Private function evaluation aims to securely compute a function$f(x_1, \ldots, x_n)$without leaking any information other than what is revealed by the output, where$f$is a private input of one of the parties (say$\mathsf {Party}_1$) and$x_i$is a private input of the$i$th party$\mathsf {Party}_i$. In this article, we propose a novel and securetwo-party private function evaluation(2PFE) scheme based on the DDH assumption. Our scheme introduces a reusability feature that significantly improves the state-of-the-art. Accordingly, our scheme has two variants, one is utilized in the initial execution of the function$f$, and the other is utilized in its subsequent evaluations. To the best of our knowledge, this is the first and most efficient 2PFE scheme that enjoys a reusablity feature. Our protocols achieve linear communication and computation complexities and a constant number of rounds which is at most three.

Private function evaluation (PFE) is a special case of secure multi-party computation (MPC), where the function to be computed is known by only one party. PFE is useful in several real-life applications where an algorithm or a function itself needs to remain secret for reasons such as protecting intellectual property or security classification level. In this paper, we focus on improving 2-party PFE based on symmetric cryptographic primitives. In this respect, we look back at the seminal PFE framework presented by Mohassel and Sadeghian at Eurocrypt’13. We show how to adapt and utilize the well-known half gates garbling technique (Zahur et al., Eurocrypt’15) to their constant-round 2-party PFE scheme. Compared to their scheme, our resulting optimization significantly improves the efficiency of both the underlying Oblivious Evaluation of Extended Permutation (OEP) and secure 2-party computation (2PC) protocols, and yields a more than 40% reduction in overall communication cost (the computation time is also slightly decreased and the number of rounds remains unchanged).

Abstract Norway experienced internet voting in 2011 and 2013 for municipal and parliamentary elections, respectively. Its security depends on the assumptions that the involving organizations are completely independent, reliable, and the receipt codes are securely sent to the voters. In this paper, we point out the following aspects: The vote privacy of the Norwegian scheme is violated if Ballot Box and Receipt Generator cooperate because the private key of Decryption Service can be obtained by the two former players. We propose a solution to avoid this issue without adding new players. To assure the correctness, the receipt codes are sent to the voters over a pre‐channel (postal service) and a post‐channel (Short Message Service [SMS]). However, by holding both SMS and the postal receipt code, a voter can reveal his vote even after the elections. Albeit revoting is a fairly well solution for coercion or concealment, intentional vote revealing is still a problem. We suggest SMS only for notification of vote submission. In case the codes are falsely generated or the pre‐channel is not secure, a vote can be counted for a different candidate without detection. We propose a solution in which voters verify the integrity of the postal receipt codes. Copyright © 2016 John Wiley & Sons, Ltd.

Abstract This paper examines Vaudenay's privacy model, which is one of the first and most complete privacy models that featured the notion of different privacy classes. We enhance this model by introducing two new generic adversary classes,k‐strong andk‐forward adversaries where the adversary is allowed to corrupt a tag at mostktimes. Moreover, we introduce an extended privacy definition that also covers all privacy classes of Vaudenay's model. In order to achieve highest privacy level, we study low cost primitives such as physically unclonable functions (PUFs). The common assumption of PUFs is that their physical structure is destroyed once tampered. This is an ideal assumption because the tamper resistance depends on the ability of the attacker and the quality of the PUF circuits. In this paper, we have weakened this assumption by introducing a new definitionk‐resistant PUFs.k‐PUFs are tamper resistant against at mostkattacks; that is, their physical structure remains still functional and correct until at mostkthphysical attack. Furthermore, we prove that strong privacy can be achieved without public‐key cryptography usingkPUF‐based authentication. We finally prove that our extended proposal achieves both reader authentication andk‐strong privacy. Copyright © 2014 John Wiley & Sons, Ltd.

RFID is a leading technology that has been rapidly deployed in several daily life applications that require strong security and privacy mechanisms. However, RFID systems commonly have limited computational capacity and inefficient data management. There is a demanding urge to address these issues in the light of some mechanism which can make the technology excel. Cloud computing is one of the fastest growing segments of IT industry that provides cost effective solutions for handling and using data collected with RFID. As more and more information on companies and individuals is placed in the cloud, concerns are beginning to escalate about just how safe an environment it is. Therefore, while integrating RFID into the cloud, the security and privacy of the tag owner must be considered. Motivated by this, we first provide a new security and privacy model for RFID technology integrated to the cloud computing. In this model, we define the capabilities of the adversary and give the formal definitions. After that we propose a cloud-based RFID authentication protocol to illustrate our model. The protocol utilizes symmetric-key based cryptography. We prove that the protocol achieves destructive privacy according to our model.

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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 unified framework that aims to i mprove 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 finally demonstrated on a study case: Munilla–Peinado distance bounding protocol.