<s>
In	O
cryptography	O
,	O
M8	B-Algorithm
is	O
a	O
block	O
cipher	O
designed	O
by	O
Hitachi	O
in	O
1999	O
.	O
</s>
<s>
It	O
is	O
a	O
modification	O
of	O
Hitachi	O
's	O
earlier	O
M6	B-Algorithm
algorithm	O
,	O
designed	O
for	O
greater	O
security	O
and	O
high	O
performance	O
in	O
both	O
hardware	O
and	O
32-bit	O
software	O
implementations	O
.	O
</s>
<s>
M8	B-Algorithm
was	O
registered	O
by	O
Hitachi	O
in	O
March	O
1999	O
as	O
ISO/IEC	O
9979-0020	O
.	O
</s>
<s>
Like	O
M6	B-Algorithm
,	O
M8	B-Algorithm
is	O
a	O
Feistel	B-Algorithm
cipher	I-Algorithm
with	O
a	O
block	O
size	O
of	O
64	O
bits	O
.	O
</s>
<s>
The	O
round	O
function	O
can	O
include	O
32-bit	O
rotations	O
,	O
XORs	B-Application
,	O
and	O
modular	O
addition	O
,	O
making	O
it	O
an	O
early	O
example	O
of	O
an	O
ARX	O
cipher	O
.	O
</s>
<s>
Making	O
the	O
rounds	O
key-dependent	O
is	O
intended	O
to	O
make	O
cryptanalysis	O
more	O
difficult	O
(	O
see	O
FROG	B-Algorithm
for	O
a	O
similar	O
design	O
philosophy	O
)	O
.	O
</s>
<s>
The	O
cipher	O
has	O
a	O
typical	O
Feistel	B-Algorithm
cipher	I-Algorithm
design	O
.	O
</s>
<s>
where	O
op1	O
to	O
op9	O
are	O
each	O
one	O
bit	O
(	O
0	O
=	O
addition	O
mod	O
232	O
,	O
1	O
=	O
XOR	B-Application
)	O
and	O
S1	O
to	O
S3	O
are	O
five	O
bits	O
each	O
.	O
</s>
<s>
The	O
following	O
is	O
an	O
implementation	O
of	O
the	O
cipher	O
in	O
Python	B-Language
.	O
</s>
