Solution of a Conjecture: On 2-PCD RFID Distance Bounding Protocols

The file attached to this record is the author's final peer reviewed version.It is a popular challenge to design distance bounding protocols that are both secure and efficient. Motivated by this, many distance bounding protocols against relay attacks have been advanced in recent times. Another interesting question is whether these protocols provides the best security. In 2010, Kara et al. analysis the optimal security limits of low-cost distance bounding protocols having bit-wise fast phases and no final signature. As for the classification, they have introduced the notion of k-previous challenge dependent (k-PCD) protocols where each response bit depends on the current and the k previous challenges. They have given the theoretical security bounds for two specific classes k = 0 and 1, but have left the security bounds for k >= 2 as an open problem. In this paper, we aim to answer the open question concerning the security limits of 2-PCD protocols. We describe two generic attacks for mafia and distance frauds that can be applied on any 2-PCD protocols. Then, we provide the optimal trade-off curve between the security levels of mafia and distance frauds that determines the security limits of 2-PCD protocols. Finally our results also prove the conjecture that 2-PCD protocols enhance the security compared to 0-PCD and 1-PCD cases

Computational and symbolic analysis of distance-bounding protocols

Contactless technologies are gaining more popularity everyday. Credit cards enabled with contactless payment, smart cards for transport ticketing, NFC-enabled mobile phones, and e-passports are just a few examples of contactless devices we are familiar with nowadays. Most secure systems meant for these devices presume physical proximity between the device and the reader terminal, due to their short communication range. In theory, a credit card should not be charged of an on-site purchase if the card is not up to a few centimeters away from the payment terminal. In practice, this is not always true. Indeed, some contactless payment protocols, such as Visa's payWave, have been shown vulnerable to relay attacks. In a relay attack, a man-in-the-middle uses one or more relay devices in order to make two distant devices believe they are close. Relay attacks have been implemented also to bypass keyless entry and start systems in various modern cars. Relay attacks can be defended against with distance-bounding protocols, which are security protocols that measure the round-trip times of a series of challenge/response rounds in order to guarantee physical proximity. A large number of these protocols have been proposed and more sophisticated attacks against them have been discovered. Thus, frameworks for systematic security analysis of these protocols have become of high interest. As traditional security models, distance-bounding security models sit within the two classical approaches: the computational and the symbolic models. In this thesis we propose frameworks for security analysis of distance-bounding protocols, within the two aforementioned models. First, we develop an automata-based computational framework that allows us to generically analyze a large class of distance-bounding protocols. Not only does the proposed framework allow us to straightforwardly deliver computational (in)security proofs but it also permits us to study problems such as optimal trade-offs between security and space complexity. Indeed, we solve this problem for a prominent class of protocols, and propose a protocol solution that is optimally secure amongst space-constrained protocols within the considered class. Second, by building up on an existing symbolic framework, we develop a causality-based characterization of distance-bounding security. This constitutes the first symbolic property that guarantees physical proximity without modeling continuous time or physical location. We extend further our formalism in order to capture a non-standard attack known as terrorist fraud. By using our definitions and the verification tool Tamarin, we conduct a security survey of over 25 protocols, which include industrial protocols based on the ISO/IEC 14443 standard such as NXP's MIFARE Plus with proximity check and Mastercard's PayPass payment protocol. For the industrial protocols we find attacks, propose fixes and deliver security proofs of the repaired versions

Security and privacy in RFID systems

RFID is a leading technology that has been rapidly deployed in several daily life applications such as payment, access control, ticketing, e-passport, supply-chain, etc. An RFID tag is an electronic label that can be attached to an object/individual in order to identify or track the object/individual through radio waves. Security and privacy are two major concerns in several applications as the tags are required to provide a proof of identity. The RFID tags are generally not tamper-resistant against strong adversarial attacks. They also have limited computational resources. Therefore, the design of a privacy preserving and cost-effective RFID authentication protocol is a very challenging task for industrial applications. Moreover, RFID systems are also vulnerable to relay attacks (i.e., mafia, terrorist and distance frauds) when they are used for authentication purposes. Distance bounding protocols are particularly designed as a countermeasure against these attacks. These protocols aim to ensure that the tags are in a bounded area by measuring the round-trip delays during a rapid challenge-response exchange of short authentication messages. Several RFID distance bounding protocols have been proposed recently in the literature. However, none of them provides the ideal security against the terrorist fraud. Besides, the requirements of low resources and inefficient data management trigger to make use of cloud computing technology in RFID authentication systems. However, as more and more information on individuals and companies is placed in the cloud, concerns about data safety and privacy raise. Therefore, while integrating cloud services into RFID authentication systems, the privacy of tag owner against the cloud must also be taken into account. Motivated by this need, this dissertation contributes to the design of algorithms and protocols aimed at dealing with the issues explained above. First of all, we introduce two privacy models for RFID authentication protocols based on Physically Unclonable Functions (PUF). We propose several authentication protocols in order to demonstrate these models. Moreover, we study distance bounding protocols having bit-wise fast phases and no final signature. We give analysis for the optimal security limits of the distance bounding protocols. Furthermore, we propose a novel RFID distance bounding protocol based on PUFs and it satisfies the highest security levels. Finally, we provide a new security and privacy model for integrating cloud computing into RFID systems. For the sake of demonstration of this model, we also propose two RFID authentication protocols that require various computational resources and provide different privacy levels

Time, computational complexity, and probability in the analysis of distance-bounding protocols

Many security protocols rely on the assumptions on the physical properties in which its protocol sessions will be carried out. For instance, Distance Bounding Protocols take into account the round trip time of messages and the transmission velocity to infer an upper bound of the distance between two agents. We classify such security protocols as Cyber-Physical. Time plays a key role in design and analysis of many of these protocols. This paper investigates the foundational differences and the impacts on the analysis when using models with discrete time and models with dense time. We show that there are attacks that can be found by models using dense time, but not when using discrete time. We illustrate this with an attack that can be carried out on most Distance Bounding Protocols. In this attack, one exploits the execution delay of instructions during one clock cycle to convince a verifier that he is in a location different from his actual position. We additionally present a probabilistic analysis of this novel attack. As a formal model for representing and analyzing Cyber-Physical properties, we propose a Multiset Rewriting model with dense time suitable for specifying cyber-physical security protocols. We introduce Circle-Configurations and show that they can be used to symbolically solve the reachability problem for our model, and show that for the important class of balanced theories the reachability problem is PSPACE-complete. We also show how our model can be implemented using the computational rewriting tool Maude, the machinery that automatically searches for such attacks

Time, computational complexity, and probability in the analysis of distance-bounding protocols

Many security protocols rely on the assumptions on the physical properties in which its protocol sessions will be carried out. For instance, Distance Bounding Protocols take into account the round trip time of messages and the transmission velocity to infer an upper bound of the distance between two agents. We classify such security protocols as Cyber-Physical. Time plays a key role in design and analysis of many of these protocols. This paper investigates the foundational differences and the impacts on the analysis when using models with discrete time and models with dense time. We show that there are attacks that can be found by models using dense time, but not when using discrete time. We illustrate this with an attack that can be carried out on most Distance Bounding Protocols. In this attack, one exploits the execution delay of instructions during one clock cycle to convince a verifier that he is in a location different from his actual position. We additionally present a probabilistic analysis of this novel attack. As a formal model for representing and analyzing Cyber-Physical properties, we propose a Multiset Rewriting model with dense time suitable for specifying cyber-physical security protocols. We introduce Circle-Configurations and show that they can be used to symbolically solve the reachability problem for our model, and show that for the important class of balanced theories the reachability problem is PSPACE-complete. We also show how our model can be implemented using the computational rewriting tool Maude, the machinery that automatically searches for such attacks

So near and yet so far - Symbolic verification of distance-bounding protocols

International audienceThe rise of new technologies, and in particular Near Field Communication (NFC) tags, offers new applications such as contactless payments, key-less entry systems, transport ticketing. .. Due to their security concerns, new security protocols, called distance-bounding protocols, have been developed to ensure physical proximity of the devices during a session. In order to prevent flaws and attacks, these protocols require formal verification. In this paper, we propose a new symbolic model allowing us to take into account the location of the agents and to model the fact that transmitting a message takes time. We propose two reduction results to render automatic verification possible relying on the existing verification tool ProVerif. Then, we perform a comprehensive case studies analysis (more than 25 protocols) relying on our new framework and its integration in ProVerif. We obtain new proofs of security for some protocols and detect attacks on some others

Optimal security limits of RFID distance bounding protocols

In this paper, we classify the RFID distance bounding protocols having bitwise fast phases and no final signature. We also give the theoretical security bounds for two specific classes, leaving the security bounds for the general case as an open problem. As for the classification, we introduce the notion of k-previous challenge dependent (k-PCD) protocols where each response bit depends on the current and k-previous challenges and there is no final signature. We treat the case k = 0, which means each response bit depends only on the current challenge, as a special case and define such protocols as current challenge dependent (CCD) protocols. In general, we construct a trade-off curve between the security levels of mafia and distance frauds by introducing two generic attack algorithms. This leads to the conclusion that CCD protocols cannot attain the ideal security against distance fraud, i.e. 1/2, for each challenge-response bit, without totally losing the security against mafia fraud. We extend the generic attacks to 1-PCD protocols and obtain a trade-off curve for 1-PCD protocols pointing out that 1-PCD protocols can provide better security than CCD protocols. Thereby, we propose a natural extension of a CCD protocol to a 1-PCD protocol in order to improve its security. As a study case, we give two natural extensions of Hancke and Kuhn protocol to show how to enhance the security against either mafia fraud or distance fraud without extra cost

A framework for analyzing RFID distance bounding protocols

Many distance bounding protocols appropriate for the RFID technology have been proposed recently. Unfortunately, they are commonly designed without any formal approach, which leads to inaccurate analyzes and unfair comparisons. Motivated by this need, we introduce a unied framework that aims to improve analysis and design of distance bounding protocols. Our framework includes a thorough terminology about the frauds, adversary, and prover, thus disambiguating many misleading terms. It also explores the adversary's capabilities and strategies, and addresses the impact of the prover's ability to tamper with his device. It thus introduces some new concepts in the distance bounding domain as the black-box and white-box models, and the relation between the frauds with respect to these models. The relevancy and impact of the framework is nally demonstrated on a study case: Munilla-Peinado distance bounding protocol