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Mathematical Methods of Cryptography
XS-circuits: hiding round oracles
S. V. Agievich Research Institute for Applied Problems of Mathematics and Informatics, Belarusian State University, Minsk
Abstract:
XS-circuits describe block ciphers that utilize 2 operations on binary words of fixed length: X — bitwise modulo 2 addition and S — substitution. In this paper, we develop a model of XS-circuits according to which several instances of a simple round circuit containing only one S operation are linked together and form a compound circuit called a cascade. S operations of a cascade are interpreted as independent round oracles. Determining some input/output pair of some round oracle from an input/output of the cascade is considered a security breach. We introduce the notion of hiding round oracles when such determining is hard. We show that a cascade based on a regular round circuit hides round oracles when the number of rounds is at least twice its dimension (the number of words in the processed data blocks).
Keywords:
block cipher, XS-circuit, round oracle, linear recurrence sequence.
Citation:
S. V. Agievich, “XS-circuits: hiding round oracles”, Prikl. Diskr. Mat. Suppl., 2021, no. 14, 59–61
Linking options:
https://www.mathnet.ru/eng/pdma532 https://www.mathnet.ru/eng/pdma/y2021/i14/p59
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