<s>
In	O
cryptography	O
,	O
BassOmatic	B-Algorithm
is	O
the	O
symmetric-key	B-Algorithm
cipher	I-Algorithm
designed	O
by	O
Phil	O
Zimmermann	O
as	O
part	O
of	O
his	O
email	O
encryption	O
software	O
PGP	B-Application
(	O
in	O
the	O
first	O
release	O
,	O
version	O
1.0	O
)	O
.	O
</s>
<s>
After	O
Eli	O
Biham	O
pointed	O
out	O
to	O
him	O
several	O
serious	O
weaknesses	O
in	O
the	O
BassOmatic	B-Algorithm
algorithm	O
over	O
lunch	O
at	O
the	O
1991	O
CRYPTO	O
conference	O
,	O
Zimmermann	O
replaced	O
it	O
with	O
IDEA	B-Algorithm
in	O
subsequent	O
versions	O
of	O
PGP	B-Application
.	O
</s>
<s>
The	O
name	O
is	O
explained	O
in	O
this	O
comment	O
from	O
the	O
source	O
code	O
:	O
"	O
BassOmatic	B-Algorithm
gets	O
its	O
name	O
from	O
an	O
old	O
Dan	O
Aykroyd	O
Saturday	O
Night	O
Live	O
skit	O
involving	O
a	O
blender	O
and	O
a	O
whole	O
fish	O
.	O
</s>
<s>
The	O
BassOmatic	B-Algorithm
algorithm	O
does	O
to	O
data	O
what	O
the	O
original	O
BassOmatic	B-Algorithm
did	O
to	O
the	O
fish.	O
"	O
</s>
<s>
Bit	O
4	O
selects	O
between	O
two	O
possible	O
key	B-Algorithm
schedules	I-Algorithm
:	O
one	O
using	O
the	O
key	O
to	O
seed	O
a	O
pseudorandom	B-Algorithm
number	I-Algorithm
generator	I-Algorithm
,	O
the	O
other	O
using	O
BassOmatic	B-Algorithm
itself	O
.	O
</s>
<s>
The	O
chosen	O
key	B-Algorithm
schedule	I-Algorithm
produces	O
a	O
total	O
of	O
8	O
permutation	B-Algorithm
tables	O
,	O
each	O
a	O
permutation	B-Algorithm
of	O
the	O
numbers	O
0	O
to	O
255	O
.	O
</s>
<s>
Each	O
round	O
consists	O
of	O
4	O
operations	O
:	O
XORing	O
the	O
block	O
with	O
one	O
of	O
the	O
permutation	B-Algorithm
tables	O
,	O
shredding	O
or	O
permuting	O
individual	O
bits	O
throughout	O
the	O
block	O
,	O
an	O
unkeyed	O
diffusion	O
called	O
raking	O
,	O
and	O
a	O
substitution	O
step	O
using	O
the	O
permutation	B-Algorithm
tables	O
as	O
S-boxes	B-Algorithm
.	O
</s>
<s>
The	O
permutation	B-Algorithm
tables	O
stay	O
the	O
same	O
through	O
all	O
rounds	O
of	O
encryption	O
on	O
a	O
given	O
block	O
,	O
but	O
if	O
control	O
bit	O
5	O
is	O
set	O
,	O
then	O
the	O
tables	O
are	O
regenerated	O
after	O
each	O
block	O
.	O
</s>
