ARXtools: A toolkit for ARX analysis

ARX designs are quite popular, but analysis of these schemes is hard because of their bit-level structure. This makes tasks such as building a differential characteristic very tedious. In this document, we present the result of our work in trying to help with analysis of ARX designs. We describe a toolkit to study ARX constructions, and present some preliminary results obtained with it. This is still a work in progress, but we wont to release the tools so that they can be used by anyone, and we hope this will will lead to new results. In this document, we give some explanation of how the tool works, and the full toolkit will be available for download. We did not manage to automate the search of differential paths, but our tools can help the cryptanalyst to build paths, and help uncover incompatibilities in published paths. Our main result so far show that differential characteristics used in some recent boomerang attacks are in fact incompatible, and those attacks will not work as expected.