TY - JOUR AB - We introduce the notion of “non-malleable codes” which relaxes the notion of error correction and error detection. Informally, a code is non-malleable if the message contained in a modified codeword is either the original message, or a completely unrelated value. In contrast to error correction and error detection, non-malleability can be achieved for very rich classes of modifications. We construct an efficient code that is non-malleable with respect to modifications that affect each bit of the codeword arbitrarily (i.e., leave it untouched, flip it, or set it to either 0 or 1), but independently of the value of the other bits of the codeword. Using the probabilistic method, we also show a very strong and general statement: there exists a non-malleable code for every “small enough” family F of functions via which codewords can be modified. Although this probabilistic method argument does not directly yield efficient constructions, it gives us efficient non-malleable codes in the random-oracle model for very general classes of tampering functions—e.g., functions where every bit in the tampered codeword can depend arbitrarily on any 99% of the bits in the original codeword. As an application of non-malleable codes, we show that they provide an elegant algorithmic solution to the task of protecting functionalities implemented in hardware (e.g., signature cards) against “tampering attacks.” In such attacks, the secret state of a physical system is tampered, in the hopes that future interaction with the modified system will reveal some secret information. This problem was previously studied in the work of Gennaro et al. in 2004 under the name “algorithmic tamper proof security” (ATP). We show that non-malleable codes can be used to achieve important improvements over the prior work. In particular, we show that any functionality can be made secure against a large class of tampering attacks, simply by encoding the secret state with a non-malleable code while it is stored in memory. AU - Dziembowski, Stefan AU - Pietrzak, Krzysztof Z AU - Wichs, Daniel ID - 107 IS - 4 JF - Journal of the ACM TI - Non-malleable codes VL - 65 ER - TY - JOUR AB - In epithelial tissues, cells tightly connect to each other through cell–cell junctions, but they also present the remarkable capacity of reorganizing themselves without compromising tissue integrity. Upon injury, simple epithelia efficiently resolve small lesions through the action of actin cytoskeleton contractile structures at the wound edge and cellular rearrangements. However, the underlying mechanisms and how they cooperate are still poorly understood. In this study, we combine live imaging and theoretical modeling to reveal a novel and indispensable role for occluding junctions (OJs) in this process. We demonstrate that OJ loss of function leads to defects in wound-closure dynamics: instead of contracting, wounds dramatically increase their area. OJ mutants exhibit phenotypes in cell shape, cellular rearrangements, and mechanical properties as well as in actin cytoskeleton dynamics at the wound edge. We propose that OJs are essential for wound closure by impacting on epithelial mechanics at the tissue level, which in turn is crucial for correct regulation of the cellular events occurring at the wound edge. AU - Carvalho, Lara AU - Patricio, Pedro AU - Ponte, Susana AU - Heisenberg, Carl-Philipp J AU - Almeida, Luis AU - Nunes, André S. AU - Araújo, Nuno A.M. AU - Jacinto, Antonio ID - 5676 IS - 12 JF - Journal of Cell Biology SN - 00219525 TI - Occluding junctions as novel regulators of tissue mechanics during wound repair VL - 217 ER - TY - CONF AB - Clustering is a cornerstone of unsupervised learning which can be thought as disentangling multiple generative mechanisms underlying the data. In this paper we introduce an algorithmic framework to train mixtures of implicit generative models which we particularize for variational autoencoders. Relying on an additional set of discriminators, we propose a competitive procedure in which the models only need to approximate the portion of the data distribution from which they can produce realistic samples. As a byproduct, each model is simpler to train, and a clustering interpretation arises naturally from the partitioning of the training points among the models. We empirically show that our approach splits the training distribution in a reasonable way and increases the quality of the generated samples. AU - Locatello, Francesco AU - Vincent, Damien AU - Tolstikhin, Ilya AU - Ratsch, Gunnar AU - Gelly, Sylvain AU - Scholkopf, Bernhard ID - 14224 T2 - 6th International Conference on Learning Representations TI - Clustering meets implicit generative models ER - TY - GEN AB - Table S1. Genes with highest betweenness. Table S2. Local and Master regulators up-regulated. Table S3. Local and Master regulators down-regulated (XLSX 23 kb). AU - Higareda Almaraz, Juan AU - Karbiener, Michael AU - Giroud, Maude AU - Pauler, Florian AU - Gerhalter, Teresa AU - Herzig, Stephan AU - Scheideler, Marcel ID - 9807 TI - Additional file 1: Of Norepinephrine triggers an immediate-early regulatory network response in primary human white adipocytes ER - TY - GEN AB - Table S4. Counts per Gene per Million Reads Mapped. (XLSX 2751 kb). AU - Higareda Almaraz, Juan AU - Karbiener, Michael AU - Giroud, Maude AU - Pauler, Florian AU - Gerhalter, Teresa AU - Herzig, Stephan AU - Scheideler, Marcel ID - 9808 TI - Additional file 3: Of Norepinephrine triggers an immediate-early regulatory network response in primary human white adipocytes ER - TY - CONF AB - We show attacks on five data-independent memory-hard functions (iMHF) that were submitted to the password hashing competition (PHC). Informally, an MHF is a function which cannot be evaluated on dedicated hardware, like ASICs, at significantly lower hardware and/or energy cost than evaluating a single instance on a standard single-core architecture. Data-independent means the memory access pattern of the function is independent of the input; this makes iMHFs harder to construct than data-dependent ones, but the latter can be attacked by various side-channel attacks. Following [Alwen-Blocki'16], we capture the evaluation of an iMHF as a directed acyclic graph (DAG). The cumulative parallel pebbling complexity of this DAG is a measure for the hardware cost of evaluating the iMHF on an ASIC. Ideally, one would like the complexity of a DAG underlying an iMHF to be as close to quadratic in the number of nodes of the graph as possible. Instead, we show that (the DAGs underlying) the following iMHFs are far from this bound: Rig.v2, TwoCats and Gambit each having an exponent no more than 1.75. Moreover, we show that the complexity of the iMHF modes of the PHC finalists Pomelo and Lyra2 have exponents at most 1.83 and 1.67 respectively. To show this we investigate a combinatorial property of each underlying DAG (called its depth-robustness. By establishing upper bounds on this property we are then able to apply the general technique of [Alwen-Block'16] for analyzing the hardware costs of an iMHF. AU - Alwen, Joel F AU - Gazi, Peter AU - Kamath Hosdurg, Chethan AU - Klein, Karen AU - Osang, Georg F AU - Pietrzak, Krzysztof Z AU - Reyzin, Lenoid AU - Rolinek, Michal AU - Rybar, Michal ID - 193 T2 - Proceedings of the 2018 on Asia Conference on Computer and Communication Security TI - On the memory hardness of data independent password hashing functions ER - TY - CONF AB - We introduce a formal quantitative notion of “bit security” for a general type of cryptographic games (capturing both decision and search problems), aimed at capturing the intuition that a cryptographic primitive with k-bit security is as hard to break as an ideal cryptographic function requiring a brute force attack on a k-bit key space. Our new definition matches the notion of bit security commonly used by cryptographers and cryptanalysts when studying search (e.g., key recovery) problems, where the use of the traditional definition is well established. However, it produces a quantitatively different metric in the case of decision (indistinguishability) problems, where the use of (a straightforward generalization of) the traditional definition is more problematic and leads to a number of paradoxical situations or mismatches between theoretical/provable security and practical/common sense intuition. Key to our new definition is to consider adversaries that may explicitly declare failure of the attack. We support and justify the new definition by proving a number of technical results, including tight reductions between several standard cryptographic problems, a new hybrid theorem that preserves bit security, and an application to the security analysis of indistinguishability primitives making use of (approximate) floating point numbers. This is the first result showing that (standard precision) 53-bit floating point numbers can be used to achieve 100-bit security in the context of cryptographic primitives with general indistinguishability-based security definitions. Previous results of this type applied only to search problems, or special types of decision problems. AU - Micciancio, Daniele AU - Walter, Michael ID - 300 TI - On the bit security of cryptographic primitives VL - 10820 ER - TY - JOUR AB - Motivated by biological questions, we study configurations of equal spheres that neither pack nor cover. Placing their centers on a lattice, we define the soft density of the configuration by penalizing multiple overlaps. Considering the 1-parameter family of diagonally distorted 3-dimensional integer lattices, we show that the soft density is maximized at the FCC lattice. AU - Edelsbrunner, Herbert AU - Iglesias Ham, Mabel ID - 312 IS - 1 JF - SIAM J Discrete Math SN - 08954801 TI - On the optimality of the FCC lattice for soft sphere packing VL - 32 ER - TY - JOUR AB - We give a simple proof of T. Stehling's result [4], whereby in any normal tiling of the plane with convex polygons with number of sides not less than six, all tiles except a finite number are hexagons. AU - Akopyan, Arseniy ID - 409 IS - 4 JF - Comptes Rendus Mathematique SN - 1631073X TI - On the number of non-hexagons in a planar tiling VL - 356 ER - TY - JOUR AB - Reciprocity is a major factor in human social life and accounts for a large part of cooperation in our communities. Direct reciprocity arises when repeated interactions occur between the same individuals. The framework of iterated games formalizes this phenomenon. Despite being introduced more than five decades ago, the concept keeps offering beautiful surprises. Recent theoretical research driven by new mathematical tools has proposed a remarkable dichotomy among the crucial strategies: successful individuals either act as partners or as rivals. Rivals strive for unilateral advantages by applying selfish or extortionate strategies. Partners aim to share the payoff for mutual cooperation, but are ready to fight back when being exploited. Which of these behaviours evolves depends on the environment. Whereas small population sizes and a limited number of rounds favour rivalry, partner strategies are selected when populations are large and relationships stable. Only partners allow for evolution of cooperation, while the rivals’ attempt to put themselves first leads to defection. Hilbe et al. synthesize recent theoretical work on zero-determinant and ‘rival’ versus ‘partner’ strategies in social dilemmas. They describe the environments under which these contrasting selfish or cooperative strategies emerge in evolution. AU - Hilbe, Christian AU - Chatterjee, Krishnendu AU - Nowak, Martin ID - 419 JF - Nature Human Behaviour TI - Partners and rivals in direct reciprocity VL - 2 ER -