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Akgun M.,Tubitak UEKAE | Caglayan M.U.,Istanbul University
Proceedings - International Conference on Network Protocols, ICNP | Year: 2014

Many RFID authentication protocols have been proposed to provide desired security and privacy level for RFID systems. Almost all of these protocols are based on symmetric cryptography because of the limited resources of RFID tags. Recently Cheng et. Al have proposed an RFID security protocol based on chaotic maps. In this paper, we analyse the security of this protocol and discover its vulnerabilities. We firstly present a de-synchronization attack in which a passive adversary makes the shared secrets out-of-synchronization by eavesdropping just one protocol session. We secondly present a secret disclosure attack in which a passive adversary extracts secrets of a tag by eavesdropping just one protocol session. An adversary having the secrets of the tag can launch some other attacks. Finally, we propose modifications to Cheng et. Al's protocol to eliminate its vulnerabilities. © 2014 IEEE. Source

Akgun M.,Tubitak UEKAE | Akgun M.,Istanbul University | Calayan M.U.,Istanbul University
Ad Hoc Networks | Year: 2015

Abstract Internet of Things (IoT) emerges as a global network in which any things (including humans and the real world things) having unique identifier can communicate each other. The RFID system has very important role in the IoT system for solving the identification issues of things cost-effectively. However, RFID systems have serious security and privacy issues. In the literature, there are many proposals that aim to solve to security and privacy issues of RFID systems. The common drawback of these solution is scalability because they generally require a linear search on the back-end database in order to identify a tag. Some proposals use tree structures to store the keys. They reduce the search complexity from O(n) to O(log n). However, these protocols are susceptible to compromising attack in which an adversary compromising one tag can reveal the secrets of other tags. That means tree-based protocols can provide only a weak level of privacy. In this paper, we propose a scalable authentication protocol for RFID systems. Our solution utilizes Physically Unclonable Functions (PUFs) in order to achieve higher level of privacy with constant identification time. It provides destructive privacy according to the Vaudenay's privacy and security model. It defends against compromising attack by using PUFs as a secure storage to keep secrets of the tag. To the best of our knowledge, it is the first protocol providing such a privacy level with constant identification time. © 2015 Elsevier B.V. Source

Sezgin M.,Tubitak UEKAE
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

In this paper hand-held dual sensor detector development requirements are considered dedicated to buried object detection. Design characteristics of such a system are categorized and listed. Hardware and software structures, ergonomics, user interface, environmental and EMC/EMI tests to be applied and performance test issues are studied. Main properties of the developed system (SEZER) are presented, which contains Metal Detector (MD) and Ground Penetrating Radar (GPR). The realized system has ergonomic structure and can detect both metallic and non-metallic buried objects. Moreover classification of target is possible if it was defined to the signal processing software in learning phase. © 2010 Copyright SPIE - The International Society for Optical Engineering. Source

Eksim A.,Tubitak UEKAE | Celebi M.E.,Technical University of Istanbul
IETE Technical Review (Institution of Electronics and Telecommunication Engineers, India) | Year: 2010

The statistical cooperative diversity, based on space-time block codes (statistical STBC cooperative -diversity) is proposed for binary sensors by several authors. Since Alamouti's code is the only orthogonal code which achieves full diversity and full rate for two sensors, it is used in their works, and their achievable diversity order is 2. Instead of using Alamouti's code, we use extended cooperative space-time block coding (ECBSTBC) which achieves full diversity which is shown analytically and full rate for an arbitrary number of sensors if a limited feedback is available at the active sensors. Another method to increase diversity in cooperative communications is sensor (relay) selection. However, the sensor selection method may lead to the selection of the same (near) sensor for transmission over a long period causing the energy hole problem in sensor networks. The ECBSTBC which utilizes every sensor in sight thus distributes the energy consumption among active sensors and alleviates the energy hole problem. In addition, it can be shown with detailed simulations that the ECBSTBC outperforms both the statistical STBC cooperative diversity and the sensor selection schemes. Copyright © 2009 by the IETE. Source

Akgun M.,Tubitak UEKAE | Caglayan M.U.,Istanbul University
IWCMC 2015 - 11th International Wireless Communications and Mobile Computing Conference | Year: 2015

Radio Frequency Identification (RFID) protocols should have a secret updating phase in order to protect the privacy of RFID tags against tag tracing attacks. In the literature, there are many lightweight RFID authentication protocols that try to provide key updating with lightweight cryptographic primitives. In this paper, we analyze the security of two recently proposed lightweight RFID authentication protocol against desynchronization attacks. We show that secret values shared between the back-end server and any given tag can be easily desynchronized. This weakness stems from the insufficient design of these protocols. © 2015 IEEE. Source

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