A Differential Fault Attack Technique against SPN Structures, with Application to the AES and Khazad

Abstract

In this paper we describe a differential fault attack technique working against Substitution-Permutation Networks, and requiring very few faulty ciphertexts. The fault model used is realistic, as we consider random faults affecting bytes (faults affecting one only bit are much harder to induce). We implemented our attack on a PC for both the AES and Khazad. We are able to break the AES-128 with only 2 faulty ciphertexts, assuming the fault occurs between the antepenultimate and the penultimate MixColumn; this is better than the previous fault attacks against AES [6][10][11]. Under similar hypothesis, Khazad is breakable with 3 faulty ciphertexts.KeywordsAESBlock CiphersFault AttacksSide-channel Attacks