<s>
Rabbit	B-Algorithm
is	O
a	O
high-speed	O
stream	B-Algorithm
cipher	I-Algorithm
from	O
2003	O
.	O
</s>
<s>
The	O
algorithm	O
and	O
source	O
code	O
was	O
released	O
in	O
2008	O
as	O
public	B-Application
domain	I-Application
software	I-Application
.	O
</s>
<s>
Rabbit	B-Algorithm
was	O
first	O
presented	O
in	O
February	O
2003	O
at	O
the	O
10th	O
FSE	O
workshop	O
.	O
</s>
<s>
Rabbit	B-Algorithm
was	O
designed	O
by	O
Martin	O
Boesgaard	O
,	O
Mette	O
Vesterager	O
,	O
Thomas	O
Pedersen	O
,	O
Jesper	O
Christiansen	O
and	O
Ove	O
Scavenius	O
.	O
</s>
<s>
The	O
authors	O
of	O
the	O
cipher	O
have	O
provided	O
a	O
full	O
set	O
of	O
cryptanalytic	O
white	O
papers	O
on	O
the	O
Cryptico	B-Algorithm
home	O
page	O
.	O
</s>
<s>
Cryptico	B-Algorithm
had	O
patents	O
pending	O
for	O
the	O
algorithm	O
and	O
for	O
many	O
years	O
required	O
a	O
license	O
fee	O
for	O
commercial	O
use	O
of	O
the	O
cipher	O
which	O
was	O
waived	O
for	O
non-commercial	O
uses	O
.	O
</s>
<s>
Also	O
the	O
website	O
states	O
that	O
the	O
algorithm	O
and	O
implementation	O
is	O
public	B-Application
domain	I-Application
software	I-Application
and	O
offers	O
the	O
source	O
code	O
free	O
for	O
download	O
.	O
</s>
<s>
Rabbit	B-Algorithm
uses	O
a	O
128-bit	O
key	O
and	O
a	O
64-bit	O
initialization	O
vector	O
.	O
</s>
<s>
The	O
mixing	O
function	O
is	O
entirely	O
based	O
on	O
arithmetical	O
operations	O
that	O
are	O
available	O
on	O
a	O
modern	O
processor	O
,	O
i.e.	O
,	O
no	O
S-boxes	B-Algorithm
or	O
lookup	O
tables	O
are	O
required	O
to	O
implement	O
the	O
cipher	O
.	O
</s>
<s>
The	O
g-function	O
used	O
in	O
Rabbit	B-Algorithm
–	O
squaring	O
a	O
32-bit	O
number	O
to	O
produce	O
a	O
64-bit	O
number	O
,	O
and	O
then	O
combining	O
the	O
left	O
half	O
and	O
the	O
right	O
half	O
of	O
that	O
square	O
number	O
with	O
xor	O
,	O
to	O
produce	O
a	O
32-bit	O
result	O
–	O
provides	O
much	O
better	O
results	O
than	O
using	O
the	O
32	O
middle	O
bits	O
of	O
that	O
squared	O
number	O
(	O
the	O
middle-square	B-Algorithm
method	I-Algorithm
)	O
.	O
</s>
<s>
Rabbit	B-Algorithm
claims	O
128-bit	O
security	O
against	O
attackers	O
whose	O
target	O
is	O
one	O
specific	O
key	O
.	O
</s>
<s>
A	O
small	O
bias	O
in	O
the	O
output	O
of	O
Rabbit	B-Algorithm
exists	O
,	O
resulting	O
in	O
a	O
distinguisher	O
with	O
2247	O
complexity	O
discovered	O
by	O
Jean-Philippe	O
Aumasson	O
in	O
December	O
2006	O
.	O
</s>
<s>
Even	O
though	O
this	O
distinguisher	O
was	O
improved	O
to	O
2158	O
in	O
2008	O
,	O
it	O
is	O
not	O
a	O
threat	O
to	O
Rabbit	B-Algorithm
's	O
security	O
because	O
its	O
complexity	O
is	O
significantly	O
higher	O
than	O
the	O
brute-force	O
of	O
the	O
key	O
space	O
(	O
2128	O
)	O
.	O
</s>
