Abstract:
This paper is motivated by some results presented by
Knudsen, Robshaw and Wagner at Crypto'99, that
described many attacks of reduced versions of Skipjack,
some of them being erroneous.
Differential cryptanalysis is based on distinguishers,
any attack should prove that the events that
triggers the analysis has not the same probability
for the cipher than for a random function.
In particular, the composition of differential
for successive parts of a cipher should be done
very carefully to lead to an attack.