Linear fault analysis of block ciphers

Abstract

Differential fault analysis (DFA) has already been applied to attack many block ciphers with the help of inducing some faults at the last few rounds of block ciphers. Currently, a general countermeasure against DFA is to protect the last few rounds of block ciphers by means of redundancy. In this paper, we present a new fault attack on block ciphers called linear fault analysis (LFA), in which linear characteristics for some consecutive rounds of a block cipher will be utilized instead of exploiting differential distributions of S-Boxes within the block cipher in DFA. Basically, the new approach can handle the case that faults are induced several rounds earlier compared to DFA, thus leading to a threat to the protected implementations (against DFA) of block ciphers. For the purpose of illustration, we mount an effective attack on SERPENT by adopting LFA and achieve a good cryptanalytic result on SERPENT. We hope that our work enriches the picture on the applicability of fault attacks to block ciphers and could be beneficial to the security evaluation of block ciphers. © 2012 Springer-Verlag.