Cryptanalysis of McGuffin

This paper shows that the actual proposal for an unbalanced Feistel network by Schneier and Blaze is as vulnerable to differential cryptanalysis as the DES. 1 McGuffin Schneier and Blaze introduce in [SB95] a new kind of block ciphers: the Generalized Unbalanced Feistel Network. Together with the general architecture they give a complete specification of an example. The basic idea is to split the input of each round into unequal parts. In the example, the 64-bit input is split into a 48-bit input of the F-function, and a 16-bit part that is exored with the output of the F-function. The F-function consists of the 8 S-boxes of the DES, but the two middle output bits of each S-box are neglected in order to obtain a 16-bit output. 2 Differential Characteristics In [Ma94] Matsui demonstrated that one can find the best differential characteristics and linear relations for the DES with a clever search algorithm. This encouraged us to try the same for McGuffin. For the DES it is very important...

• Type: Conference
• Year: 1994
• Where: FSE
• Authors: Vincent Rijmen, Bart Preneel
• Keywords: Cryptology, FSE 1994, McGuffin, McGuffin Schneier, Unbalanced Feistel Network