The science of brute force

We discuss recent advances in the science of brute-force. Very hard problems can now be solved by adding "brute reasoning" to the brute-force method, in the form of SAT solving (satisfiability solving). A key example is the recent solution of the boolean Pythagorean triples problem, which comes from the mathematical domain. The proof produced here, the largest proof ever constructed (200 TB), had a strong media echo, and scepticism about its "meaning" (or absence thereof) has been raised. We show, that these methods and extracted proofs have indeed meaning, and are indeed useful, when taking the real-world applications into account, the domain of safety and verification

Computer Science for Continuous Data:Survey, Vision, Theory, and Practice of a Computer Analysis System

Building on George Boole's work, Logic provides a rigorous foundation for the powerful tools in Computer Science that underlie nowadays ubiquitous processing of discrete data, such as strings or graphs. Concerning continuous data, already Alan Turing had applied "his" machines to formalize and study the processing of real numbers: an aspect of his oeuvre that we transform from theory to practice.The present essay surveys the state of the art and envisions the future of Computer Science for continuous data: natively, beyond brute-force discretization, based on and guided by and extending classical discrete Computer Science, as bridge between Pure and Applied Mathematics

Key Agreement Protocol (KAP) Based on Matrix Power Function

* Work is partially supported by the Lithuanian State Science and Studies Foundation.The key agreement protocol (KAP) is constructed using matrix power functions. These functions are based on matrix ring action on some matrix set. Matrix power functions have some indications as being a one- way function since they are linked with certain generalized satisfiability problems which are potentially NP- Complete. A working example of KAP with guaranteed brute force attack prevention is presented for certain algebraic structures. The main advantage of proposed KAP is considerable fast computations and avoidance of arithmetic operations with long integers

Face Identification by a Cascade of Rejection Classifiers

Nearest neighbor search is commonly employed in face recognition but it does not scale well to large dataset sizes. A strategy to combine rejection classifiers into a cascade for face identification is proposed in this paper. A rejection classifier for a pair of classes is defined to reject at least one of the classes with high confidence. These rejection classifiers are able to share discriminants in feature space and at the same time have high confidence in the rejection decision. In the face identification problem, it is possible that a pair of known individual faces are very dissimilar. It is very unlikely that both of them are close to an unknown face in the feature space. Hence, only one of them needs to be considered. Using a cascade structure of rejection classifiers, the scope of nearest neighbor search can be reduced significantly. Experiments on Face Recognition Grand Challenge (FRGC) version 1 data demonstrate that the proposed method achieves significant speed up and an accuracy comparable with the brute force Nearest Neighbor method. In addition, a graph cut based clustering technique is employed to demonstrate that the pairwise separability of these rejection classifiers is capable of semantic grouping.National Science Foundation (EIA-0202067, IIS-0329009); Office of Naval Research (N00014-03-1-0108

Effects of surface interactions on heterogeneous ice nucleation for a monatomic water model

Despite its importance in atmospheric science, much remains unknown about the microscopic mechanism of heterogeneous ice nucleation. In this work, we perform hybrid Monte Carlo simulations of the heterogeneous nucleation of ice on a range of generic surfaces, both flat and structured, in order to probe the underlying factors affecting the nucleation process. The structured surfaces we study comprise one basal plane bilayer of ice with varying lattice parameters and interaction strengths. We show that what determines the propensity for nucleation is not just the surface attraction, but also the orientational ordering imposed on liquid water near a surface. In particular, varying the ratio of the surface's attraction and orientational ordering can change the mechanism by which nucleation occurs: ice can nucleate on the structured surface even when the orientational ordering imposed by the surface is weak, as the water molecules that interact strongly with the surface are themselves a good template for further growth. We also show that lattice matching is important for heterogeneous nucleation on the structured surface we study. We rationalise these brute-force simulation results by explicitly calculating the interfacial free energies of ice and liquid water in contact with the nucleating surface and their variation with surface interaction parameters

Hill-climbing and brute-force attacks on biometric systems: A case study in match-on-card fingerprint verification

Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. M. Martínez-Díaz, J. Fiérrez-Aguilar, F. Alonso-Fernández, J. Ortega-García, J.A. Siguenza, "Hill-Climbing and Brute-Force Attacks on Biometric Systems: A Case Study in Match-on-Card Fingerprint Verification" in Proceedings of 40th Annual IEEE International Carnahan Conferences Security Technology ICCST, Lexington, KY (USA), 2006, 151 - 159In this paper, we study the robustness of state-of-the-art automatic fingerprint verification systems against hill climbing and brute-force attacks. We compare the performance of this type of attacks against two different minutiae-based systems, the NIST Fingerprint Image Software 2 (NFIS2) reference system and a Match-on-Card based system. In order to study their success rate, the attacks are analyzed and modified in each scenario. We focus on the influence of initial conditions in hill-climbing attacks, like the number of minutiae in the synthetically generated templates or the performance of each type of modification in the template. We demonstrate how slight modifications in the hill-climbing algorithm lead to very different success ratesThis work has been supported by the Spanish Ministry of Defense, BioSecure NoE and the TIC2003-08382-C05-01 project of the Spanish Ministry of Science and Technolog