Some observations on the lightweight block cipher piccolo-80

Abstract

Piccolo is a 64-bit lightweight block cipher proposed by SONY corporation to be used in the constrained environments such as wireless sensor net work environments. In this paper, by algebraic analysis, we give some observations on Piccolo, including the linear analysis of the F-function, and a weakness of key scheduling. We found that the F-function could be matched with linear permutation with high probability. We revealed the statistical character of the Ffunction, which gives the attackers chance to distinguish piccolo from random permutation. We attack two rounds Piccolo-80 with the computational complexity 217 two rounds Piccolo-80 encryptions. We found that the subkeys in last two rounds of Piccolo-80 do not play the roles of hide information of internal states well, 16 bits of cipher text can be represented by the state of last but one round.