SHARK

SHARK
General
DesignersVincent Rijmen, Joan Daemen, Bart Preneel, Antoon Bosselaers, Erik De Win
First published1996
SuccessorsKHAZAD, Rijndael
Cipher detail
Key sizes128 bits
Block sizes64 bits
StructureSubstitution–permutation network
Rounds6

In cryptography, SHARK is a block cipher identified as one of the predecessors of Rijndael (the Advanced Encryption Standard).

SHARK has a 64-bit block size and a 128-bit key size. It is a six-round SP-network which alternates a key mixing stage with linear and non-linear transformation layers. The linear transformation uses an MDS matrix representing a Reed–Solomon error correcting code in order to guarantee good diffusion. The nonlinear layer is composed of eight 8×8-bit S-boxes based on the function F(x) = x−1 over GF(28).

Five rounds of a modified version of SHARK can be broken using an interpolation attack (Jakobsen and Knudsen, 1997).