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## Seminars given

**
***May 22, 2003* - Affine Equivalence Detection - A Useful Tool for the Analysis of
S-Boxes

by Christophe De Cannière

Abstract: | Substitution boxes (S-boxes) play an important role in many symmetric
encryption algorithms. In the last decade, much effort has been focused
on the analysis and the design of cryptographically strong S-boxes.
Criteria have been developed to estimate the resistance of S-boxes
against different types of attacks such as differential and linear
cryptanalysis. Currently, researchers are facing the problem of
evaluating the strength of S-boxes with respect to possible algebraic
attacks. Many interesting properties of S-boxes are invariant under
affine transformations and a natural way to simplify their analysis is
to study the equivalence classes defined by these transformations. In
this talk, we will present different efficient algorithms for detecting
linear and affine equivalence relations and we will show how they can
be used to classify S-boxes. |