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Abstract. In this paper, we study the problem of simultaneously achieving several security properties, for voting schemes, without non-standard assumptions. More specifically, we focus on the universal verifiability of the computation of the tally, on the unconditional privacy/anonymity of the votes, and on the receipt-freeness properties, for the most classical election processes. Under usual assumptions and efficiency requirements, we show that a voting system that wants to publish the final list of the voters who actually voted, and to compute the number of times each candidate has been chosen, we cannot achieve:-universal verifiability of the tally (UV) and unconditional privacy of the votes (UP) simultaneously, unless all the registered voters actually vote;

IEEE Communications Surveys and Tutorials, à paraître.International audienceMachine-to-Machine (M2M) is one of the emergent technologies that has attracted a lot of attention in both industrial and academic sectors and which is expected to grow in the next few years. Indeed, it opens the way to the Internet of Things (IoT), an internet where all devices are connected and communicate without any human intervention. Yet, an important hurdle that may slow down Machine-to-Machine growth and even hinder the massive roll-out of certain applications is security. Even though there have been a lot of research on Machine-to-Machine, nevertheless only few of them focus on the security aspects. As a fusion of heterogeneous networks, Machine-to-Machine poses a number of challenges, particularly to security design. In this paper, we provide a survey on Machine-to-Machine research and development works that mainly addresses security and more precisely the threats that Machine-to-Machine communications have to face. We also tackle the challenges that arise when trying to secure M2M communications along with an investigation of the existing approaches aiming to do so. Finally, we give a general comparison of existing solutions regarding some selected parameters

International audienceDivisible e-cash systems allow users to withdraw a unique coin of value 2 n units from a bank, but then to spend it in several times to distinct merchants. In such a system, whereas users want anonymity of their transactions, the bank wants to prevent, or at least detect, double-spending, and trace defrauders. While this primitive was introduced two decades ago, quite a few (really) anonymous constructions have been proposed. In addition, all but one were just proven secure in the random oracle model, but still with either weak security models or quite complex settings and thus costly constructions. The unique proposal, secure in the standard model, appeared recently and is unpractical. As evidence, the authors left the construction of an efficient scheme secure in this model as an open problem. In this study, the authors answer it with the first efficient divisible e-cash system secure in the standard model. It is based on a new way of building the coins, with a unique and public global tree structure for all the coins. Actually, they propose two constructions which offer a tradeoff between efficiency and security. They both achieve constant time for withdrawing and spending amounts of 2ℓ units, while allowing the bank to quickly detect double-spendings by a simple comparison of the serial numbers of deposited coins to the ones of previously spent coins