Differential entropy analysis of the IDEA block cipher

This paper describes a new cryptanalytic technique that combines differential cryptanalysis with Shannon entropy. We call it differential entropy (DE). The objective is to exploit the non-uniform distribution of output differences from a given mapping as a distinguishing tool in cryptanalysis. Our preferred target is the IDEA block cipher, since we detected significantly low entropy at the output of its multiplication operation. We looked to further extend this entropy analysis to larger components and for a number of rounds. We present key-recovery attacks on up to 2.5-round IDEA in the single-key model and without weak-key assumptions. © 2013 Elsevier B.V. All rights reserved

A Salad of Block Ciphers

This book is a survey on the state of the art in block cipher design and analysis. It is work in progress, and it has been for the good part of the last three years -- sadly, for various reasons no significant change has been made during the last twelve months. However, it is also in a self-contained, useable, and relatively polished state, and for this reason I have decided to release this \textit{snapshot} onto the public as a service to the cryptographic community, both in order to obtain feedback, and also as a means to give something back to the community from which I have learned much. At some point I will produce a final version -- whatever being a ``final version\u27\u27 means in the constantly evolving field of block cipher design -- and I will publish it. In the meantime I hope the material contained here will be useful to other people