Periodic harmonic functions on lattices and points count in positive characteristic

This survey addresses pluri-periodic harmonic functions on lattices with values in a positive characteristic field. We mention, as a motivation, the game "Lights Out" following the work of Sutner, Goldwasser-Klostermeyer-Ware, Barua-Ramakrishnan-Sarkar, Hunzikel-Machiavello-Park e.a.; see also 2 previous author's preprints for a more detailed account. Our approach explores harmonic analysis and algebraic geometry over a positive characteristic field. The Fourier transform allows us to interpret pluri-periods of harmonic functions on lattices as torsion multi-orders of points on the corresponding affine algebraic variety.Comment: These are notes on 13p. based on a talk presented during the meeting "Analysis on Graphs and Fractals", the Cardiff University, 29 May-2 June 2007 (a sattelite meeting of the programme "Analysis on Graphs and its Applications" at the Isaac Newton Institute from 8 January to 29 June 2007

A Framework for Evaluating Security in the Presence of Signal Injection Attacks

Sensors are embedded in security-critical applications from medical devices to nuclear power plants, but their outputs can be spoofed through electromagnetic and other types of signals transmitted by attackers at a distance. To address the lack of a unifying framework for evaluating the effects of such transmissions, we introduce a system and threat model for signal injection attacks. We further define the concepts of existential, selective, and universal security, which address attacker goals from mere disruptions of the sensor readings to precise waveform injections. Moreover, we introduce an algorithm which allows circuit designers to concretely calculate the security level of real systems. Finally, we apply our definitions and algorithm in practice using measurements of injections against a smartphone microphone, and analyze the demodulation characteristics of commercial Analog-to-Digital Converters (ADCs). Overall, our work highlights the importance of evaluating the susceptibility of systems against signal injection attacks, and introduces both the terminology and the methodology to do so.Comment: This article is the extended technical report version of the paper presented at ESORICS 2019, 24th European Symposium on Research in Computer Security (ESORICS), Luxembourg, Luxembourg, September 201

Intuition in Bergson's philosophy

Thesis (M.A.)--Boston UniversityProblem. This thesis represents an attempt to understand and evaluate Bergson's doctrine of intuition, and its use in an intuitive method. Various definitions of intuition, along with a continual re-amplification of possible meanings, are scattered throughout most of Bergson's works. There are times when contradictions appear to occur. Therefore, the first goal of this thesis is an attempt to fit all of the possible meanings of intuition into a coherent scheme . In addition, for Bergson, the use of intuition implies a method, and, therefore, the second goal of this thesis is an attempt to determine of what value Bergson's intuitional method is to philosophy. The adequacy of Bergson's intuitive method is contingent upon an adequate development of intuition and a fair critique of the limitations of the intellectual faculty. Therefore, Bergson's critique of the intellect is carefully examined. Further, while the object of intuition is duration, duration may be related to the self, to life and to matter. This thesis considers the use of intuition in these three realms. The intuition of the self. For Bergson, an intellectualist view of the self can only lead to its fragmentation. On the one hand, and particularly in An Introduction to Metaphysics, the intuition of the self appears to be a return to a felt immediacy of experience, an immediacy prior to intellection, prior to analysis. On the other hand, near the conclusion of that same work, Bergson notes that the intuition of the self can arise only after painstaking analysis. These two apparently conflicting views of intuition are strains that weave through most of Bergson's works. [truncated

Securing computation against continuous leakage

30th Annual Cryptology Conference, Santa Barbara, CA, USA, August 15-19, 2010. ProceedingsWe present a general method to compile any cryptographic algorithm into one which resists side channel attacks of the only computation leaks information variety for an unbounded number of executions. Our method uses as a building block a semantically secure subsidiary bit encryption scheme with the following additional operations: key refreshing, oblivious generation of cipher texts, leakage resilience re-generation, and blinded homomorphic evaluation of one single complete gate (e.g. NAND). Furthermore, the security properties of the subsidiary encryption scheme should withstand bounded leakage incurred while performing each of the above operations. We show how to implement such a subsidiary encryption scheme under the DDH intractability assumption and the existence of a simple secure hardware component. The hardware component is independent of the encryption scheme secret key. The subsidiary encryption scheme resists leakage attacks where the leakage is computable in polynomial time and of length bounded by a constant fraction of the security parameter.Israel Science Foundation (710267)United States-Israel Binational Science Foundation (710613)National Science Foundation (U.S.) (6914349)Weizmann KAMAR Gran

Using continuous measurement to protect a universal set of quantum gates within a perturbed decoherence-free subspace

We consider a universal set of quantum gates encoded within a perturbed decoherence-free subspace of four physical qubits. Using second-order perturbation theory and a measuring device modeled by an infinite set of harmonic oscillators, simply coupled to the system, we show that continuous observation of the coupling agent induces inhibition of the decoherence due to spurious perturbations. We thus advance the idea of protecting or even creating a decoherence-free subspace for processing quantum information.Comment: 7 pages, 1 figure. To be published in Journal of Physics A: Mathematical and Genera

Extending and Applying a Framework for the Cryptographic Verification of Java Programs

Abstract. In our previous work, we have proposed a framework which allows tools that can check standard noninterference properties but a priori cannot deal with cryptography to establish cryptographic indistinguishability properties, such as privacy properties, for Java programs. We refer to this framework as the CVJ framework (Cryptographic Verification of Java Programs) in this paper. While so far the CVJ framework directly supports public-key encryption (without corruption and without a public-key infrastructure) only, in this work we further instantiate the framework to support, among others, public-key encryption and digital signatures, both with corruption and a public-key infrastructure, as well as (private) symmetric encryption. Since these cryptographic primitives are very common in security-critical applications, our extensions make the framework much more widely applicable. To illustrate the usefulness and applicability of the extensions proposed in this paper, we apply the framework along with the tool Joana, which allows for the fully automatic verification of noninterference properties of Java programs, to establish cryptographic privacy properties of a (non-trivial) cloud storage application, where clients can store private information on a remote server.

Secret-Sharing for NP

A computational secret-sharing scheme is a method that enables a dealer, that has a secret, to distribute this secret among a set of parties such that a "qualified" subset of parties can efficiently reconstruct the secret while any "unqualified" subset of parties cannot efficiently learn anything about the secret. The collection of "qualified" subsets is defined by a Boolean function. It has been a major open problem to understand which (monotone) functions can be realized by a computational secret-sharing schemes. Yao suggested a method for secret-sharing for any function that has a polynomial-size monotone circuit (a class which is strictly smaller than the class of monotone functions in P). Around 1990 Rudich raised the possibility of obtaining secret-sharing for all monotone functions in NP: In order to reconstruct the secret a set of parties must be "qualified" and provide a witness attesting to this fact. Recently, Garg et al. (STOC 2013) put forward the concept of witness encryption, where the goal is to encrypt a message relative to a statement "x in L" for a language L in NP such that anyone holding a witness to the statement can decrypt the message, however, if x is not in L, then it is computationally hard to decrypt. Garg et al. showed how to construct several cryptographic primitives from witness encryption and gave a candidate construction. One can show that computational secret-sharing implies witness encryption for the same language. Our main result is the converse: we give a construction of a computational secret-sharing scheme for any monotone function in NP assuming witness encryption for NP and one-way functions. As a consequence we get a completeness theorem for secret-sharing: computational secret-sharing scheme for any single monotone NP-complete function implies a computational secret-sharing scheme for every monotone function in NP

Formal Verification of Security Protocol Implementations: A Survey

Automated formal verification of security protocols has been mostly focused on analyzing high-level abstract models which, however, are significantly different from real protocol implementations written in programming languages. Recently, some researchers have started investigating techniques that bring automated formal proofs closer to real implementations. This paper surveys these attempts, focusing on approaches that target the application code that implements protocol logic, rather than the libraries that implement cryptography. According to these approaches, libraries are assumed to correctly implement some models. The aim is to derive formal proofs that, under this assumption, give assurance about the application code that implements the protocol logic. The two main approaches of model extraction and code generation are presented, along with the main techniques adopted for each approac

Leakage-resilient coin tossing

Proceedings 25th International Symposium, DISC 2011, Rome, Italy, September 20-22, 2011.The ability to collectively toss a common coin among n parties in the presence of faults is an important primitive in the arsenal of randomized distributed protocols. In the case of dishonest majority, it was shown to be impossible to achieve less than 1 r bias in O(r) rounds (Cleve STOC ’86). In the case of honest majority, in contrast, unconditionally secure O(1)-round protocols for generating common unbiased coins follow from general completeness theorems on multi-party secure protocols in the secure channels model (e.g., BGW, CCD STOC ’88). However, in the O(1)-round protocols with honest majority, parties generate and hold secret values which are assumed to be perfectly hidden from malicious parties: an assumption which is crucial to proving the resulting common coin is unbiased. This assumption unfortunately does not seem to hold in practice, as attackers can launch side-channel attacks on the local state of honest parties and leak information on their secrets. In this work, we present an O(1)-round protocol for collectively generating an unbiased common coin, in the presence of leakage on the local state of the honest parties. We tolerate t ≤ ( 1 3 − )n computationallyunbounded Byzantine faults and in addition a Ω(1)-fraction leakage on each (honest) party’s secret state. Our results hold in the memory leakage model (of Akavia, Goldwasser, Vaikuntanathan ’08) adapted to the distributed setting. Additional contributions of our work are the tools we introduce to achieve the collective coin toss: a procedure for disjoint committee election, and leakage-resilient verifiable secret sharing.National Defense Science and Engineering Graduate FellowshipNational Science Foundation (U.S.) (CCF-1018064