International Association
for Cryptologic Research

In this paper we introduce the differential-meet-in-the-middle framework, a new cryptanalysis technique against symmetric primitives. The idea of this new cryptanalysis method consists in combining into one attack techniques from both meet-in-the-middle and differential cryptanalysis. The introduced technique can be seen as a way of extending meet-in-the-middle attacks and their variants but also as a new way to perform the key recovery part in differential attacks. We provide a simple tool to search, given a differential, for efficient applications of this new attack and apply our approach, in combination with some additional techniques, to SKINNY-128-384. Our attack on SKINNY-128-384 permits to break 25 out of the 56 rounds of this variant and improves by two rounds the previous best known attacks in the single key model.