when the structure is not directly reflected in the syntax, e.g. XML documents. A characteristic case is a database where information about a single person is scattered amongst different tables that are associated through foreign keys. The paper defines k^(m,n) -anonymity, which provides protection against identity disclosure and proposes a greedy anonymization heuristic that is able to sanitize large datasets. The algorithm and the quality of the anonymization are evaluated experimentally. [ABSTRACT FROM PUBLISHER]

To ensure the security and privacy of the patient’s health status in the wireless body area networks (WBANs), it is critical to secure the extra-body communication between the smart portable device held by the WBAN client and the application providers, such as the hospital, physician or medical staff. Based on certificateless cryptography, this paper proposes a remote authentication protocol featured with nonrepudiation, client anonymity, key escrow resistance, and revocability for extra-body communication in the WBANs. First, we present a certificateless encryption scheme and a certificateless signature scheme with efficient revocation against short-term key exposure, which we believe are of independent interest. Then, a certificateless anonymous remote authentication with revocation is constructed by incorporating the proposed encryption scheme and signature scheme. Our revocation mechanism is highly scalable, which is especially suitable for the large-scale WBANs, in the sense that the key-update overhead on the side of trusted party increased logarithmically in the number of users. As far as we know, this is the first time considering the revocation functionality of anonymous remote authentication for the WBANs. Both theoretic analysis and experimental simulations show that the proposed authentication protocol is provably secure in the random oracle model and highly practical. [ABSTRACT FROM PUBLISHER]

Anonymous communication, where users communicate without revealing the identities of communicating parties or the paths of data flow is critical in data networks. On the Internet, Chaum mixes, intermediate nodes, or proxy servers, which use layered encryption and packet shuffling methods to hide source identities, are used to provide anonymity to network users. In this paper, an information theoretic framework is developed to study the maximum anonymity achievable by packet shuffling when the mixes are memory limited—in other words, they can store a finite number of packets. Using the Shannon entropy of the a posteriori distribution of packet sources from an eavesdropper’s perspective as the measure of anonymity, the maximum achievable anonymity of a single mix with buffer size b (packets) serving two independent Poisson sources with equal arrival rates is shown to be \log \big [2\cos \big (\frac {\pi }{b+3}\big )\big ] . For a general multiuser system, the maximum anonymity as buffer size b\rightarrow \infty is shown to approach the entropy of the source arrival probabilities at a convergence rate no lesser than 1/b^2 . When the arrival probabilities of the general multiuser system can be expressed as a rational fraction k/2^n for some fixed $n$ , this convergence rate is shown to be achievable. The anonymity analysis is extended to a general network of mixes connecting the sources to a common destination, where the source anonymity achievable on the destination link is shown to be lower bounded by a weighted sum of the anonymity achievable by each individual mix. [ABSTRACT FROM AUTHOR]

Existing anonymous remote authentication protocols to secure wireless body area networks (WBANs) raise challenges such as eliminating the need for distributing clients’ account information to the application providers and achieving forward security. This paper efficiently addresses these challenges by devising a scalable certificateless remote authentication protocol with anonymity and forward security for WBANs. Different from the previous protocols in this field, our protocol not only provides mutual authentication, session key establishment, anonymity, unlinkability, and nonrepudiation, but also achieves forward security, key escrow resilience, and scalability. Performance evaluation demonstrates that compared with the most efficient ID-based remote anonymous authentication protocol, our protocol reduces at least 52.6% and 17.6% of the overall running time and communication overhead, respectively, and the reduction in the computation cost and communication overhead achieves at least 73.8% and 55.8%, respectively, compared with up-to-date certificateless remote authentication protocol with anonymity. [ABSTRACT FROM PUBLISHER]