<s>
The	O
Scream	B-Algorithm
cipher	O
is	O
a	O
word-based	O
stream	B-Algorithm
cipher	I-Algorithm
developed	O
by	O
Shai	O
Halevi	O
,	O
Don	O
Coppersmith	O
and	O
Charanjit	O
Jutla	O
from	O
IBM	O
.	O
</s>
<s>
The	O
cipher	O
is	O
designed	O
as	O
a	O
software	O
efficient	O
stream	B-Algorithm
cipher	I-Algorithm
.	O
</s>
<s>
The	O
authors	O
describe	O
the	O
goal	O
of	O
the	O
cipher	O
to	O
be	O
a	O
more	O
secure	O
version	O
of	O
the	O
SEAL	B-Algorithm
cipher	O
.	O
</s>
<s>
The	O
general	O
design	O
of	O
Scream	B-Algorithm
is	O
close	O
to	O
the	O
design	O
of	O
SEAL	B-Algorithm
with	O
block	O
cipher-like	O
round	O
functions	O
.	O
</s>
<s>
There	O
are	O
two	O
versions	O
of	O
Scream	B-Algorithm
.	O
</s>
<s>
One	O
of	O
them	O
,	O
Scream-F	O
,	O
reuses	O
the	O
S-boxes	B-Algorithm
from	O
the	O
Advanced	B-Algorithm
Encryption	I-Algorithm
Standard	I-Algorithm
(	O
AES	B-Algorithm
)	O
block	O
cipher	O
,	O
while	O
the	O
other	O
,	O
Scream	B-Algorithm
,	O
internally	O
generates	O
new	O
,	O
key-dependent	O
S-boxes	B-Algorithm
as	O
part	O
of	O
the	O
initialization	O
phase	O
.	O
</s>
<s>
The	O
round	O
function	O
is	O
also	O
based	O
on	O
the	O
AES-round	O
function	O
,	O
but	O
is	O
narrower	O
,	O
64	O
bits	O
instead	O
of	O
128	O
bits	O
.	O
</s>
