<s>
AES	B-Algorithm
uses	O
a	O
key	B-Algorithm
schedule	I-Algorithm
to	O
expand	O
a	O
short	O
key	O
into	O
a	O
number	O
of	O
separate	O
round	B-Algorithm
keys	I-Algorithm
.	O
</s>
<s>
The	O
three	O
AES	B-Algorithm
variants	O
have	O
a	O
different	O
number	O
of	O
rounds	O
.	O
</s>
<s>
Each	O
variant	O
requires	O
a	O
separate	O
128-bit	O
round	B-Algorithm
key	I-Algorithm
for	O
each	O
round	O
plus	O
one	O
more	O
.	O
</s>
<s>
The	O
key	B-Algorithm
schedule	I-Algorithm
produces	O
the	O
needed	O
round	B-Algorithm
keys	I-Algorithm
from	O
the	O
initial	O
key	O
.	O
</s>
<s>
AES	B-Algorithm
uses	O
up	O
to	O
for	O
AES-128	B-Algorithm
(	O
as	O
11	O
round	B-Algorithm
keys	I-Algorithm
are	O
needed	O
)	O
,	O
up	O
to	O
for	O
AES-192	B-Algorithm
,	O
and	O
up	O
to	O
for	O
AES-256	B-Algorithm
.	O
</s>
<s>
Also	O
define	O
as	O
a	O
one-byte	O
left	B-Algorithm
circular	I-Algorithm
shift	I-Algorithm
:	O
</s>
<s>
and	O
as	O
an	O
application	O
of	O
the	O
AES	B-Algorithm
S-box	O
to	O
each	O
of	O
the	O
four	O
bytes	O
of	O
the	O
word	O
:	O
</s>
