## Cryptology ePrint Archive: Report 2004/337

Security on Generalized Feistel Scheme with SP Round Function

Wu Wenling and Zhang Wentao and Lin Dongdai

Abstract: This paper studies the security against differential/linear cryptanalysis and the pseudorandomness for a class of generalized Feistel scheme with SP round function called $GFSP$. We consider the minimum number of active s-boxes in some consecutive rounds of $GFSP$,i.e., in four, eight and sixteen consecutive rounds, which provide the upper bound of the maximum differential/linear probabilities of 16-round $GFSP$ scheme, in order to evaluate the strength against differential/linear cryptanalysis. Furthermore, We investigate the pseudorandomness of $GFSP$, point out 7-round $GFSP$ is not pseudorandom for non-adaptive adversary, by using some distinguishers, and prove that 8-round $GFSP$ is pseudorandom for any adversaries.

Category / Keywords: secret-key cryptography / block cipher