<s>
In	O
cryptography	O
,	O
MISTY1	B-Algorithm
(	O
or	O
MISTY-1	B-Algorithm
)	O
is	O
a	O
block	O
cipher	O
designed	O
in	O
1995	O
by	O
Mitsuru	O
Matsui	O
and	O
others	O
for	O
Mitsubishi	O
Electric	O
.	O
</s>
<s>
MISTY1	B-Algorithm
is	O
one	O
of	O
the	O
selected	O
algorithms	O
in	O
the	O
European	O
NESSIE	O
project	O
,	O
and	O
has	O
been	O
among	O
the	O
cryptographic	O
techniques	O
recommended	O
for	O
Japanese	O
government	O
use	O
by	O
CRYPTREC	O
in	O
2003	O
;	O
however	O
,	O
it	O
was	O
dropped	O
to	O
"	O
candidate	O
"	O
by	O
CRYPTREC	O
revision	O
in	O
2013	O
.	O
</s>
<s>
However	O
,	O
it	O
was	O
successfully	O
broken	O
in	O
2015	O
by	O
Yosuke	O
Todo	O
using	O
integral	B-General_Concept
cryptanalysis	I-General_Concept
;	O
this	O
attack	O
was	O
improved	O
in	O
the	O
same	O
year	O
by	O
Achiya	O
Bar-On	O
.	O
</s>
<s>
"	O
MISTY	B-Algorithm
"	O
can	O
stand	O
for	O
"	O
Mitsubishi	O
Improved	O
Security	O
Technology	O
"	O
;	O
it	O
is	O
also	O
the	O
initials	O
of	O
the	O
researchers	O
involved	O
in	O
its	O
development	O
:	O
Matsui	O
Mitsuru	O
,	O
Ichikawa	O
Tetsuya	O
,	O
Sorimachi	O
Toru	O
,	O
Tokita	O
Toshio	O
,	O
and	O
Yamagishi	O
Atsuhiro	O
.	O
</s>
<s>
MISTY1	B-Algorithm
is	O
covered	O
by	O
patents	O
,	O
although	O
the	O
algorithm	O
is	O
freely	O
available	O
for	O
academic	O
(	O
non-profit	O
)	O
use	O
in	O
RFC	O
2994	O
,	O
and	O
there	O
's	O
a	O
GPLed	O
implementation	O
by	O
Hironobu	O
Suzuki	O
(	O
used	O
by	O
,	O
e.g.	O
</s>
<s>
Scramdisk	B-Application
)	O
.	O
</s>
<s>
MISTY1	B-Algorithm
is	O
a	O
Feistel	B-Algorithm
network	I-Algorithm
with	O
a	O
variable	O
number	O
of	O
rounds	O
(	O
any	O
multiple	O
of	O
4	O
)	O
,	O
though	O
8	O
are	O
recommended	O
.	O
</s>
<s>
MISTY1	B-Algorithm
has	O
an	O
innovative	O
recursive	O
structure	O
;	O
the	O
round	O
function	O
itself	O
uses	O
a	O
3-round	O
Feistel	B-Algorithm
network	I-Algorithm
.	O
</s>
<s>
MISTY1	B-Algorithm
claims	O
to	O
be	O
provably	O
secure	O
against	O
linear	O
and	O
differential	O
cryptanalysis	O
.	O
</s>
<s>
KASUMI	B-Algorithm
is	O
a	O
successor	O
of	O
the	O
MISTY1	B-Algorithm
cipher	O
which	O
was	O
supposed	O
to	O
be	O
stronger	O
than	O
MISTY1	B-Algorithm
and	O
has	O
been	O
adopted	O
as	O
the	O
standard	O
encryption	O
algorithm	O
for	O
European	O
mobile	O
phones	O
.	O
</s>
<s>
In	O
2005	O
,	O
KASUMI	B-Algorithm
was	O
broken	O
,	O
and	O
in	O
2010	O
a	O
new	O
paper	O
was	O
published	O
(	O
explained	O
below	O
)	O
detailing	O
a	O
practical	O
attack	O
on	O
the	O
cipher	O
;	O
see	O
the	O
article	O
for	O
more	O
details	O
.	O
</s>
<s>
In	O
the	O
paper	O
"	O
Block	O
Ciphers	O
and	O
Stream	O
Ciphers	O
"	O
by	O
Alex	O
Biryukov	O
,	O
it	O
is	O
noted	O
that	O
KASUMI	B-Algorithm
,	O
also	O
termed	O
A5/3	B-Algorithm
,	O
is	O
a	O
strengthened	O
version	O
of	O
block	O
cipher	O
MISTY1	B-Algorithm
running	O
in	O
a	O
Counter	O
mode	O
.	O
</s>
<s>
However	O
,	O
in	O
2010	O
Dunkelman	O
,	O
Keller	O
,	O
and	O
Shamir	O
showed	O
that	O
KASUMI	B-Algorithm
is	O
not	O
as	O
strong	O
as	O
MISTY1	B-Algorithm
;	O
the	O
KASUMI	B-Algorithm
attack	O
will	O
not	O
work	O
against	O
MISTY1	B-Algorithm
.	O
</s>
