Paper 2015/1201

A Star-based Independent Biclique Attack on Full Rounds SQUARE

Zheng Yuan, Zhen Peng, and Ming Mao

Abstract

SQUARE is an iterated block cipher proposed by Daemen et.al. in FSE1997. Inspired by Bogdanov et.al.’s recent works [12], we first present an improved biclique attack, i.e. stat-based independent biclique attack on full rounds SQUARE in this paper. We construct a one round stat-based independent biclique for the initial round, and utilize matching with precomputation techniques to recover the whole key from the remaining rounds. The computing complexity of our attack is about $2^{(}126.17)$ encryptions and required data can be reduced to a single plaintext-ciphertext pair. To be the best of our knowledge, our attack has an optimal computing complexity and data complexity of biclique attack on full rounds SQUARE.