<s>
In	O
cryptography	O
,	O
a	O
permutation	B-Algorithm
box	I-Algorithm
(	O
or	O
P-box	O
)	O
is	O
a	O
method	O
of	O
bit-shuffling	O
used	O
to	O
permute	B-Algorithm
or	O
transpose	B-Algorithm
bits	O
across	O
S-boxes	B-Algorithm
inputs	O
,	O
retaining	O
diffusion	O
while	O
transposing	B-Algorithm
.	O
</s>
<s>
In	O
block	O
ciphers	O
,	O
the	O
S-boxes	B-Algorithm
and	O
P-boxes	O
are	O
used	O
to	O
make	O
the	O
relation	O
between	O
the	O
plaintext	O
and	O
the	O
ciphertext	O
difficult	O
to	O
understand	O
(	O
see	O
Shannon	O
's	O
property	O
of	O
confusion	O
)	O
.	O
</s>
