<s>
In	O
cryptography	O
,	O
Zodiac	B-Algorithm
is	O
a	O
block	O
cipher	O
designed	O
in	O
2000	O
by	O
Chang-Hyi	O
Lee	O
for	O
the	O
Korean	O
firm	O
SoftForum	O
.	O
</s>
<s>
Zodiac	B-Algorithm
uses	O
a	O
16-round	O
Feistel	B-Algorithm
network	I-Algorithm
structure	O
with	O
key	B-Algorithm
whitening	I-Algorithm
.	O
</s>
<s>
The	O
round	O
function	O
uses	O
only	O
XORs	B-Application
and	O
S-box	B-Algorithm
lookups	O
.	O
</s>
<s>
There	O
are	O
two	O
8×	O
8-bit	O
S-boxes	B-Algorithm
:	O
one	O
based	O
on	O
the	O
discrete	O
exponentiation	O
45x	O
as	O
in	O
SAFER	B-Algorithm
,	O
the	O
other	O
using	O
the	O
multiplicative	O
inverse	O
in	O
the	O
finite	O
field	O
GF(28 )	O
,	O
as	O
introduced	O
by	O
SHARK	B-Algorithm
.	O
</s>
<s>
Zodiac	B-Algorithm
is	O
theoretically	O
vulnerable	O
to	O
impossible	O
differential	O
cryptanalysis	O
,	O
which	O
can	O
recover	O
a	O
128-bit	O
key	O
in	O
2119	O
encryptions	O
.	O
</s>
