Patrick Felke

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Recently a new class of collision attacks which was originally suggested by Hans Dobbertin has been introduced. These attacks use side channel analysis to detect internal collisions and are generally not restricted to a particular cryptographic algorithm. As an example, a collision attack against DES was proposed which combines internal collisions with side(More)
A Boolean function with an even number n = 2k of variables is called bent if it is maximally nonlinear. We present here a new construction of bent functions. Boolean functions of the form f(x) = tr(α1x1 + α2x2), α1, α2, x ∈ F2n , are considered, where the exponents di (i = 1, 2) are of Niho type, i.e. the restriction of xi on F2k is linear. We prove for d1(More)
Suppose that n=2k is even. We study the cross-correlation function between two m-sequences for Niho type decimations d=(2/sup k/-1)s+1. We develop a new technique to study the value distribution of these cross-correlation functions, which makes use of Dickson polynomials. As a first application, we derive here the distribution of the six-valued(More)
Quartz is a signature scheme based on an HFEvtrapdoor function published at Eurocrypt 1996. In this paper we study ”inversion” attacks for Quartz, i.e. attacks that solve the system of multivariate equations used in Quartz. We do not cover some special attacks that forge signatures without inversion. We are interested in methods to invert the HFEvtrapdoor(More)
We exhibit an infinite class of almost perfect nonlinear quadratic polynomials from F<sub>2n</sub> to F<sub>2n</sub> (n ges 12, n divisible by 3 but not by 9). We prove that these functions are EA-inequivalent to any power function and that they are CCZ-inequivalent to any Gold function. In a forthcoming full paper, we shall also prove that at least some of(More)
This documents states the research agenda for the future of cryptology. We show which areas deserve more research bridging the gap between applications and research. For more detailed problems see the STORK document “D6 – Open Problems in Cryptology”.
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