Differential fault analysis of HC-128

Abstract

HC-128 is a high speed stream cipher with a 128-bit secret key and a 128-bit initialization vector. It has passed all the three stages of the ECRYPT stream cipher project and is a member of the eSTREAM software portfolio. In this paper, we present a differential fault analysis attack on HC-128. The fault model in which we analyze the cipher is the one in which the attacker is able to fault a random word of the inner state of the cipher but cannot control its exact location nor its new faulted value. To perform the attack, we exploit the fact that some of the inner state words in HC-128 may be utilized several times without being updated. Our attack requires about 7968 faults and recovers the complete internal state of HC-128 by solving a set of 32 systems of linear equations over Z2 in 1024 variables. © 2010 Springer-Verlag.