SHARK: Meaning (information, definition, explanation, facts)

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 SPN network which alternates a key mixing stage with linear and non-linear transformation layers. The linear transformation is derived from an error correcting code (a Reed-Solomon code) in order to guarantee good diffusion. The nonlinear layer is composed of eight 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 a interpolation attack (Jakobsen and Knudsen, 1997).

References

• Joan Daemen, Vincent Rijmen: The Design of Rijndael: AES - The Advanced Encryption Standard. Springer 2002, ISBN 3540425802.
• Thomas Jakobsen, Lars R. Knudsen: The Interpolation Attack on Block Ciphers. Fast Software Encryption 1997: 28–40
• Vincent Rijmen, Joan Daemen, Bart Preneel, Anton Bossalaers, Erik De Win: The Cipher SHARK. Fast Software Encryption 1996: 99–111