Pseudonym Change Research Articles

Mutual influence of certificate distribution and pseudonym change strategies in vehicular ad-hoc networks

Vehicular ad-hoc networks (VANETs) are subject to high interest from both the automotive industry as well as government bodies owing to their prospect of increasing safety of driving. Wireless data exchange within VANETs requires rigid security mechanisms to enable its usage in safety critical driver assistance systems. Requirements include not only authenticity and integrity of messages, but also privacy of drivers. We find that much research has been conducted on certificate dissemination and on privacy enhancing certificate (i.e., pseudonym) change. However, mutual influence of techniques from both domains has not been studied in prior work. Hence, we provide an analysis of such cross influence. We show that certificate change massively increases channel load under currently standardised certificate distribution mechanisms. Thus, we propose to use explicit signalling of certificate changes among nodes to limit the found overhead. The conducted evaluation shows that this approach overcomes the identified problems.

Mutual influence of certificate distribution and pseudonym change strategies in vehicular ad-hoc networks

Mutual influence of certificate distribution and pseudonym change strategies in vehicular ad-hoc networks

DPMM: dynamic pseudonym-based multiple mix-zones generation for mobile traveler

Road traffic information has become indispensable for routine vehicular communication but user location privacy an important issue which did not well addressed. An adversary may attack a user by tracking location in routine vehicular communication. Although, continuously changing pseudonyms is a promising solution to attain location privacy in road networks, it has been observed that changing pseudonym at improper time or location may again become a threat for location preservation. As a result, a number of techniques for pseudonym-change have been proposed to achieve location privacy on road networks but most of location based services depend upon speed, GPS position and direction angle services. Hence, sensitive information is periodically broadcasted in every 100-300 ms providing an opportunity to adversaries for accessing critical information and easily tracking vehicles. Moreover, existing methods such as RPCLP, EPCS and MODP for attaining location privacy in mix-zones environment have severely suffered due to large number of pseudonym-changes. To cope with these issues, we presented a Dynamic Pseudonym based Multiple Mix-zones (DPMM) strategy to acquire the highest level of accuracy and privacy. The concept of executing dynamic pseudonym change has been forwarded with respect to pseudonyms, velocity and direction of moving objects. We performed our simulations by using one SUMO simulator and analyzed results compared with existing pseudonym-changing techniques. Our simulation results outperformed various existing techniques and provided better results for achieving high privacy rate, requiring small number of pseudonym-change as well as providing best performance.

TAPCS: Traffic-aware pseudonym changing strategy for VANETs

Location privacy is one of the main challenges in Vehicular Ad-hoc Networks (VANETs), since weak protection may hinder the public acceptance of this technology. Frequently changing pseudonyms are commonly accepted as a solution to protect the location privacy in VANETs. However, a simple pseudonym change is not enough to provide the required protection. Although many pseudonym changing strategies have been proposed to enhance the location privacy protection provided by this approach, the development of an effective strategy is not yet achieved. In this paper, we propose a new pseudonym changing strategy called Traffic-Aware Pseudonym Changing Strategy (TAPCS). The aim of this strategy is to provide an effective location privacy protection against the different types of pseudonyms linking attacks that can be performed by a strong passive adversary model. TAPCS is a distributed pseudonym changing strategy and is one of the strategies that use the radio silence technique. Unlike the existing distributed pseudonym changing strategies that use this technique, TAPCS aims to provide a high level of location privacy protection without impacting the safety in the VANETs. The analytical evaluation and simulation results demonstrate the effectiveness of the proposed strategy.

VLPZ: The Vehicular Location Privacy Zone

One of the key challenges in the success of vehicular ad hoc networks (VANETs) is to consider the location privacy of drivers. Although, the pseudonym changing approach is suggested by standardization development organizations such as IEEE and ETSI, the development of an effective pseudonym changing strategy is still an open issue. The existing pseudonym changing strategies are either not effective to protect against the pseudonyms linking attacks or can have a negative impact on the VANETs’ applications. To address these issues, this paper proposes a new pseudonym changing strategy based on the Vehicular Location Privacy Zone (VLPZ), which is a roadside infrastructure designed and dedicated to change the pseudonyms. Existing roadside infrastructures such as gas stations and toll booths are considered as typical places to implement a VLPZ. An analytical model based on queuing theory is developed to evaluate the location privacy protection achieved at a VLPZ using the size of vehicles’ anonymity set as a metric.

MixGroup: Accumulative Pseudonym Exchanging for Location Privacy Enhancement in Vehicular Social Networks

Vehicular social network (VSN) is envisioned to serve as an essential data sensing, exchanging and processing platform for the future Intelligent Transportation Systems. In this paper, we aim to address the location privacy issue in VSNs. In traditional pseudonym-based solutions, the privacy-preserving strength is mainly dependent on the number of vehicles meeting at the same occasion. We notice that an individual vehicle actually has many chances to meet several other vehicles. In most meeting occasions, there are only few vehicles appearing concurrently. Motivated by these observations, we propose a new privacy-preserving scheme, called MixGroup, which is capable of efficiently exploiting the sparse meeting opportunities for pseudonym changing. By integrating the group signature mechanism, MixGroup constructs extended pseudonym-changing regions, in which vehicles are allowed to successively exchange their pseudonyms. As a consequence, for the tracking adversary, the uncertainty of pseudonym mixture is accumulatively enlarged, and therefore location privacy preservation is considerably improved. We carry out simulations to verify the performance of MixGroup. Results indicate that MixGroup significantly outperforms the existing schemes. In addition, MixGroup is able to achieve favorable performance even in low traffic conditions.

An Efficient Profile Matching Protocol Using Privacy Preserving in Mobile Social Network

As we know user profile matching with privacy-preservation in mobile social networks (MSNs) and bring in a family of novel profile matching protocols. We first intend an explicit Comparison-based Profile Matching protocol (eCPM), that runs between parties, initiator, and a responder. It is to propose modified an implicit Comparison-based Profile Matching protocol (iCPM) which allows the initiator to obtain directly some messages instead of the comparison result from the responder. The messages unrelated to user profile can be divided into multiple categories by the responder. The initiator implicitly chooses the open category that is unknown to the responder. The responder prepares two messages in each category, and the initiator can obtain only one message according to the similarity result on a single attribute. Then further, generalize the iCPM to an implicit Predicate-based Profile Matching protocol (iPPM) which allows complex similarity criteria spanning multiple attributes. The secrecy analysis shows all these protocols achieve the privacy of user profiles. Also, the eCPM reveals the similarity result to the initiator, and provides only relative anonymity; the iCPM and the iPPM do not disclose the outcome at all and provide full anonymity (secrecy). It is to analyze the communication overhead and the anonymity strength of the protocols. Then present an enhanced version of the eCPM, called eCPM+, by combining the eCPM with a novel prediction-based adaptive pseudonym change strategy. The performance of the eCPM and the eCPM+ are comparatively studied through extensive trace-based simulations. Simulation results show that the eCPM+ achieves significantly higher anonymity strength with a slightly larger number of pseudonyms than the eCPM.

Motivation for Protecting Selfish Vehicles' Location Privacy in Vehicular Networks

Location privacy is an important issue in vehicular networks since knowledge of a vehicle's location can result in leakage of sensitive information. A way to protect vehicles' location privacy is to have them change their pseudonyms in predetermined regions known as mix zones. However, selfish vehicles may not change their pseudonyms because of limited resources (such as pseudonyms and bandwidth). This could jeopardize the location privacy of those vehicles that are in need of changing their pseudonyms. To encourage vehicles to cooperate in changing their pseudonyms, we propose a method called Motivation for Protecting Selfish Vehicles' Location Privacy (MPSVLP). In MPSVLP, vehicles can form a mix zone dynamically when their pseudonyms are close to expiration and can also earn reputation “credit” by implementing a pseudonym change. The simulations show that MPSVLP motivates more selfish vehicles to cooperate with each other while maintaining a high level of location privacy. In addition, MPSVLP can reduce communication overhead in comparison with the existing methods.

Pseudonyms in IPv6 ITS Communications: Use of Pseudonyms, Performance Degradation, and Optimal Pseudonym Change

IPv6 developed as a next generation Internet protocol will provide us with safer and more efficient driving environments as well as convenient and infotainment features in cooperative intelligent transportation systems (ITS). In this paper, we introduce the use of pseudonyms in IPv6 ITS communications for preserving location privacy. We conduct qualitative study on the performance degradation due to the use of pseudonyms and quantitative analysis on the optimal pseudonym change interval. Numerical results demonstrate that an appropriate pseudonym change interval should be changed depending on the packet arrival rate, mobility rate, and security level.

Enhancing privacy in collaborative traffic‐monitoring systems using autonomous location update

Collaborative traffic-monitoring (CTM) systems exploit the location information continuously collected from vehicles. Location data are very sensitive information that made privacy a major obstacle for the widespread usage of CTM systems. The way how this data are generated and used is very important for users' privacy and data quality as well. Recently, two CTM approaches have been proposed, the first relies on a dedicated infrastructure that is called vehicular ad hoc networks (VANETs), and the second utilises the existing underlying infrastructure such as cellular and wireless networks. In this study, the authors propose a privacy aware collaborative traffic monitoring system (PA-CTM) that considers the privacy and security properties of VANETs and existing infrastructures. PA-CTM provides a client server architecture that relies on existing infrastructures and enhances privacy by: (i) Using a robust pseudonym providing system for anonymous access. Pseudonyms enable users to be authenticated anonymously by the traffic server without having their identities revealed. It also allows revealing identities for law enforcement purposes when necessary. Users are able to change their pseudonyms and hence hide their complete trajectory information form traffic server. (ii) Utilising a novel autonomous location update mechanism (ALUM) that does not rely on a trusted third party and uses only local parameters (speed and direction) for triggering a location update or pseudonym change. These performance results showed that ALUM is effective for traffic monitoring in terms of both privacy and utility.

MixZone in Motion: Achieving Dynamically Cooperative Location Privacy Protection in Delay-Tolerant Networks

Delay-tolerant networks (DTNs) are typically sparse ad hoc networks where node density is low and contacts between nodes in the network do not occur very frequently. The existing location privacy protection methods, which require mobile nodes to collectively change their pseudonyms in special regions called mix zones, may not work well in DTNs due to their unique characteristics, including low network density and limited contact duration. In this paper, we propose a novel cooperative location privacy protection scheme, which is called AVATAR, for sparse DTNs. The main idea of AVATAR is to generate a certain number of virtual nodes in the proximity of a node and allow both virtual and real nodes to make a coordinated pseudonym change in an enlarged region, which are named virtual mix zones. Each AVATAR participant benefits from increased location privacy protection at the cost of generating a series of signed position messages, which are named footprint signatures. To stimulate each node to contribute more footprint signatures to the virtual mix zones, AVATAR proposes a reward mechanism, which is modeled as a multiunit discriminatory auction game. Extensive simulations and analysis have been provided to demonstrate the effectiveness and efficiency of the proposed scheme.

Fully Anonymous Profile Matching in Mobile Social Networks

In this paper, we study user profile matching with privacy-preservation in mobile social networks (MSNs) and introduce a family of novel profile matching protocols. We first propose an explicit Comparison-based Profile Matching protocol (eCPM) which runs between two parties, an initiator and a responder. The eCPM enables the initiator to obtain the comparison-based matching result about a specified attribute in their profiles, while preventing their attribute values from disclosure. We then propose an implicit Comparison-based Profile Matching protocol (iCPM) which allows the initiator to directly obtain some messages instead of the comparison result from the responder. The messages unrelated to user profile can be divided into multiple categories by the responder. The initiator implicitly chooses the interested category which is unknown to the responder. Two messages in each category are prepared by the responder, and only one message can be obtained by the initiator according to the comparison result on a single attribute. We further generalize the iCPM to an implicit Predicate-based Profile Matching protocol (iPPM) which allows complex comparison criteria spanning multiple attributes. The anonymity analysis shows all these protocols achieve the confidentiality of user profiles. In addition, the eCPM reveals the comparison result to the initiator and provides only conditional anonymity; the iCPM and the iPPM do not reveal the result at all and provide full anonymity. We analyze the communication overhead and the anonymity strength of the protocols. We then present an enhanced version of the eCPM, called eCPM+, by combining the eCPM with a novel prediction-based adaptive pseudonym change strategy. The performance of the eCPM and the eCPM+ are comparatively studied through extensive trace-based simulations. Simulation results demonstrate that the eCPM+ achieves significantly higher anonymity strength with slightly larger number of pseudonyms than the eCPM.

Automated buyer profiling control based on human privacy attitudes

In e-commerce applications, vendors can construct detailed profiles about customers’ preferences, which is known as buyer profiling. These profiles can then be used by vendors in order to perform practices such as price discrimination, poor judgment, etc. The use of pseudonyms and, specially, changing pseudonyms from time to time are known to minimize profiling, minimizing the capacity of vendors to perform such practices in turn. Although there are some frameworks and tools that support pseudonym change, there are few proposals that suggest or directly change the pseudonym in an automated fashion. Instead, users are usually provided with the mechanisms to change pseudonyms but without any advise on when they should actually use these mechanisms. In this paper, we present an approach to control buyer profiling by means of automated pseudonym changes performed according to human privacy attitudes. We also present an application scenario and an evaluation of our proposal.

Cooperative pseudonym change scheme based on the number of neighbors in VANETs

In Vehicular Ad hoc NETworks (VANETs), trigger-based pseudonym change schemes play an important role in providing anonymity. However, the anonymity provided by these schemes usually is low mainly because the behavior of changing pseudonym is individual. Considering cooperation on changing pseudonym can enhance anonymity, in this paper, we give a general cooperation framework. As an application of the framework, we present a Cooperative Pseudonym change scheme based on the number of Neighbors (CPN). We generally analyze the anonymity provided by the CPN scheme and qualitatively compare the scheme with its corresponding scheme without cooperation, Non-CPN (NCPN). Then, under uniform traffic distribution, we develop an approximate analytical model for CPN in relatively simple one-lane VANETs to analyze the anonymity. Finally, we investigate the anonymity of CPN in one-lane and multi-lane VANETs by simulation. The results show that the ratio of the size of anonymity set in multi-lane to that in one-lane VANETs, first quickly goes up, then slowly decreases a bit, and at last approaches the value of number of lanes. In addition, the improved performance of CPN over NCPN reaches peak when the average number of neighbors approaches that number in the trigger.

An analytical model for random pseudonym change scheme in VANETs

The emerging Vehicular Ad hoc NETworks (VANETs) can improve safety, efficiency and convenience in transportation. In spite of the expected benefits, VANETs also introduce some location privacy risk by periodically broadcasting vehicular information. Pseudonym change is commonly accepted as one approach to protect location privacy in VANETs, but the effectiveness of most pseudonym change schemes has never been investigated theoretically. In this paper, focusing on the Random Pseudonym Change (RPC) scheme, we propose an analytical model to quantify its level of location privacy by calculating the size of anonymity set of a vehicle. With this model, we can analyze the probability of a vehicle changing pseudonym simultaneously with its neighbor, which can be then used to calculate the size of anonymity set of the vehicle. Further, we investigate the influence of the pseudonym lifetime distribution on the level of location privacy. Research results, which are validated via extensive simulations, show that for the RPC scheme, the uniform pseudonym lifetime distribution can provide better location privacy protection than the reciprocal pseudonym lifetime distribution. In addition, we also discuss the conditional probability of a vehicle changing pseudonym simultaneously with its neighbor given the age of pseudonym used by the neighbor at the time when the vehicle last changed pseudonym, and point out that utilizing the age of pseudonym can improve the level of location privacy.

Pseudonym Changing at Social Spots: An Effective Strategy for Location Privacy in VANETs

As a prime target of the quality of privacy in vehicular ad hoc networks (VANETs), location privacy is imperative for VANETs to fully flourish. Although frequent pseudonym changing provides a promising solution for location privacy in VANETs, if the pseudonyms are changed in an improper time or location, such a solution may become invalid. To cope with the issue, in this paper, we present an effective pseudonym changing at social spots (PCS) strategy to achieve the provable location privacy. In particular, we first introduce the social spots where several vehicles may gather, e.g., a road intersection when the traffic light turns red or a free parking lot near a shopping mall. By taking the anonymity set size as the location privacy metric, we then develop two anonymity set analytic models to quantitatively investigate the location privacy that is achieved by the PCS strategy. In addition, we use game-theoretic techniques to prove the feasibility of the PCS strategy in practice. Extensive performance evaluations are conducted to demonstrate that better location privacy can be achieved when a vehicle changes its pseudonyms at some highly social spots and that the proposed PCS strategy can assist vehicles to intelligently change their pseudonyms at the right moment and place.

Plagiarism or Pseudonym Change? A Review on Divans of Zihnî and Zîver

Plagiarism or Pseudonym Change? A Review on Divans of Zihnî and Zîver