Abstract

. In this paper we present a new 128-bit block cipher called Square. The original design of Square concentrates on the resistance against differential and linear cryptanalysis. However, after the initial design a dedicated attack was mounted that forced us to augment the number of rounds. The goal of this paper is the publication of the resulting cipher for public scrutiny. A C implementation of Square is available that runs at 2.63 MByte/s on a 100 MHz Pentium. Our M68HC05 Smart Card implementation fits in 547 bytes and takes less than 2 msec. (4 MHz Clock). The high degree of parallellism allows hardware implementations in the Gbit/s range today. 1 Introduction In this paper, we propose the block cipher Square. It has a block length and key length of 128 bits. However, its modular design approach allows extensions to higher block lengths in a straightforward way. The cipher has a new self-reciprocal structure, similar to that of Threeway and SHARK [2, 15]. The structure of the cip...

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