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Agrawal S.,University of California at Los Angeles | Dodis Y.,NYU | Vaikuntanathan V.,U. Toronto | Wichs D.,Northeastern U.
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

Let double-struck G be a group of prime order q, and let g 1,...,gn be random elements of double-struck G. We say that a vector x = (x1,...,x2) ∈ ℤ q n is a discrete log representation of some some element y ∈ double-struck G (with respect to g1,...,gn) if g1 x1⋯gn xn = y. Any element y has many discrete log representations, forming an affine subspace of ℤq n. We show that these representations have a nice continuous leakage-resilience property as follows. Assume some attacker A(g 1,...,gn, y) can repeatedly learn L bits of information on arbitrarily many random representations of y. That is, A adaptively chooses polynomially many leakage functions fi : ℤq n → {0,1}L, and learns the value fi(x i), where xi is a fresh and random discrete log representation of y. A wins the game if it eventually outputs a valid discrete log representation x* of y. We show that if the discrete log assumption holds in double-struck G, then no polynomially bounded A can win this game with non-negligible probability, as long as the leakage on each representation is bounded by L ≈ (n - 2) log q = (1 - 2/n)·|x|. As direct extensions of this property, we design very simple continuous leakage-resilient (CLR) one-way function (OWF) and public-key encryption (PKE) schemes in the so called "invisible key update" model introduced by Alwen et al. at CRYPTO'09. Our CLR-OWF is based on the standard Discrete Log assumption and our CLR-PKE is based on the standard Decisional Diffie-Hellman assumption. Prior to our work, such schemes could only be constructed in groups with a bilinear pairing. As another surprising application, we show how to design the first leakage-resilient traitor tracing scheme, where no attacker, getting the secret keys of a small subset of decoders (called "traitors") and bounded leakage on the secret keys of all other decoders, can create a valid decryption key which will not be traced back to at least one of the traitors. © 2013 Springer-Verlag.


Cousot P.,NYU | Cousot R.,French Institute for Research in Computer Science and Automation | Fahndrich M.,Microsoft | Logozzo F.,Microsoft
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

We consider the problem of automatic precondition inference. We argue that the common notion of sufficient precondition inference (i.e., under which precondition is the program correct?) imposes too large a burden on callers, and hence it is unfit for automatic program analysis. Therefore, we define the problem of necessary precondition inference (i.e., under which precondition, if violated, will the program always be incorrect?). We designed and implemented several new abstract interpretation-based analyses to infer atomic, disjunctive, universally and existentially quantified necessary preconditions. We experimentally validated the analyses on large scale industrial code. For unannotated code, the inference algorithms find necessary preconditions for almost 64% of methods which contained warnings. In 27% of these cases the inferred preconditions were also sufficient, meaning all warnings within the method body disappeared. For annotated code, the inference algorithms find necessary preconditions for over 68% of methods with warnings. In almost 50% of these cases the preconditions were also sufficient. Overall, the precision improvement obtained by precondition inference (counted as the additional number of methods with no warnings) ranged between 9% and 21%. © Springer-Verlag 2013.


Kashuk S.,National Oceanic and Atmospheric Administration | Iskander M.,NYU
Computers and Geosciences | Year: 2015

This paper presents a method for predicting positions of color cubes inside a square transparent solid object from images taken at the orthogonal boundary surfaces. The work is developed for use in mapping flow of non-aqueous phase liquids (NAPL) in transparent soils. Transparent soil models have been developed to study the flow of contaminants through porous media, in bench scale tests. Yellow transparent cubes are used to represent NAPL plumes and clear transparent cubes are used as representations of transparent soil in order to definitively validate the algorithm. Color space information is used to relate concentration and image intensity. The new algorithm employs a so-called 3D carving method to iteratively reconstruct a 3D model using images taken at three orthogonal boundaries. The methodology presented in this paper is a fast, relatively accurate, non-intrusive and inexpensive method for quantifying NAPL zones in transparent soil models. © 2015 Elsevier Ltd.


Khot S.,NYU | Safra M.,Tel Aviv University | Tulsiani M.,TTI Chicago
ITCS 2013 - Proceedings of the 2013 ACM Conference on Innovations in Theoretical Computer Science | Year: 2013

We construct a PCP based on the hyper-graph linearity test with 3 free queries. It has near-perfect completeness and soundness strictly less than 1/8. Such a PCP was known before only assuming the Unique Games Conjecture, albeit with soundness arbitrarily close to 1/16. At a technical level, our main contribution is constructing a new outer PCP which is "robust" against bounded degree polynomials, and showing that it can be composed with the hyper-graph linearity test with 3 free queries. We believe this outer PCP may be useful in obtaining the optimal query vs. soundness tradeoff for PCPs. © 2013 ACM.


Cicconet M.,NYU | Geiger D.,NYU | Gunsalus K.C.,NYU | Werman M.,Hebrew University
Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition | Year: 2014

We propose a data structure that captures global geometric properties in images: Histogram of Mirror Symmetry Coefficients. We compute such a coefficient for every pair of pixels, and group them in a 6-dimensional histogram. By marginalizing the HMSC in various ways, we develop algorithms for a range of applications: detection of nearly-circular cells, location of the main axis of reflection symmetry, detection of cell-division in movies of developing embryos, detection of worm-tips and indirect cell-counting via supervised classification. Our approach generalizes a series of histogram-related methods, and the proposed algorithms perform with state-of-the-art accuracy. © 2014 IEEE.


Aggarwal D.,Ecole Polytechnique Federale de Lausanne | Dodis Y.,NYU | Kazana T.,NYU | Obremski M.,University of Warsaw
Proceedings of the Annual ACM Symposium on Theory of Computing | Year: 2015

Non-malleable codes, introduced by Dziembowski, Pietrzak and Wichs [DPW10], provide a useful message integrity guarantee in situations where traditional error-correction (and even error-detection) is impossible; for example, when the attacker can completely overwrite the encoded message. Informally, a code is non-malleable if the message contained in a modified codeword is either the original message, or a completely "unrelated value". Although such codes do not exist if the family of "tampering functions" F allowed to modify the original codeword is completely unrestricted, they are known to exist for many broad tampering families F. The family which received the most attention [DPW10, LL12, DKO13, ADL14, CG14a, CG14b] is the family of tampering functions in the so called (2-part) split-state model: here the message x is encoded into two shares L and R, and the attacker is allowed to arbitrarily tamper with each L and R individually. Despite this attention, the following problem remained open: Build efficient, information-theoretically secure non-malleable codes in the split-state model with constant encoding rate: |L| = |R| = O(|x|). In this work, we resolve this open problem. Our technique for getting our main result is of independent interest. We (a) develop a generalization of non-malleable codes, called non-malleable reductions; (b) show simple composition theorem for non-malleable reductions; (c) build a variety of such reductions connecting various (independently interesting) tampering families F to each other; (d) construct several new non-malleable codes in the split-state model by applying the composition theorem to a series of easy to understand reductions. Most importantly, we show several "independence amplification" reductions, showing how to reduce split-state tampering of very few parts to an easier question of split-state tampering with a much larger number of parts. In particular, our final, constant-rate, non-malleable code composes one of these reductions with the very recent, "9-split-state" code of Chattopadhyay and Zuckerman [CZ14]. © Copyright 2015 ACM.


Ferreira N.,New York University | Poco J.,New York University | Vo H.T.,NYU | Freire J.,New York University | Silva C.T.,New York University
IEEE Transactions on Visualization and Computer Graphics | Year: 2013

As increasing volumes of urban data are captured and become available, new opportunities arise for data-driven analysis that can lead to improvements in the lives of citizens through evidence-based decision making and policies. In this paper, we focus on a particularly important urban data set: taxi trips. Taxis are valuable sensors and information associated with taxi trips can provide unprecedented insight into many different aspects of city life, from economic activity and human behavior to mobility patterns. But analyzing these data presents many challenges. The data are complex, containing geographical and temporal components in addition to multiple variables associated with each trip. Consequently, it is hard to specify exploratory queries and to perform comparative analyses (e.g., compare different regions over time). This problem is compounded due to the size of the data-there are on average 500,000 taxi trips each day in NYC. We propose a new model that allows users to visually query taxi trips. Besides standard analytics queries, the model supports origin-destination queries that enable the study of mobility across the city. We show that this model is able to express a wide range of spatio-temporal queries, and it is also flexible in that not only can queries be composed but also different aggregations and visual representations can be applied, allowing users to explore and compare results. We have built a scalable system that implements this model which supports interactive response times; makes use of an adaptive level-of-detail rendering strategy to generate clutter-free visualization for large results; and shows hidden details to the users in a summary through the use of overlay heat maps. We present a series of case studies motivated by traffic engineers and economists that show how our model and system enable domain experts to perform tasks that were previously unattainable for them. © 1995-2012 IEEE.


Kannan S.,New York University | Karimi N.,New York University | Sinanoglu O.,NYU
Proceedings - Design Automation Conference | Year: 2014

Non-volatile memory devices such as phase change mem-ories and memristors are promising alternatives to SRAM and DRAM main memories as they provide higher den-sity and improved energy effciency. However, non-volatile main memories (NVMM) introduce security vulnerabilities. Sensitive data such as passwords and keys residing in the NVMM will persist and can be probed after power down. We propose sneak-path encryption (SPE), for memristor-based NVMM. SPE exploits the physical parameters, multi-level cell (MLC) capability and the sneak paths in cross-bar memories to encrypt the data stored in memristor-based NVMM. We investigate three attacks on NVMMs and show the resilience of SPE against them. We use a cycle accurate simulator to evaluate the security and performance impact of SPE based NVMM. SPE can secure the NVMM with a latency of 16 cycles and ̃1.5% performance overhead. Copyright 2014 ACM.


Levy-Warren M.H.,NYU
Journal of Infant, Child, and Adolescent Psychotherapy | Year: 2014

This discussion of Christogiorgios and Gianna Kopoulos’ fine case, “School Refusal and the Parent-Child Relationship: A Psychodynamic Perspective,” focuses on the young adolescent’s overall development during his emotional crisis. I pay particular attention to the patient, Peter’s, growth as a young man, his relationship to other males—including his father, and his anxious engagement with his peers. My purpose is to contextualize the clinical work within the larger fabric of Peter’s life. Copyright © Taylor & Francis Group, LLC.


Parent B.,NYU
Hastings Center Report | Year: 2014

Recent policy changes enacted by the Organ Procurement and Transplantation Network designate faces as organs for the purposes of donation and transplantation. The OPTN policy includes no requirement that donors be made aware that faces are among donatable parts, but it does require specific consent to face donation (not just organ donation in general) from either the donor or donor's family before a face can be transplanted. If you are a registered donor and you do not record your refusal, your family might be approached for your face. If your next of kin says yes, your face will be donated. On the other side, if you do want to donate your face and have recorded your specific consent, but your family says no, tough luck. Should families have greater control than donors over the disposition of the donors' faces? © 2014 The Hastings Center.

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