Truncated and higher order differentials. (English) Zbl 0939.94556

Knudsen, Lars R.

Preneel, Bart (ed.), Fast software encryption. 2nd international workshop, Leuven, Belgium, December 14-16, 1994. Proceedings. Berlin: Springer-Verlag. Lect. Notes Comput. Sci. 1008, 196-211 (1995).

Summary: Recently, X. Lai considered higher-order derivatives of discrete functions and introduced the concept of higher-order differentials. We introduce the concept of truncated differentials and present attacks on ciphers presumably secure against differential attacks, but vulnerable to attacks using higher-order and truncated differentials. Also we give a differential attack using truncated differentials on DES reduced to 6 rounds using only 46 chosen plaintexts with an expected running time of about the time of 3,500 encryptions. Finally it is shown how to find a minimum nonlinear order of a block cipher using higher-order differentials.
For the entire collection see [Zbl 0829.68005].

MSC:

94A60

Cryptography

Keywords:

higher-order derivatives of discrete functions; higher-order differentials; truncated differentials; differential attack; minimum nonlinear order; block cipher