Paper 2020/978

Linear and Partly-Pseudo-Linear Cryptanalysis of Reduced-Round SPARX Cipher

Sarah Alzakari and Poorvi Vora

Abstract

We propose a new cryptanalytic technique and key recovery attack for the Sparx cipher, Partly-Pseudo-Linear Cryptanalysis, a meet-in-the-middle attack combining linear and pseudo-linear approximations. We observe improvements over the linear hull attacks in the literature for Sparx 128/128 and 128/256. Additionally, we generate another attack for comparison purposes, using the Cho-Pieprzyk property for a fully-linear approximation and a corresponding key recovery attack. We observe improvements on the data complexity, bias, and number of recovered key bits, over all variants of Sparx, when compared to the use of only the Cho-Pieprzyk approximation.

Note: This paper is submitted to ATIS 2020 conference. (under review)