<s>
In	O
cryptography	O
,	O
SHARK	B-Algorithm
is	O
a	O
block	O
cipher	O
identified	O
as	O
one	O
of	O
the	O
predecessors	O
of	O
Rijndael	B-Algorithm
(	O
the	O
Advanced	B-Algorithm
Encryption	I-Algorithm
Standard	I-Algorithm
)	O
.	O
</s>
<s>
SHARK	B-Algorithm
has	O
a	O
64-bit	O
block	O
size	O
and	O
a	O
128-bit	O
key	O
size	O
.	O
</s>
<s>
It	O
is	O
a	O
six-round	O
SP-network	B-Algorithm
which	O
alternates	O
a	O
key	O
mixing	O
stage	O
with	O
linear	O
and	O
non-linear	O
transformation	O
layers	O
.	O
</s>
<s>
The	O
linear	O
transformation	O
uses	O
an	O
MDS	B-General_Concept
matrix	I-General_Concept
representing	O
a	O
Reed	B-Error_Name
–	I-Error_Name
Solomon	I-Error_Name
error	B-Error_Name
correcting	I-Error_Name
code	I-Error_Name
in	O
order	O
to	O
guarantee	O
good	O
diffusion	O
.	O
</s>
<s>
The	O
nonlinear	O
layer	O
is	O
composed	O
of	O
eight	O
8×	O
8-bit	O
S-boxes	B-Algorithm
based	O
on	O
the	O
function	O
F(x )	O
=	O
x−1	O
over	O
GF(28 )	O
.	O
</s>
<s>
Five	O
rounds	O
of	O
a	O
modified	O
version	O
of	O
SHARK	B-Algorithm
can	O
be	O
broken	O
using	O
an	O
interpolation	O
attack	O
(	O
Jakobsen	O
and	O
Knudsen	O
,	O
1997	O
)	O
.	O
</s>
