Page 77 - ISCI’2017
P. 77
Chapter 3
KEY SCHEDULE OF BLOCK SYMMETRIC CIPHERS
Alexandr A. Kuznetsov
Department of Information Systems and Technologies Security, V.N. Karazin Kharkiv National
University, Svobody sq., 4, Kharkov, 61022, Ukraine;
kuznetsov@karazin.ua
Yuriy I. Gorbenko
Department of Information Systems and Technologies Security, V.N. Karazin Kharkiv National
University, Svobody sq., 4, Kharkov, 61022, Ukraine;
gorbenkou@iit.kharkov.ua
Ievgeniia P. Kolovanova
Department of Information Systems and Technologies Security, V.N. Karazin Kharkiv National
University, Svobody sq., 4, Kharkov, 61022, Ukraine;
e.kolovanova@gmail.com
Abstract
We investigate combinatorial properties of the block symmetric ciphers key schedule in the assumption that the cyclic
(round) keys are generated randomly, with equal probability and independently of each other. The model of random
homogeneous substitution is used for an abstract description of this formation. Analytical expressions allow us to estimate
the power of implemented encryption-decryption maps set, obtain estimates of the probability properties of round keys
sequences and ratios of the average number of different key sequences to power of different master keys set. The
simulation results confirm the accuracy and validity of these analytical expressions.
Key words: key schedule, cyclic keys, combinatorial properties, block symmetric ciphers.
77
