Double SP-Functions: Enhanced Generalized Feistel Networks: Extended Abstract

Andrey Bogdanov, Kyoji Shibutani

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Abstract

This work deals with the security and efficiency of type-I and type-II generalized Feistel networks (GFNs) with 4 lines. We propose to instantiate the GFNs with double SP-functions (substitutionpermutation layer followed by another substitution-permutation layer) instead of single SP-functions (one substitution-permutation layer). We provide tight lower bounds on the number of differentially and linearly active functions and S-boxes in such ciphers. Based on these bounds, we show that the instantiation with double SP-functions using MDS diffusion has a proportion of differentially and linearly active S-boxes by up to 33% and 50% higher than that with single SP-functions for type-I and type-11 GENs, respectively. This opens up the possibility of designing more efficient block ciphers based on GFN structure. Note that type-1 and type-II GFNs are the only non-contracting OFNs with 4 lines under a reasonable definition of a GFN.
Original languageEnglish
Title of host publicationInformation Security and Privacy. Proceedings
PublisherSpringer
Publication date2011
Pages106-119
ISBN (Print)978-3-642-22496-6
ISBN (Electronic)978-3-642-22497-3
Publication statusPublished - 2011
Externally publishedYes
Event16th Australasian Conference on Information Security and Privacy - Melbourne, Australia
Duration: 11 Jul 201113 Jul 2011
Conference number: 16

Conference

Conference16th Australasian Conference on Information Security and Privacy
Number16
CountryAustralia
CityMelbourne
Period11/07/201113/07/2011
SeriesLecture Notes in Computer Science
Volume6812
ISSN0302-9743

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