4,402 research outputs found

    Optimal Proximity Proofs Revisited

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    Distance bounding protocols become important since wireless technologies become more and more common. Therefore, the security of the distance bounding protocol should be carefully analyzed. However, most of the protocols are not secure or their security is proven informally. Recently, Boureanu and Vaudenay defined the common structure which is commonly followed by most of the distance bounding protocols: answers to challenges are accepted if they are correct and on time. They further analyzed the optimal security that we can achieve in this structure and proposed DBopt which reaches the optimal security bounds. In this paper, we define three new structures: when the prover registers the time of a challenge, when the verifier randomizes the sending time of the challenge, and the combined structure. Then, we show the optimal security bounds against distance fraud and mafia fraud which are lower than the bounds showed by Boureanu and Vaudenay for the common structure. Finally, we adapt the DBopt protocol according to our new structures and we get three new distance bounding protocols. All of them are proven formally. In the end, we compare the performance of the new protocols with DBopt and we see that we have a better efficiency. For instance, we can reduce the number of rounds in DB2 (one of the instances of DBopt) from 123 123 to 5 5 with the same security

    A Declarative Semantics for CLP with Qualification and Proximity

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    Uncertainty in Logic Programming has been investigated during the last decades, dealing with various extensions of the classical LP paradigm and different applications. Existing proposals rely on different approaches, such as clause annotations based on uncertain truth values, qualification values as a generalization of uncertain truth values, and unification based on proximity relations. On the other hand, the CLP scheme has established itself as a powerful extension of LP that supports efficient computation over specialized domains while keeping a clean declarative semantics. In this paper we propose a new scheme SQCLP designed as an extension of CLP that supports qualification values and proximity relations. We show that several previous proposals can be viewed as particular cases of the new scheme, obtained by partial instantiation. We present a declarative semantics for SQCLP that is based on observables, providing fixpoint and proof-theoretical characterizations of least program models as well as an implementation-independent notion of goal solutions.Comment: 17 pages, 26th Int'l. Conference on Logic Programming (ICLP'10

    Strong ETH Breaks With Merlin and Arthur: Short Non-Interactive Proofs of Batch Evaluation

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    We present an efficient proof system for Multipoint Arithmetic Circuit Evaluation: for every arithmetic circuit C(x1,
,xn)C(x_1,\ldots,x_n) of size ss and degree dd over a field F{\mathbb F}, and any inputs a1,
,aK∈Fna_1,\ldots,a_K \in {\mathbb F}^n, ∙\bullet the Prover sends the Verifier the values C(a1),
,C(aK)∈FC(a_1), \ldots, C(a_K) \in {\mathbb F} and a proof of O~(K⋅d)\tilde{O}(K \cdot d) length, and ∙\bullet the Verifier tosses poly(log⁥(dK∣F∣/Δ))\textrm{poly}(\log(dK|{\mathbb F}|/\varepsilon)) coins and can check the proof in about O~(K⋅(n+d)+s)\tilde{O}(K \cdot(n + d) + s) time, with probability of error less than Δ\varepsilon. For small degree dd, this "Merlin-Arthur" proof system (a.k.a. MA-proof system) runs in nearly-linear time, and has many applications. For example, we obtain MA-proof systems that run in cnc^{n} time (for various c<2c < 2) for the Permanent, #\#Circuit-SAT for all sublinear-depth circuits, counting Hamiltonian cycles, and infeasibility of 00-11 linear programs. In general, the value of any polynomial in Valiant's class VP{\sf VP} can be certified faster than "exhaustive summation" over all possible assignments. These results strongly refute a Merlin-Arthur Strong ETH and Arthur-Merlin Strong ETH posed by Russell Impagliazzo and others. We also give a three-round (AMA) proof system for quantified Boolean formulas running in 22n/3+o(n)2^{2n/3+o(n)} time, nearly-linear time MA-proof systems for counting orthogonal vectors in a collection and finding Closest Pairs in the Hamming metric, and a MA-proof system running in nk/2+O(1)n^{k/2+O(1)}-time for counting kk-cliques in graphs. We point to some potential future directions for refuting the Nondeterministic Strong ETH.Comment: 17 page

    Separable Convex Optimization with Nested Lower and Upper Constraints

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    We study a convex resource allocation problem in which lower and upper bounds are imposed on partial sums of allocations. This model is linked to a large range of applications, including production planning, speed optimization, stratified sampling, support vector machines, portfolio management, and telecommunications. We propose an efficient gradient-free divide-and-conquer algorithm, which uses monotonicity arguments to generate valid bounds from the recursive calls, and eliminate linking constraints based on the information from sub-problems. This algorithm does not need strict convexity or differentiability. It produces an Ï”\epsilon-approximate solution for the continuous problem in O(nlog⁥mlog⁥nBÏ”)\mathcal{O}(n \log m \log \frac{n B}{\epsilon}) time and an integer solution in O(nlog⁥mlog⁥B)\mathcal{O}(n \log m \log B) time, where nn is the number of decision variables, mm is the number of constraints, and BB is the resource bound. A complexity of O(nlog⁥m)\mathcal{O}(n \log m) is also achieved for the linear and quadratic cases. These are the best complexities known to date for this important problem class. Our experimental analyses confirm the good performance of the method, which produces optimal solutions for problems with up to 1,000,000 variables in a few seconds. Promising applications to the support vector ordinal regression problem are also investigated

    A framework for analyzing RFID distance bounding protocols

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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 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
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