Borislav Stoyanov

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The need of software-flexible stream ciphers has led to several alternative proposals in the last few years. One of them is a new Pseudo Random Number Generator (PRNG), named N-adic Summation-Shrinking (NSumSG), which architecture is described in this paper. It uses N-1 parallel working slave summation generators and one N-adic summation generator,(More)
We present a novel image encryption algorithm using Chebyshev polynomial based on permutation and substitution and Duffing map based on substitution. Comprehensive security analysis has been performed on the designed scheme using key space analysis, visual testing, histogram analysis, information entropy calculation, correlation coefficient analysis,(More)
The article suggests a formal model of Distributed Database Management Systems (DDBMS) and an approach for Distributed Database Systems (DDB) modeling. It is suggested to use general purpose system simulation (GPSS) for simulation modeling. Queuing systems models modelling the execution of two-phase locking (2PL) in DDB with Data replication are suggested:(More)
This paper shows the potential of neural networks based on the Adaptive Resonance Theory as tools that generate warning signals when bankruptcy of a company is expected (bankruptcy prediction problem). Using that class of neural networks is still unexplored to date. We examined four of the most popular networks of the class – fuzzy, distributed, instance(More)
We present several useful applications of the CTI index in the context of various chemoinformatics tasks. Charge-related Topological Index (CTI) was introduced initially by Bangov for solving the problem of 2D structure isomorphism within the computer-assisted structure generation from a gross formula [1]. CTI is a real number defined as a sum over all atom(More)