Group Signature with relaxed-privacy and revocability for VANET

This paper adapts a new group signature (GS) scheme to the specific needs of certain application e.g., a vehicular adhoc network (VANET). Groth GS is the first efficient GS scheme in the BSZ-model with security proofs in the standard model. We modify the Groth GS in order to meet a restricted, but arguably sufficient set of privacy proper-ties. Although there are some authentication schemes using GS none of them satisfy all the desirable security and privacy properties. Either they follow GSs that rely on Random Oracle Model, or unable to satisfy potential application requirements. In particular, link management which allows any designated entities to link messages, whether they are coming from the same member or a certain group of members without revealing their identities; opening soundness that prevents malicious accusations by the opener against some honest member of the group; revocation system that privileges from fraudulent member like the traditional Public Key infrastructure (PKI). In order to achieve the aforementioned security properties together, we propose a new GS model where linkability, sound opening and revocability properties are assembled in a single scheme. The novelty of our proposal stems from extending the Groth GS by relaxing strong privacy properties to a scheme with a lightly lesser privacy in order to fit an existing VANET application requirements. In addition, we partially minimize the Groth GS scheme to expedite efficiency

MLAS: Multiple level authentication scheme for VANETs

The vehicular ad hoc network (VANET) is an emerging type of network which enables vehicles on roads to inter-communicate for driving safety. The basic idea is to allow arbitrary vehicles to broadcast ad hoc messages (e.g. traffic accidents) to other vehicles. However, this raises the concern of security and privacy. Messages should be signed and verified before they are trusted while the real identity of vehicles should not be revealed, but traceable by authorized party. Existing solutions either rely too heavily on a tamper-proof hardware device, or do not have an effective message verification scheme. In this paper, we propose a multiple level authentication scheme which still makes use of tamper-proof devices but the strong assumption that a long-term system master secret is preloaded into all tamper-proof devices is removed. Instead the master secret can be updated if needed to increase the security level. On the other hand, messages sent by vehicles are classified into two types - regular messages and urgent messages. Regular messages can be verified by neighboring vehicles by means of Hash-based Message Authentication Code (HMAC) while urgent messages can only be verified with the aid of RSUs nearby by means of a conditional privacy-preserving authentication scheme. Copyright 2011 ACM.postprintThe 6th ACM Symposium on Information, Computer and Communications Security (ASIACCS 2011), Hong Kong, China, 22-24 March 2011. In Proceedings of 6th ACM ASIACCS, 2011, p. 471-47

OPQ: OT-based private querying in VANETs

We consider the querying service (e.g., location-based query service) in vehicular ad hoc networks (VANETs). Querying service has been studied in various kinds of networks such as traditional mobile phone networks and other mobile ad hoc networks. However, existing schemes are either not suitable for VANETs due to their highly dynamic environment or do not provide a privacy-preserving solution. In this paper, we first discuss the security concerns of providing a querying service that ensures that a query will not be linkable to the querier. Then, we briefly highlight the characteristics of VANETs, which make the problem different from other types of networks. Finally, we propose a solution for solving the problem by using techniques of pseudoidentity, indistinguishable credentials, and oblivious transfer. We show that, although all infrastructure units collude, it is still impossible to link the real identity of the user to a query. Based on our simulation study, we show that our scheme is effective in terms of processing delay, message overhead, and success rate. © 2011 IEEE.published_or_final_versio

Data Protection for the Internet of Things

The Internet of Things (abbreviated: “IoT”) is acknowledged as one of the most important disruptive technologies with more than 16 billion devices forecasted to interact autonomously by 2020. The idea is simple, devices will help to measure the status of physical objects. The devices, containing sensors and actuators, are so small that they can be integrated or attached to any object in order to measure that object and possibly change its status accordingly. A process or work flow is then able to interact with those devices and to control the objects physically. The result is the collection of massive data in a ubiquitous form. This data can be analysed to gain new insights, a benefit propagated by the “Big Data” and “Smart Data” paradigms. While governments, cities and industries are heavily involved in the Internet of Things, society’s privacy awareness and the concerns over data protection in IoT increase steadily. The scale of the collection, processing and dissemination of possibly private information in the Internet of Things has long begun to raise privacy concerns. The problem is a fundamental one, it is the massive data collection that benefits the investment on IoT, while it contradicts the interest on data minimization coming from privacy advocates. And the challenges go even further, while privacy is an actively researched topic with a mature variety of privacy preserving mechanisms, legal studies and surveillance studies in specific contexts, investigations of how to apply this concepts in the constrained environment of IoT have merely begun. Thus the objective of this thesis is threefold and tackles several topics, looking at them in a differentiated way and later bringing them together for one of the first, (more) complete pictures of privacy in IoT. The first starting point is the throughout study of stakeholders, impact areas and proposals on an architectural reference model for IoT. At the time of this writing, IoT was adversed heavily by several companies, products and even governments, creating a blurred picture of what IoT really is. This thesis surveys stakeholders, scenarios, architecture paradigms and definitions to find a working definition for IoT which adequately describes the intersection between all of the aforementioned topics. In a further step, the definition is applied exemplary on two scenarios to identify the common building blocks of those scenarios and of IoT in general. The building blocks are then verified against a similar approach by the IoT-A and Rerum projects and unified to an IoT domain model. This approach purposefully uses notions and paradigms provided in related scientific work and European projects in order to benefit from existing efforts and to achieve a common understanding. In this thesis, the observation of so called cyber-physical properties of IoT leads to the conclusion that IoT proposals miss a core concept of physical interaction in the “real world”. Accordingly, this thesis takes a detour to jurisdiction and identifies ownership and possession as a main concept of “human-to-object” relationships. The analysis of IoT building blocks ends with an enhanced IoT domain model. The next step breaks down “privacy by design”. Notably hereby is that privacy by design has been well integrated in to the new European General Data Protection Regulation (GDPR). This regulation heavily affects IoT and thus serves as the main source of privacy requirements. Gürses et al.’s privacy paradigm (privacy as confidentiality, privacy as control and privacy as practice) is used for the breakdown, preceded by a survey of relevant privacy proposals, where relevancy was measured upon previously identified IoT impact areas and stakeholders. Independently from IoT, this thesis shows that privacy engineering is a task that still needs to be well understood. A privacy development lifecycle was therefore sketched as a first step in this direction. Existing privacy technologies are part of the survey. Current research is summed up to show that while many schemes exist, few are adequate for actual application in IoT due to their high energy or computational consumption and high implementation costs (most notably caused by the implementation of special arithmetics). In an effort to give a first direction on possible new privacy enhancing technologies for IoT, new technical schemes are presented, formally verified and evaluated. The proposals comprise schemes, among others, on relaxed integrity protection, privacy friendly authentication and authorization as well as geo-location privacy. The schemes are presented to industry partners with positive results. This technologies have thus been published in academia and as intellectual property items. This thesis concludes by bringing privacy and IoT together. The final result is a privacy enhanced IoT domain model accompanied by a set of assumptions regarding stakeholders, economic impacts, economic and technical constraints as well as formally verified and evaluated proof of concept technologies for privacy in IoT. There is justifiable interest in IoT as it helps to tackle many future challenges found in several impact areas. At the same time, IoT impacts the stakeholders that participate in those areas, creating the need for unification of IoT and privacy. This thesis shows that technical and economic constraints do not impede such a process, although the process has merely begun