Multiple-Differential Side-Channel Collision Attacks on AES

In this paper, two efficient multiple-differential methods to detect collisions in the presence of strong noise are proposed - binary and ternary voting. After collisions have been detected, the cryptographic key can be recovered from these collisions using such recent cryptanalytic techniques as linear [1] and algebraic [2] collision attacks. We refer to this combination of the collision detection methods and cryptanalytic techniques as multiple-differential collision attacks (MDCA). When applied to AES, MDCA using binary voting without profiling requires about 2.7 to 13.2 times less traces than the Hamming-weight based CPA for the same implementation. MDCA on AES using ternary voting with profiling and linear key recovery clearly outperforms CPA by requiring only about 6 online measurements for the range of noise amplitudes where CPA requires from 163 to 6912 measurements. These attacks do not need the S-box to be known. Moreover, neither key nor plaintexts have to be known to the attacker in the profiling stage.