| General | |
|---|---|
| Designers | Vincent Rijmen, Joan Daemen, Bart Preneel, Antoon Bosselaers, Erik De Win |
| First published | 1996 |
| Successors | KHAZAD, Rijndael |
| Cipher detail | |
| Key sizes | 128 bits |
| Block sizes | 64 bits |
| Structure | Substitution–permutation network |
| Rounds | 6 |
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).