Security and Privacy in RFID Systems

This PhD thesis is concerned with authentication protocols using portable lightweight devices such as RFID tags. these devices have lately gained a significant attention for the diversity of the applications that could benefit form their features, ranging from inventory systems and building access control, to medical devices. However, the emergence of this technology has raised concerns about the possible loss of privacy carrying such tags induce in allowing tracing persons or unveiling the contents of a hidden package. this fear led to the appearance of several organizations which goal is to stop the spread of RFID tags. We take a cryptographic viewpoint on the issue and study the extent of security and privacy that RFID-based solutions can offer. In the first part of this thesis, we concentrate on analyzing two original primitives that were proposed to ensure security for RFID tags. the first one, HB#, is a dedicated authentication protocol that exclusively uses very simple arithmetic operations: bitwise AND and XOR. HB# was proven to be secure against a certain class of man-in-the-middle attacks and conjectured secure against more general ones. We show that the latter conjecture does not hold by describing a practical attack that allows an attacker to recover the tag's secret key. Moreover, we show that to be immune against our attack, HB#'s secret key size has to be increased to be more than 15 000 bits. this is an unpractical value for the considered applications. We then turn to SQUASH, a message authentication code built around a public-key encryption scheme, namely Rabin's scheme. By mounting a practical key recovery attack on the earlier version of SQUASH, we show that the security of all versions of SQUASH is unrelated to the security of Rabin encryption function. The second part of the thesis is dedicated to the privacy aspects related to the RFID technology. We first emphasize the importance of establishing a framework that correctly captures the intuition that a privacy-preserving protocol does not leak any information about its participants. For that, we show how several protocols that were supported by simple arguments, in contrast to a formal analysis, fail to ensure privacy. Namely, we target ProbIP, MARP, Auth2, YA-TRAP, YA-TRAP+, O-TRAP, RIPP-FS, and the Lim-Kwon protocol. We also illustrate the shortcomings of other privacy models such as the LBdM model. The rest of the dissertation is then dedicated to our privacy model. Contrarily to most RFID privacy models that limit privacy protection to the inability of linking the identity of two participants in two different protocol instances, we introduce a privacy model for RFID tags that proves to be the exact formalization of the intuition that a private protocol should not leak any information to the adversary. the model we introduce is a refinement of Vaudenay's one that invalidates a number of its limitations. Within these settings, we are able to show that the strongest notion of privacy, namely privacy against adversaries that have a prior knowledge of all the tags' secrets, is realizable. To instantiate an authentication protocol that achieves this level of privacy, we use plaintext-aware encryption schemes. We then extend our model to the case of mutual authentication where, in addition to a tag authenticating to the reader, the reverse operation is also required

Forgery-Resilience for Digital Signature Schemes

We introduce the notion of forgery-resilience for digital signature schemes, a new paradigm for digital signature schemes exhibiting desirable legislative properties. It evolves around the idea that, for any message, there can only be a unique valid signature, and exponentially many acceptable signatures, all but one of them being spurious. This primitive enables a judge to verify whether an alleged forged signature is indeed a forgery. In particular, the scheme considers an adversary who has access to a signing oracle and an oracle that solves a “hard” problem, and who tries to produce a signature that appears to be acceptable from a verifier’s point of view. However, a judge can tell apart such a spurious signature from a signature that is produced by an honest signer. This property is referred to as validatibility. Moreover, the scheme provides undeniability against malicious signers who try to fabricate spurious signatures and deny them later by showing that they are not valid. Last but not least, trustability refers to the inability of a malicious judge trying to forge a valid signature. This notion for signature schemes improves upon the notion of fail-stop signatures in different ways. For example, it is possible to sign more than one messages with forgery-resilient signatures and once a forgery is found, the credibility of a previously signed signature is not under question. A concrete instance of a forgery-resilient signature scheme is constructed based on the hardness of extracting roots of higher residues, which we show to be equivalent to the factoring assumption. In particular, using collision-free accumulators, we present a tight reduction from malicious signers to adversaries against the factoring problem. Meanwhile, a secure pseudorandom function ensures that no polynomially-bounded cheating verifier, who can still solve hard problems, is able to forge valid signatures. Security against malicious judges is based on the RSA assumption

Pathchecker: An RFID application for tracing products in Supply-chains

In this paper, we present an application of RFIDs for supply-chain management. In our application, we consider two types of readers. On one part, we have readers that will mark tags at given points. After that, these tags can be checked by another type of readers to tell whether a tag has followed the correct path in the chain. We formalize this notion and define adequate adversaries. Morever, we derive requirements in order to meet security against counterfeiting, cloning, impersonation and denial of service attacks

Privacy of Recent RFID Authentication Protocols

Privacy is a major concern in RFID systems, especially with widespread deployment of wireless-enabled interconnected personal devices e.g. PDAs and mobile phones, credit cards, e-passports, even clothing and tires. An RFID authentication protocol should not only allow a legitimate reader to authenticate a tag but it should also protect the privacy of the tag against unauthorized tracing: an adversary should not be able to get any useful information about the tag for tracking or discovering the tag’s identity. In this paper, we analyze the privacy of some recently proposed RFID authentication protocols (2006 and 2007) and show attacks on them that compromise their privacy. Our attacks consider the simplest adversaries that do not corrupt nor open the tags. We describe our attacks against a general untraceability model; from experience we view this endeavour as a good practice to keep in mind when designing and analyzing security protocols

Privacy analysis of forward and backward untraceable RFID authentication schemes

In this paper, we analyze the rst known provably secure RFID authentication schemes that are designed to provide forward untraceability and backward untraceability: the L-K and S-M schemes. We show how to trace tags in the L-K scheme without needing to corrupt tags. We also show that if a standard cryptographic pseudorandom bit generator (PRBG) is used in the S-M scheme, then the scheme may fail to provide forward untraceability and backward untraceability. To achieve the desired untraceability features, we show that the S-M scheme can use a robust PRBG which provides forward security and backward security. We also note that the backward security is stronger than necessary for the backward untraceability of the S-M scheme

Note de conférence: introduction aux calculateurs quantiques

<p>Introduction paper to quantum computing.</p

Pathchecker: an RFID Application for Tracing Products in Suply-Chains ⋆

Abstract. In this paper, we present an application of RFIDs for supplychain management. In our application, we consider two types of readers. On one part, we have readers that will mark tags at given points. After that, these tags can be checked by another type of readers to tell whether a tag has followed the correct path in the chain. We formalize this notion and define adequate adversaries. Morever, we derive requirements in order to meet security against counterfeiting, cloning, impersonation and denial of service attacks.

Application of Classical Compound-Poisson Risk Models in Barrier Strategies

<p>In this paper, we propose a discrete-time counterpart of the classical compound Poisson and several applications of a bivariate extension of the Dickson-Waters discretisation. We expose numerous examples, including forth-looking scenario of ruin and surplus models</p

Smashing SQUASH-0

a new challenge-response protocol well suited for RFIDs, although based on the Rabin public-key cryptosystem. This protocol, which we call SQUASH-0, was using a linear mixing function which was subsequently withdrawn. Essentially, we mount an attack against SQUASH-0 with full window which could be used as a “known random coins attack ” against Rabin-SAEP. We then extend it for SQUASH-0 with arbitrary window. We apply it with the proposed modulus 2 1 277 − 1 to run a key recovery attack using 1 024 chosen challenges. Since the security arguments equally apply to the final version of SQUASH and to SQUASH-0, we challenge the blame-game argument for the security of SQUASH. Nevertheless, our attacks are inefficient when using non-linear mixing so the security of SQUASH remains open