Andreas Klein

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In this article we present some weaknesses in the RC4 cipher and their cryptographic applications. Especially we improve the attack described in [2] in such a way, that it will work, if the weak keys described in that paper are avoided. A further attack will work even if the first 256 Byte of the output remain unused. Finally we show that variants of the(More)
The development of statistically efficient and computationally practicable estimation methods for the analysis of structural equation models with multiple nonlinear effects has been called for by substantive researchers in psychology, marketing research, and sociology. But the development of efficient methods is complicated by the fact that a nonlinear(More)
We present improved lower bounds on the sizes of small maximal partial ovoids in the classical hermitian polar spaces, and improved upper bounds on the sizes of large maximal partial spreads in the classical hermitian polar spaces. Of particular importance is the presented upper bound on the size of a maximal partial spread of H(3,q2). For q = 2, 3, the(More)
Abstract. Visual cryptography schemes have been introduced in 1994 by Naor and Shamir. Their idea was to encode a secret image into n shadow images and to give exactly one such shadow image to each member of a group P of n persons. Whereas most work in recent years has been done concerning the problem of qualified and forbidden subsets of P or the question(More)
We start by defining generalised dual arcs, the motivation for defining them comes from cryptography, since they can serve as a tool to construct authentication codes and secret sharing schemes. We extend the characterisation of the tangent planes of the Veronesean surface V 4 2 in PG(5, q), q odd, described in [4], as a set of q + q + 1 planes in PG(5, q),(More)
Evaluating model fit in nonlinear multilevel structural equation models (MSEM) presents a challenge as no adequate test statistic is available. Nevertheless, using a product indicator approach a likelihood ratio test for linear models is provided which may also be useful for nonlinear MSEM. The main problem with nonlinear models is that product variables(More)
A variety of bacteriophages specific for different hosts, including Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Shigella dysenteriae, Staphylococcus aureus, and Vibrio comma, were frozen at a controlled rate to liquid nitrogen temperatures, and then quick-thawed. Glycerol (10%) was used as a protective additive.(More)
One-way cellular automata with restricted nondeterminism are investigated. The number of allowed nondeterministic state transitions is limited to a constant. It is shown that a limit to exactly one step does not decrease the language accepting capabilities. We prove a speed-up result that allows any linear-time computation to be sped-up to real-time. Some(More)