期刊名称：Eastern-European Journal of Enterprise Technologies
印刷版ISSN：1729-3774
电子版ISSN：1729-4061
出版年度：2018
卷号：4
期号：9
页码：14-19
DOI：10.15587/1729-4061.2018.139682
语种：English
出版社：PC Technology Center
摘要：The adaptation and application of the method for estimating the upper bound of the probability of two-round differentials for the block symmetric cipher Kalyna is carried out. This cipher was adopted as the Ukrainian standard DSTU 7624: 2014 in 2015. Known methods allow getting only the approximate value of this parameter for this cipher or cannot be applied explicitly through the structural features of this cipher. Using the approximate probability of two-round differentials gives an even greater error in the evaluation of the probabilities of differentials with a large number of rounds, as well as in assessing the resistance of the encryption algorithm to other types of differential attacks.The main stages of the used method are the following: definition of the minimum number of active S-boxes; definition of the type of differential characteristic having the maximum probability; determination of the number and probabilities of additional differential characteristics.In the course of research, an adapted method has allowed clarifying the upper bound of the probability of 2-round differentials for the cipher Kalyna significantly. This bound is ≈2–47.3 instead of 2–40 when using the method for nested SPN ciphers.The elaborated upper bound of the probability of 2-round differentials allowed clarifying also the bound value of the probability of 4-round differentials. For Kalyna-128 (block size 128 bits), the value is specified 214.6 times, for Kalyna-256 – 229.2 times, Kalyna-512 – 258.4 times.The main advantage of the method adapted for the Kalyna cipher was the possibility of a significant specification of the upper bound of the probability of a 2-round differential. The disadvantage of the adapted method is that assumptions are made, such as, for example, the use of one substitution instead of four in the original algorithm. The result of this assumption is that a real bound of the probability of 2-round differentials could be even smaller.
