Confidential algorithm for the approximate graph vertex covering problem is presented in this article. It can preserve privacy of data at every stage of the computation, which is very important in context of cloud computing. Security of our solution is based on fully homomorphic encryption scheme. The time complexity and the security aspects of considered algorithm are described.
The article is devoted to generation techniques of the new public key crypto-systems, which are based on application of indistinguishability obfuscation methods to selected private key crypto-systems. The techniques are applied to symmetric key crypto-system and the target system is asymmetric one. As an input for our approach an implementation of symmetric block cipher with a given private-key is considered. Different obfuscation methods are subjected to processing. The targetsystem would be treated as a public-key for newly created public crypto-system. The approach seems to be interesting from theoretical point of view. Moreover, it can be useful for information protection in a cloud-computing model.
This work presents the results of the research of the effect of the inoculant Emgesal Flux 5 on the microstructure of the magnesium alloy AZ91. The concentration of the inoculant was increased in samples in the range from 0.1% to 0.6%. The thermal processes were examined with the use of Derivative and Thermal Analysis (DTA). During the examination, the DTA samplers were preheated up to 180 °C. A particular attention was paid to finding the optimum amount of inoculant, which would cause fragmentation of the microstructure. The concentration of each element was verified by means of a spark spectrometer. In addition, the microstructures of the samples were examined with the use of an optical microscope, and an image analysis with a statistical analysis using the NIS–Elements program were carried out. Those analyses aimed at examining the differences between the grain diameters of phase αMg and eutectic αMg+γ(Mg17Al12) in the prepared samples as well as the average size of each type of grain by way of measuring their perimeters. This paper is an introduction to a further research of grain refinement in magnesium alloys, especially AZ91. Another purpose of this research is to achieve better microstructure fragmentation of magnesium alloys without the related changes of the chemical composition, which should improve the mechanical properties.