Short answers, pulled from the story.
SHARK is a block cipher in cryptography, identified as one of the direct predecessors of Rijndael, which became the Advanced Encryption Standard. It uses a 64-bit block size and a 128-bit key, and its design influenced the construction of the cipher that now secures much of the world's encrypted communications.
SHARK uses a 64-bit block size and a 128-bit key size. It processes data through six rounds in a structure known as an SP-network.
SHARK is named as one of the predecessors of Rijndael, the algorithm selected as the Advanced Encryption Standard. Structural elements of SHARK, including its use of algebraic S-boxes based on finite field inversion, carried forward into Rijndael's design.
Jakobsen and Knudsen showed in 1997 that five rounds of a modified version of SHARK could be broken using an interpolation attack. This attack exploits the algebraic structure of the cipher by treating the encryption function as a polynomial solvable with enough input-output pairs.
SHARK uses eight 8x8-bit S-boxes in its nonlinear transformation layer. Each is based on the function F(x) = x to the negative one, computed over the finite field GF(2 to the 8th power).
SHARK's linear transformation layer uses an MDS matrix representing a Reed-Solomon error correcting code. This choice guarantees strong diffusion, ensuring that a change in any single input bit propagates widely across the output.