TY - CPAPER AB - Constructing a block cipher requires us to define a random permutation, which is usually performed by the Feistel scheme and its variants. In this paper we investigate the Lai-Massey scheme which was used in IDEA. We show that we cannot use it “as is” in order to obtain results like the Luby-Rackoff theorem. This can however be done by introducing a simple function which has an orthomorphism property. We also show that this design offers nice decorrelation properties, and we propose a block cipher family called Walnut T1 - On the Lai-Massey scheme DA - 1999 AU - Vaudenay, Serge JF - International Conference on the Theory and Applications of Cryptology and Information Security, Advances in Cryptology - ASIACRYPT'99 SP - 8-19 VL - 1716 EP - 8-19 ID - 99403 UR - http://www.springer.com/ UR - http://infoscience.epfl.ch/record/99403/files/Vau99c.ps ER -