Fast Software Encryption

Volume 2355 of the series Lecture Notes in Computer Science pp 328-335


Flaws in Differential Cryptanalysis of Skipjack

  • Louis GranboulanAffiliated withÉcole Normale Supérieure


This paper is motivated by some results presented by Knudsen, Robshaw and Wagner at Crypto’99 [3], 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.

This revised version of the paper includes the exact computations of some probabilities and repairs the attack of the first half of Skipjack.