International Association for Cryptologic Research (IACR)
Abstract
In this paper, we extend the applicability of differential meet-
in-the-middle attacks, proposed at Crypto 2023, to truncated differen-
tials, and in addition, we introduce three new ideas to improve this type
of attack: we show how to add longer structures than the original pa-
per, we show how to improve the key recovery steps by introducing some
probability in them, and we combine this type of attacks with the state-
test technique, that was introduced in the context of impossible differ-
ential attacks. Furthermore, we have developed a MILP-based tool to
automate the search for a truncated differential-MITM attack with op-
timized overall complexity, incorporating some of the proposed improve-
ments. Thanks to this, we can build the best known attacks on the cipher
CRAFT, reaching 23 rounds against 21 previously; we provide a new at-
tack on 23-round SKINNY-64-192, and we improve the best attacks on
SKINNY-128-384