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  • 51. Kafsi, M.
    et al.
    Papadimitratos, Panagiotis
    Dousse, O.
    Alpcan, T.
    Hubaux, J. -P
    VANET Connectivity Analysis2008In: Proceedings of the IEEE Workshop on Automotive Networking and Applications (Autonet), IEEE , 2008Conference paper (Refereed)
  • 52.
    Kargl, F.
    et al.
    University of Twente.
    Papadimitratos, Panos
    KTH, School of Electrical Engineering (EES), Communication Networks.
    ACM WiSec 2011 poster and demo session2011In: ACM Mobile Computing and Communications Review (ACM MC2R), ISSN 1559-1662, Vol. 15, no 3, p. 34-34Article in journal (Refereed)
  • 53. Kargl, F.
    et al.
    Papadimitratos, Panos
    Buttyan, L.
    Müter, M.
    Wiedersheim, B.
    Schoch, E.
    Thong, T. -V
    Calandriello, G.
    Held, A.
    Kung, A.
    Hubaux, J. -P
    Secure Vehicular Communication Systems: Implementation, Performance, and Research Challenges2008In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 46, p. 110-118Article in journal (Refereed)
  • 54.
    Katselis, Dimitrios
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Communication Networks.
    On secret key generation through multipath for wireless networks2013In: 2013 IEEE International Symposium on Signal Processing and Information Technology (ISSPIT), IEEE Computer Society, 2013, p. 148-153Conference paper (Refereed)
    Abstract [en]

    The complexity of cryptographic key management and the wireless medium salient features motivated a number of works that generate secret keys. Simply put, two nodes can estimate their wireless channel and derive common information to generate a key that other nodes cannot obtain. A gamut of methods, each drawing this information in a different manner, has been proposed. In this landscape, this paper contributes a few findings. First, we propose a method that renders channel impulse response magnitude samples roughly uniform, thus facilitating their quantization and agreement on the derived secret keys. We provide a characterization of the probability of successful agreement for this method, which could be useful for other related methods. Moreover, we consider the cost of the key agreement and we propose a trade-off to increase the probability of success while increasing local processing. With an appropriate configuration, a significant reduction in protocol rounds, and thus communication overhead, for key agreement can be achieved. Through simulations, we validate our approximation of the probability of success and demonstrate the reduced communication overhead.

  • 55.
    Khodaei, Mohammad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Jin, Hongyu
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    SECMACE: Scalable and Robust Identity and Credential Management Infrastructure in Vehicular Communication Systems2018In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 19, no 5, p. 1430-1444Article in journal (Refereed)
    Abstract [en]

    Several years of academic and industrial research efforts have converged to a common understanding on fundamental security building blocks for the upcoming vehicular communication (VC) systems. There is a growing consensus toward deploying a special-purpose identity and credential management infrastructure, i.e., a vehicular public-key infrastructure (VPKI), enabling pseudonymous authentication, with standardization efforts toward that direction. In spite of the progress made by standardization bodies (IEEE 1609.2 and ETSI) and harmonization efforts [Car2Car Communication Consortium (C2C-CC)], significant questions remain unanswered toward deploying a VPKI. Deep understanding of the VPKI, a central building block of secure and privacy-preserving VC systems, is still lacking. This paper contributes to the closing of this gap. We present SECMACE, a VPKI system, which is compatible with the IEEE 1609.2 and ETSI standards specifications. We provide a detailed description of our state-of-the-art VPKI that improves upon existing proposals in terms of security and privacy protection, and efficiency. SECMACE facilitates multi-domain operations in the VC systems and enhances user privacy, notably preventing linking pseudonyms based on timing information and offering increased protection even against honest-but-curious VPKI entities. We propose multiple policies for the vehicle-VPKI interactions and two large-scale mobility trace data sets, based on which we evaluate the full-blown implementation of SECMACE. With very little attention on the VPKI performance thus far, our results reveal that modest computing resources can support a large area of vehicles with very few delays and the most promising policy in terms of privacy protection can be supported with moderate overhead.

  • 56.
    Khodaei, Mohammad
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Jin, Hongyu
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Papadimitratos, Panos
    KTH, School of Electrical Engineering (EES), Communication Networks.
    SECMACE: Scalable and Robust Identity and Credential Management Infrastructure in Vehicular Communication SystemsManuscript (preprint) (Other academic)
    Abstract [en]

    Several years of academic and industrial research efforts have converged to a common understanding on fundamental security building blocks for the upcoming Vehicular Communication (VC) systems. There is a growing consensus towards deploying a special-purpose identity and credential management infrastructure, i.e., a Vehicular Public-Key Infrastructure (VPKI), enabling pseudonymous authentication, with standardization efforts towards that direction. In spite of the progress made by standardization bodies (IEEE 1609.2 and ETSI) and harmonization efforts (Car2Car Communication Consortium (C2C-CC)), significant questions remain unanswered towards deploying a VPKI. The precise understanding of the VPKI, a central building block of secure and privacy-preserving VC systems, is still lacking. This paper contributes to the closing of this gap. We present SECMACE, a VPKI system, which is compatible with the IEEE 1609.2 and ETSI standards specifications. We provide a detailed description of our state-of-the-art VPKI that improves upon existing proposals in terms of security and privacy protection, and efficiency. SECMACE facilitates multi-domain operations in the VC systems and enhances user privacy, notably preventing linking pseudonyms based on timing information and offering increased protection even against honest-but-curious VPKI entities. We propose multiple policies for the vehicle-VPKI interactions based on which and two large mobility traces, we evaluate the full-blown implementation of SECMACE. With very little attention on the VPKI performance thus far, our results reveal that modest computing resources can support a large area of vehicles with very low delays and the most promising policy in terms of privacy protection can be supported with moderate overhead.

  • 57.
    Khodaei, Mohammad
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Jin, Hongyu
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Papadimitratos, Panos
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Towards deploying a scalable & robust vehicular identity and credential management infrastructure2014In: Vehicular Networking Conference (VNC), 2014 IEEE, IEEE conference proceedings, 2014, Vol. -, no -, p. 33-40Conference paper (Refereed)
    Abstract [en]

    - Several years of academic and industrial research efforts have converged to a common understanding on fundamental security building blocks for the upcoming Vehicular Communication (VC) systems. There is a growing consensus towards deploying a Vehicular Public-Key Infrastructure (VPKI) enables pseudonymous authentication, with standardization efforts in that direction. However, there are still significant technical issues that remain unresolved. Existing proposals for instantiating the VPKI either need additional detailed specifications or enhanced security and privacy features. Equally important, there is limited experimental work that establishes the VPKI efficiency and scalability. In this paper, we are concerned with exactly these issues. We leverage the common VPKI approach and contribute an enhanced system with precisely defined, novel features that improve its resilience and the user privacy protection. In particular, we depart from the common assumption that the VPKI entities are fully trusted and we improve user privacy in the face of an honest-but-curious security infrastructure. Moreover, we fully implement our VPKI, in a standard-compliant manner, and we perform an extensive evaluation. Along with stronger protection and richer functionality, our system achieves very significant performance improvement over prior systems - contributing the most advanced VPKI towards deployment.

  • 58.
    Khodaei, Mohammad
    et al.
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Messing, Andreas
    KTH, School of Computer Science and Communication (CSC).
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    RHyTHM: A Randomized Hybrid Scheme To Hide in the Mobile Crowd2017In: IEEE Vehicular Networking Conference (VNC) 2017, IEEE, 2017, p. 155-158Conference paper (Refereed)
    Abstract [en]

    Any on-demand pseudonym acquisition strategy is problematic should the connectivity to the credential management infrastructure be intermittent. If a vehicle runs out of pseudonyms with no connectivity to refill its pseudonym pool, one solution is the on-the-fly generation of pseudonyms, e.g., leveraging anonymous authentication. However, such a vehicle would stand out in the crowd: one can simply distinguish pseudonyms, thus signed messages, based on the pseudonym issuer signature, link them and track the vehicle. To address this challenge, we propose a randomized hybrid scheme, RHyTHM, to enable vehicles to remain operational when disconnected without compromising privacy: vehicles with valid pseudonyms help others to enhance their privacy by randomly joining them in using on-the-fly self-certified pseudonyms along with aligned lifetimes. This way, the privacy of disconnected users is enhanced with a reasonable computational overhead. 

  • 59.
    Khodaei, Mohammad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Noroozi, Hamid
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Privacy Preservation through Uniformity2018In: Proceedings of the ACM Conference on Security and Privacy in Wireless & Mobile Networks (WiSec), Stockholm, Sweden, June 2018., ACM Digital Library, 2018Conference paper (Refereed)
    Abstract [en]

    Inter-vehicle communications disclose rich information about vehicle whereabouts. Pseudonymous authentication secures communication while enhancing user privacy thanks to a set of anonymized certificates, termed pseudonyms. Vehicles switch the pseudonyms (and the corresponding private key) frequently; we term this pseudonym transition process. However, exactly because vehicles can in principle change their pseudonyms asynchronously, an adversary that eavesdrops (pseudonymously) signed messages, could link pseudonyms based on the times of pseudonym transition processes. In this poster, we show how one can link pseudonyms of a given vehicle by simply looking at the timing information of pseudonym transition processes. We also propose "mix-zone everywhere": time-aligned pseudonyms are issued for all vehicles to facilitate synchronous pseudonym update; as a result, all vehicles update their pseudonyms simultaneously, thus achieving higher user privacy protection.

  • 60.
    Khodaei, Mohammad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Noroozi, Hamid
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Scaling Pseudonymous Authentication for Large Mobile Systems2019In: WiSec 2019 - Proceedings of the 2019 Conference on Security and Privacy in Wireless and Mobile Networks, Miami, FL, USA, 2019, p. 174-185Conference paper (Refereed)
    Abstract [en]

    The central building block of secure and privacy-preserving Vehicular Communication (VC) systems is a Vehicular Public-Key Infrastructure (VPKI), which provides vehicles with multiple anonymized credentials, termed pseudonyms. These pseudonyms are used to ensure message authenticity and integrity while preserving vehicle (thus passenger) privacy. In the light of emerging large-scale multi-domain VC environments, the efficiency of the VPKI and, more broadly, its scalability are paramount. By the same token, preventing misuse of the credentials, in particular, Sybil-based misbehavior, and managing “honest-but-curious” insiders are other facets of a challenging problem. In this paper, we leverage the state-of-the-art VPKI system and enhance its functionality towards a highly-available, dynamically-scalable, and resilient design; this ensures that the system remains operational in the presence of benign failures or resource depletion attacks, and that it dynamically scales out, or possibly scales in, according to request arrival rates. Our full-blown implementation on the Google Cloud Platform shows that deploying large-scale and efficient VPKI can be cost-effective.

  • 61.
    Khodaei, Mohammad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    A Cooperative Location Privacy Protection Scheme for Vehicular Ad-hoc Networks2019Report (Other academic)
  • 62.
    Khodaei, Mohammad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Efficient, Scalable, and Resilient Vehicle-Centric Certificate Revocation List Distribution in VANETs2018In: Proceedings of the ACM Conference on Security and Privacy in Wireless & Mobile Networks (WiSec), Stockholm, Sweden, June 2018., 2018Conference paper (Refereed)
    Abstract [en]

    In spite of progress in securing Vehicular Communication (VC) systems, there is no consensus on how to distribute Certificate Revocation Lists (CRLs). The main challenges lie exactly in (i) crafting an efficient and timely distribution of CRLs for numerous anonymous credentials, pseudonyms, (ii) maintaining strong privacy for vehicles prior to revocation events, even with honest-but-curious system entities, (iii) and catering to computation and communication constraints of on-board units with intermittent connectivity to the infrastructure. Relying on peers to distribute the CRLs is a double-edged sword: abusive peers could ‘‘pollute’’ the process, thus degrading the timely CRLs distribution. In this paper, we propose a vehicle-centric solution that addresses all these challenges and thus closes a gap in the literature. Our scheme radically reduces CRL distribution overhead: each vehicle receives CRLs corresponding only to its region of operation and its actual trip duration. Moreover, a ‘‘fingerprint’’ of CRL ‘pieces’ is attached to a subset of (verifiable) pseudonyms for fast CRL ‘piece’ validation (while mitigating resource depletion attacks abusing the CRL distribution). Our experimental evaluation shows that our scheme is efficient, scalable, dependable, and practical: with no more than 25 KB/s of traffic load, the latest CRL can be delivered to 95% of the vehicles in a region (50×50 KM) within 15s, i.e., more than 40 times faster than the state-of-the-art. Overall, our scheme is a comprehensive solution that complements standards and can catalyze the deployment of secure and privacy-protecting VC systems.

  • 63.
    Khodaei, Mohammad
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Papadimitratos, Panos
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Evaluating On-demand Pseudonym Acquisition Policies in Vehicular Communication Systems2016Conference paper (Refereed)
    Abstract [en]

    Standardization and harmonization efforts have reached a consensus towards using a special-purpose Vehicular Public-Key Infrastructure (VPKI) in upcoming Vehicular Communication (VC) systems. However, there are still several technical challenges with no conclusive answers; one such an important yet open challenge is the acquisition of shortterm credentials, pseudonym: how should each vehicle interact with the VPKI, e.g., how frequently and for how long? Should each vehicle itself determine the pseudonym lifetime? Answering these questions is far from trivial. Each choice can affect both the user privacy and the system performance and possibly, as a result, its security. In this paper, we make a novel systematic effort to address this multifaceted question. We craft three generally applicable policies and experimentally evaluate the VPKI system performance, leveraging two large-scale mobility datasets. We consider the most promising, in terms of efficiency, pseudonym acquisition policies; we find that within this class of policies, the most promising policy in terms of privacy protection can be supported with moderate overhead. Moreover, in all cases, this work is the first to provide tangible evidence that the state-of-the-art VPKI can serve sizable areas or domain with modest computing resources.

  • 64.
    Khodaei, Mohammad
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Papadimitratos, Panos
    KTH, School of Electrical Engineering (EES), Communication Networks.
    The Key to Intelligent Transportation: Identity and Credential Management in Vehicular Communication Systems2015In: IEEE Vehicular Technology Magazine, ISSN 1556-6072, E-ISSN 1556-6080, Vol. 10, no 4, p. 63-69, article id 1556-6072Article in journal (Refereed)
    Abstract [en]

    Vehicular Communication (VC) systems will greatly enhance intelligent transportation systems. But their security and the protection of their users’ privacy are a prerequisite for deployment. Efforts in industry and academia brought forth a multitude of diverse proposals. These have now converged to a common view, notably on the design of a security infrastructure, a Vehicular Public Key Infrastructure (VPKI) that shall enable secure conditionally anonymous VC. Standardization efforts and industry readiness to adopt this approach hint to its maturity. However, there are several open questions remaining, and it is paramount to have conclusive answers before deployment. In this article, we distill and critically survey the state of the art for identity and credential management in VC systems, and we sketch a roadmap for addressing a set of critical remaining security and privacy challenges.

  • 65. Leinmüller, T.
    et al.
    Buttyan, L.
    Hubaux, J. P.
    Kargl, F.
    Kroh, R.
    Papadimitratos, Panos
    Raya, M.
    Schoch, E.
    SEVECOM - Secure Vehicle Communication2006In: Proceedings of IST Mobile Summit, 2006Conference paper (Refereed)
  • 66. Luo, J.
    et al.
    Papadimitratos, Panagiotis
    Hubaux, J-P
    GossiCrypt: Wireless Sensor Network Data Confidentiality Against Parasitic Adversaries2008In: Proceedings of the Fifth IEEE-CS Conference on Sensor, Mesh and Ad Hoc Communications and Networks (SECON), 2008, p. 441-450Conference paper (Refereed)
  • 67.
    Manolopoulos, Vasileios
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Papadimitratos, Panos
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Tao, Sha
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Rusu, Ana
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Securing smartphone based ITS2011In: ITST 2011: Proceedings of the 11th International Conference on ITS Telecommunications, 2011, 2011, p. 201-206Conference paper (Refereed)
    Abstract [en]

    GPS-equipped smartphones present several advantages for data acquisition in Intelligent Transportation Systems (ITS), compared to solutions that require a new communication infrastructure. However, there are still significant challenges to meet before deployment. Traffic information and location samples must be collected in a secure manner, to not jeopardize the system operation. Equally important, users must be assured about their privacy, notably the protection of information on their whereabouts. To address this two-fold problem, we propose extending the Generic Bootstrapping Architecture (GBA) with anonymous authentication. Identity and location information are protected and separated, and location samples cannot be linked to each other and to any specific user. Thus, our scheme protects users even in the case of a compromised ITS server. Initial evaluation results indicate the feasibility of our approach with off-the-self mobile platforms.

  • 68.
    Manolopoulos, Vasileios
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Tao, Sha
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Rusu, Ana
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Smartphone-based Traffic Information System for Sustainable Cities2012In: Mobile Computing and Communications Review, ISSN 1559-1662, Vol. 16, no 4, p. 30-31Article in journal (Refereed)
    Abstract [en]

    Traffic Information Systems (TISs) can play a significant role towards creating sustainable cities through improved traffic conditions. The collection of reliable and rich information with low cost is paramount. The use of smartphones carried by individuals for future implementations of TISs present several advantages compared to traditional solutions. This demo integrates our results from previous work addressing challenges on traffic estimation for urban road networks and on security and privacy protection for such TISs.

  • 69.
    Manolopoulos, Vasileios
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Tao, Sha
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Rusu, Ana
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Papadimitratos, Panos
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Smartphone-based Traffic Information System for Sustainable Cities2012Conference paper (Refereed)
  • 70. Mezzour, G.
    et al.
    Perrig, A.
    Gligor, V.
    Papadimitratos, Panagiotis
    Privacy-Preserving Relationship Path Discovery in Social Networks2009In: Proceedings of the 8th International Conference on Cryptology and Network Security, Springer , 2009, p. 189-208Conference paper (Refereed)
  • 71. Mirmohseni, M.
    et al.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Active adversaries from an information-theoretic perspective: Data modification attacks2014In: IEEE International Symposium on Information Theory - Proceedings, 2014, p. 791-795Conference paper (Refereed)
    Abstract [en]

    We investigate the problem of reliable communication in the presence of active adversaries that can tamper with the transmitted data. We consider a legitimate transmitter-receiver pair connected over multiple communication paths (routes). We propose two new models of adversary, a 'memoryless' and a 'foreseer' adversary. For both models, the adversaries are placing themselves arbitrarily on the routes, keeping their placement fixed throughout the transmission block. This placement may or may not be known to the transmitter. The adversaries can choose their best modification strategy to increase the error at the legitimate receiver, subject to a maximum distortion constraint. We investigate the communication rates that can be achieved in the presence of the two types of adversaries and the channel (benign) stochastic behavior. For memoryless adversaries, the capacity is derived. Our method is to use the typical set of the anticipated received signal for all possible adversarial strategies (including their best one) in a compound channel that also captures adversarial placement. For the foreseer adversaries, which have enhanced observation capabilities compared to the memoryless ones, we propose a new coding scheme to guarantee resilience, i.e., recovery of the codeword independently of the adversarial (best) choice. We derive an achievable rate and we propose an upper bound on the capacity. We evaluate our general results for specific cases (e.g., binary symbol replacement or erasing attacks), to gain insights.

  • 72. Mirmohseni, M.
    et al.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Colluding eavesdroppers in large cooperative wireless networks2014In: IWCIT 2014 - Iran Workshop on Communication and Information Theory, IEEE , 2014Conference paper (Refereed)
    Abstract [en]

    Securing communication against non-colluding passive eavesdroppers has been extensively studied. Colluding eavesdroppers were considered for interference-limited large networks. However, collusion was not investigated for large cooperative networks. This paper closes this gap: we study the improvement the eavesdroppers achieve due to collusion in terms of the information leakage rate in a large cooperative network. We consider a dense network with nl legitimate nodes, ne eavesdroppers, and path loss exponent α ≥ 2. We show that if ne (2+2/α) (log ne)γ = o(n l) holds, for some positive γ, then zero-cost secure communication is possible; i.e., ne colluding eavesdroppers can be tolerated. This means that our scheme achieves unbounded secure aggregate rate, given a fixed total power constraint for the entire network.

  • 73.
    Mirmohseni, Mahtab
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Constrained colluding eavesdroppers: an information-theoretic model2014In: International Zurich Seminar on Communications, ETH-Zürich , 2014, p. 63-66Conference paper (Refereed)
    Abstract [en]

    We study the secrecy capacity in the vicinity of colluding eavesdroppers. Contrary to the perfect collusion assumption in previous works, our new information-theoretic model considers constraints in collusion. We derive the achievable secure rates (lower bounds on the perfect secrecy capacity), both for the discrete memoryless and Gaussian channels. We also compare the proposed rates to the non-colluding and perfect colluding cases.

  • 74.
    Mirmohseni, Mahtab
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Scaling laws for secrecy capacity in cooperative wireless networks2014In: INFOCOM, 2014 Proceedings IEEE, 2014, p. 1527-1535Conference paper (Refereed)
    Abstract [en]

    We investigate large wireless networks subject to security constraints. In contrast to point-to-point, interference-limited communications considered in prior works, we propose active cooperative relaying based schemes. We consider a network with  legitimate nodes,  eavesdroppers, and path loss exponent . As long as , for some positive , we show one can obtain unbounded secure aggregate rate. This means zero-cost secure communication, given fixed total power constraint for the entire network. We achieve this result through (i) the source using Wyner randomized encoder and a serial (multi-stage) block Markov scheme, to cooperate with the relays and (ii) the relays acting as a virtual multi-antenna to apply beamforming against the eavesdroppers. Our simpler parallel (two-stage) relaying scheme can achieve the same unbounded secure aggregate rate when  holds, for some positive .

  • 75. Mirmohseni, Mahtab
    et al.
    Papadimitratos, Panagiotis Panos
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Secrecy Capacity Scaling in Large Cooperative Wireless Networks2017In: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 63, no 3, p. 1923-1939Article in journal (Refereed)
    Abstract [en]

    We investigate large wireless networks subject to security constraints. In contrast to point-to-point, interference-limited communications considered in prior works, we propose active cooperative relaying-based schemes. We consider a network with n(l) legitimate nodes, n(e) eavesdroppers, and path loss exponent alpha >= 2. As long as n(e)(2)(log(n(e))(gamma) = o(n(l)), for some positive gamma, we show that one can obtain unbounded secure aggregate rate. This means zero-cost secure communication, given fixed total power constraint for the entire network. We achieve this result through: 1) the source using Wyner randomized encoder and a serial ( multi-stage) block Markov scheme, to cooperate with the relays and 2) the relays acting as a virtual multi-antenna to apply beamforming against the eavesdroppers. Our simpler parallel ( two-stage) relaying scheme can achieve the same unbounded secure aggregate rate when n(e)(alpha/2+1) (log(n(e))(gamma+delta(alpha/2+1)) = o(n(l)) holds, for some positive gamma, delta. Finally, we study the improvement (to the detriment of legitimate nodes) that the eavesdroppers achieve in terms of the information leakage rate in a large cooperative network in the case of collusion. We show that again the zero-cost secure communication is possible, if n(e)((2+2/alpha)) (log n(e))(gamma) = o(n(l)) holds, for some positive gamma; that is, in the case of collusion slightly fewer eavesdroppers can be tolerated compared with the non-colluding case.

  • 76. Moore, T.
    et al.
    Raya, M.
    Clulow, J.
    Papadimitratos, Panagiotis
    Anderson, R.
    Hubaux, J-P
    Fast Exclusion of Errant Devices from Vehicular Networks2008In: Proceedings of the Fifth IEEE-CS Conference on Sensor, Mesh and Ad Hoc Communications and Networks (SECON), IEEE , 2008, p. 135-143Conference paper (Refereed)
  • 77. Neuberg, C.
    et al.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Fragouli, C.
    Urbanke, R.
    A Mobile World of Security - The Model2011In: IEEE Information Theory Society Conference on Information Sciences and Systems (CISS), IEEE , 2011, p. 1-6Conference paper (Refereed)
    Abstract [en]

    We propose a novel approach to establish cryptographic keys among mobile users and a networking infrastructure. Our approach comes at a low cost and can either be used as an alternative to existing solutions or can be employed in a complementary way. Our basic observation is that users are often very mobile. As they interact with the infrastructure, each of them leaves a unique trace behind, known both to the users and the infrastructure. We can leverage this shared information to create shared secret keys, with little or no change of existing mobile communication systems. We show that we can achieve (almost passively) a rate of roughly 0.1 bits per second.

  • 78.
    Noroozi, Hamid
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Khodaei, Mohammad
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    VPKIaaS: A highly-available and dynamically-scalable vehicular public-key infrastructure2018In: WiSec 2018 - Proceedings of the 11th ACM Conference on Security and Privacy in Wireless and Mobile Networks, Association for Computing Machinery, Inc , 2018, p. 302-304Conference paper (Refereed)
    Abstract [en]

    The central building block of secure and privacy-preserving Vehicular Communication (VC) systems is a Vehicular Public-Key Infrastructure (VPKI), which provides vehicles with multiple anonymized credentials, termed pseudonyms. These pseudonyms are used to ensure message authenticity and integrity while preserving vehicle (and thus passenger) privacy. In the light of emerging large-scale multi-domain VC environments, the efficiency of the VPKI and, more broadly, its scalability are paramount. In this extended abstract, we leverage the state-of-the-art VPKI system and enhance its functionality towards a highly-available and dynamically-scalable design; this ensures that the system remains operational in the presence of benign failures or any resource depletion attack, and that it dynamically scales out, or possibly scales in, according to the requests' arrival rate. Our full-blown implementation on the Google Cloud Platform shows that deploying a VPKI for a large-scale scenario can be cost-effective, while efficiently issuing pseudonyms for the requesters.

  • 79.
    Noroozi, Hamid
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Khodaei, Mohammad
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering.
    Papadimitratos, Panos
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    VPKIaaS: Towards Scaling Pseudonymous Authentication for Large Mobile Systems2019Report (Other academic)
  • 80. Panchard, J.
    et al.
    Rao, S.
    Sheshshayee, M.
    Papadimitratos, Panagiotis
    Kumar, S.
    Hubaux, J. P.
    Wireless Sensor Networking for Rain-fed Farming Decision Support2008In: Proceedings of the ACM SIGCOMM Worskhop on Networked Systems for Developing Regions, 2008, p. 31-36Conference paper (Refereed)
  • 81.
    Papadimitratos, P.
    et al.
    School of Electrical and Computer Engineering, Cornell University.
    Haas, Z. J.
    chool of Electrical and Computer Engineering, Cornell University.
    Securing Mobile Ad Hoc Networks2005In: Mobile Computing Handbook / [ed] Mohammad Ilyas, Imad Mahgoub, Boca Raton, FL: Auerbach Publications , 2005Chapter in book (Other academic)
  • 82. Papadimitratos, P.
    et al.
    Hubaux, J. -P
    Secure Vehicular Communication Systems2011In: Encyclopedia of Cryptography and Security / [ed] H.C.A. van Tilborg and S. Jajodia, Berlin: Springer , 2011, 2, p. 1140-1143Chapter in book (Other academic)
  • 83. Papadimitratos, Panagioitis
    et al.
    Mezzour, G.
    Hubaux, J. -P
    Certificate Revocation List Distribution in Vehicular Communication Systems2008In: Proceedings of the Fifth ACM International Workshop on Vehicular Inter-NETworking (VANET'08), ASSOC COMPUTING MACHINERY , 2008, p. 86-87Conference paper (Refereed)
    Abstract [en]

    The need to evict compromised, faulty, or illegitimate nodes is well understood in prominent projects designing security architectures for Vehicular Communication (VC) systems. The basic approach envisioned to achieve this is via distribution of Certificate Revocation Lists (CRLs). Nonetheless, the problem of how to distribute CRLs effectively and efficiently has not been investigated. In this paper, we addresses exactly this problem. We propose a flexible, simple, and scalable design that leverages on road-side VC infrastructure. Our scheme can distribute large CRLs across wide VC regions within minutes, by utilizing a bandwidth of only a few Kbps at each road-side infrastructure unit.

  • 84.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Digital Signatures2011In: Modern Cryptography: Theory and Applications / [ed] M. Burmester, S. Gritzalis, S. Katsikas, V. Chrissikopoulos, Athens: Papasotiriou Books , 2011Chapter in book (Other academic)
  • 85. Papadimitratos, Panagiotis
    “On the road”: Reflections on the Security of Vehicular Communication Systems2008In: Proceedings of the IEEE International Conference on Vehicular Electronics and Safety (ICVES), IEEE , 2008, p. 359-363Conference paper (Other academic)
  • 86. Papadimitratos, Panagiotis
    Secure Ad hoc Networking2006In: Proceedings of the IEEE Consumer Communications and Networking Conference (CCNC), 2006, Vol. 1, p. 10-14Conference paper (Other academic)
  • 87.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Security on Wheels: Security and Privacy for Vehicular Communication Systems2016In: CCS'16: PROCEEDINGS OF THE 2016 ACM SIGSAC CONFERENCE ON COMPUTER AND COMMUNICATIONS SECURITY, Association for Computing Machinery (ACM), 2016, p. 1855-1856Conference paper (Refereed)
    Abstract [en]

    There is already a significant body of work on security and privacy for vehicular communication systems and the conditions for deploying the technology are maturing. This tutorial provides a crystalized and easily accessible view of the state of the art.

  • 88. Papadimitratos, Panagiotis
    et al.
    Ardelean, P.
    Secure and Privacy-Enhancing Vehicular Communication: Demonstration of Implementation and Operation2008In: Proceedings of the IEEE Vehicular Technology Conference (VTC-Fall), IEEE , 2008, p. 1-2Conference paper (Refereed)
  • 89. Papadimitratos, Panagiotis
    et al.
    Buttyan, L.
    Holczer, T.
    Schoch, E.
    Freudiger, J.
    Raya, M.
    Ma, Z.
    Kargl, F.
    Kung, A.
    Hubaux, J. -P
    Secure Vehicular Communication Systems: Design and Architecture2008In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 46, p. 100-109Article in journal (Refereed)
  • 90. Papadimitratos, Panagiotis
    et al.
    Buttyan, L.
    Hubaux, J.-P.
    Kargl, F.
    Kung, A.
    Raya, M.
    Architecture for Secure and Private Vehicular Communications2007In: IEEE International Conference on ITS Telecommunications (IEEE ITST), IEEE , 2007, p. 1-6Conference paper (Refereed)
  • 91. Papadimitratos, Panagiotis
    et al.
    Calandriello, G.
    Lioy, A.
    Hubaux, J.-P.
    Impact of Vehicular Communication Security on Transportation Safety2008In: Proceedings of the 28th IEEE Conference on Computer Communications (INFOCOM) Workshop on Mobile Networking for Vehicular Environments (MOVE), 2008, p. 1-6Conference paper (Refereed)
  • 92.
    Papadimitratos, Panagiotis
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Deng, J.
    Stealthy pre-attacks against random key pre-distribution security2012In: Communications (ICC), 2012 IEEE International Conference on, IEEE , 2012, p. 955-959Conference paper (Refereed)
    Abstract [en]

    Random key pre-distribution (RKPD) has been investigated for large wireless sensor networks, in order to achieve efficient security and robustness against limited node compromise. While it is possible that an adversary obtains a subset of the symmetric keys in use, it has been unclear how to use those to compromise specific secure links. We investigate how the adversary could do this practically. We term this the Stealthy Pre-Attack (SPA), because the adversarial nodes leverage benign behavior to guide their attack. The contribution of this paper is the identification of this adversarial behavior, the evaluation of its benefits for the attacker, which can then much more effectively compromise security, and the proposal of counter-measures to mitigate it.

  • 93. Papadimitratos, Panagiotis
    et al.
    Fortelle, A. La
    Evenssen, K.
    Brignolo, R.
    Cosenza, S.
    Vehicular Communication Systems: Enabling Technologies, Applications, and Future Outlook on Intelligent Transportation2009In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 47, no 11, p. 84-95Article in journal (Refereed)
  • 94. Papadimitratos, Panagiotis
    et al.
    Gligor, V.
    Hubaux, J. -P
    Securing Vehicular Communications - Assumptions, Requirements, and Principles2006In: Proceedings of the Fourth Workshop on Embedded Security in Cars (ESCAR), 2006, p. 5-14Conference paper (Refereed)
  • 95. Papadimitratos, Panagiotis
    et al.
    Haas, Z. J.
    Secure Data Communication in Mobile Ad Hoc Networks2006In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 24, no 2, p. 343-356Article in journal (Refereed)
    Abstract [en]

    We address the problem of secure and fault-tolerant communication in the presence of adversaries across a multihop wireless network with frequently changing topology. To effectively cope with arbitrary malicious disruption of data transmissions, we propose and evaluate the secure message transmission (SMT) protocol and its alternative, the secure single-path (SSP) protocol. Among the salient features of SMT and SSP is their ability to operate solely in an end-to-end manner and without restrictive assumptions on the network trust and security associations. As a result, the protocols are applicable to a wide range of network architectures. We demonstrate that highly reliable communication can be sustained with small delay and small delay variability, even when a substantial portion of the network nodes systematically or intermittently disrupt communication. SMT and SSP robustly detect transmission failures and continuously configure their operation to avoid and tolerate data loss, and to ensure the availability of communication. This is achieved at the expense of moderate transmission and routing overhead, which can be traded off for delay. Overall, the ability of the protocols to mitigate both malicious and benign faults allows fast and reliable data transport even in highly adverse network environments.

  • 96. Papadimitratos, Panagiotis
    et al.
    Haas, Z. J.
    Secure Data Transmission in Mobile Ad Hoc Networks2003In: Proceedings of the ACM MobiCom Workshop on Wireless Security (WiSe), 2003, p. 41-50Conference paper (Refereed)
    Abstract [en]

    The vision of nomadic computing with its ubiquitous access has stimulated much interest in the Mobile Ad Hoc Networking (MANET) technology. However, its proliferation strongly depends on the availability of security provisions, among other factors. In the open, collaborative MANET environment practically any node can maliciously or selfishly disrupt and deny communication of other nodes. In this paper, we present and evaluate the Secure Message Transmission (SMT) protocol, which safeguards the data transmission against arbitrary malicious behavior of other nodes. SMT is a lightweight, yet very effective, protocol that can operate solely in an end-to-end manner. It exploits the redundancy of multi-path routing and adapts its operation to remain efficient and effective even in highly adverse environments. SMT is capable of delivering up to 250% more data messages than a protocol that does not secure the data transmission. Moreover, SMT outperforms an alternative single-path protocol, a secure data forwarding protocol we term Secure Single Path (SSP) protocol. SMT imposes up to 68% less routing overhead than SSP, delivers up to 22% more data packets and achieves end-to-end delays that are up to 94% lower than those of SSP. Thus, SMT is better suited to support QoS for real-time communications in the ad hoc networking environment. The security of data transmission is achieved without restrictive assumptions on the network nodes' trust and network membership, without the use of intrusion detection schemes, and at the expense of moderate multi-path transmission overhead only.

  • 97. Papadimitratos, Panagiotis
    et al.
    Haas, Z. J.
    Secure Link State Routing for Mobile Ad Hoc Networks2003In: Proceedings of the IEEE Symposium on Applications and the Internet Workshop on Security and Assurance in Ad hoc Networks, 2003, p. 379-383Conference paper (Refereed)
  • 98. Papadimitratos, Panagiotis
    et al.
    Haas, Z. J.
    Secure On-Demand Distance Vector Routing in Ad hoc Networks2005In: Proceedings of the IEEE Sarnoff Symposium on Advances in Wired and Wireless Communication, IEEE , 2005, p. 168-171Conference paper (Refereed)
  • 99. Papadimitratos, Panagiotis
    et al.
    Haas, Z. J.
    Secure Route Discovery for QoS-Aware Routing in Ad Hoc Networks2005In: Proceedings of the IEEE Sarnoff Symposium on Advances in Wired and Wireless Communications, IEEE , 2005, p. 176-179Conference paper (Refereed)
  • 100. Papadimitratos, Panagiotis
    et al.
    Haas, Z. J.
    Secure Routing for Mobile Ad Hoc Networks2003In: ACM SIGMOBILE Mobile Computing and Communications Review (MC2R) - Special Issue: Report on a Working Session on Security in Wireless Ad hoc Networks, Vol. 7, no 1, p. 79-80Article in journal (Refereed)
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