Section: New Results

Using Constraint Programming to Solve a Cryptanalytic Problem

Participant : Marine Minier.

In [7], we describe Constraint Programming (CP) models to solve a cryptanalytic problem: the related key differential attack against the standard block cipher AES. We show that CP solvers are able to solve these problems quicker than dedicated cryptanalysis tools, and we prove that the 11 rounds solution on AES-192 claimed to be optimal is wrong. Instead, we provide the best related key differential characteristic on 10 rounds of AES-192. We also improved the related-key distinguisher and the basic related-key differential attack on the full AES-256 by a factor $2^6$ and the $q$-multicollisions by a factor 2.