<s>
In	O
cryptography	O
,	O
KN-Cipher	B-Algorithm
is	O
a	O
block	O
cipher	O
created	O
by	O
Kaisa	O
Nyberg	O
and	O
Lars	O
Knudsen	O
in	O
1995	O
.	O
</s>
<s>
One	O
of	O
the	O
first	O
ciphers	O
designed	O
to	O
be	O
provably	O
secure	O
against	O
ordinary	O
differential	O
cryptanalysis	O
,	O
KN-Cipher	B-Algorithm
was	O
later	O
broken	O
using	O
higher	O
order	O
differential	O
cryptanalysis	O
.	O
</s>
<s>
Presented	O
as	O
"	O
a	O
prototype	O
...	O
compatible	O
with	O
DES	B-Algorithm
"	O
,	O
the	O
algorithm	O
has	O
a	O
64-bit	O
block	O
size	O
and	O
a	O
6-round	O
Feistel	B-Algorithm
network	I-Algorithm
structure	O
.	O
</s>
<s>
The	O
designers	O
did	O
not	O
specify	O
any	O
key	B-Algorithm
schedule	I-Algorithm
for	O
the	O
cipher	O
;	O
they	O
state	O
,	O
"	O
All	O
round	B-Algorithm
keys	I-Algorithm
should	O
be	O
independent	O
,	O
therefore	O
we	O
need	O
at	O
least	O
198	O
key	O
bits.	O
"	O
</s>
<s>
Jakobsen	O
&	O
Knudsen	O
's	O
higher	O
order	O
differential	O
cryptanalysis	O
breaks	O
KN-Cipher	B-Algorithm
with	O
only	O
512	O
chosen	O
plaintexts	O
and	O
241	O
running	O
time	O
,	O
or	O
with	O
32	O
chosen	O
plaintexts	O
and	O
270	O
running	O
time	O
.	O
</s>
