<s>
The	O
Lightweight	O
Encryption	O
Algorithm	O
(	O
also	O
known	O
as	O
LEA	B-Algorithm
)	O
is	O
a	O
128-bit	O
block	O
cipher	O
developed	O
by	O
South	O
Korea	O
in	O
2013	O
to	O
provide	O
confidentiality	O
in	O
high-speed	O
environments	O
such	O
as	O
big	B-Application
data	I-Application
and	O
cloud	B-Architecture
computing	I-Architecture
,	O
as	O
well	O
as	O
lightweight	O
environments	O
such	O
as	O
IoT	B-Operating_System
devices	I-Operating_System
and	O
mobile	O
devices	O
.	O
</s>
<s>
LEA	B-Algorithm
has	O
three	O
different	O
key	O
lengths	O
:	O
128	O
,	O
192	O
,	O
and	O
256	O
bits	O
.	O
</s>
<s>
LEA	B-Algorithm
encrypts	O
data	O
about	O
1.5	O
to	O
2	O
times	O
faster	O
than	O
AES	B-Algorithm
,	O
the	O
most	O
widely	O
used	O
block	O
cipher	O
in	O
various	O
software	O
environments	O
.	O
</s>
<s>
LEA	B-Algorithm
is	O
one	O
of	O
the	O
cryptographic	O
algorithms	O
approved	O
by	O
the	O
Korean	O
Cryptographic	O
Module	O
Validation	O
Program	O
(	O
KCMVP	O
)	O
and	O
is	O
the	O
national	O
standard	O
of	O
Republic	O
of	O
Korea	O
(	O
KS	O
X	O
3246	O
)	O
.	O
</s>
<s>
LEA	B-Algorithm
is	O
included	O
in	O
the	O
ISO/IEC	O
29192-2:2019	O
standard	O
(	O
Information	O
security	O
-	O
Lightweight	O
cryptography	O
-	O
Part	O
2	O
:	O
Block	O
ciphers	O
)	O
.	O
</s>
<s>
The	O
block	O
cipher	O
LEA	B-Algorithm
consisting	O
of	O
ARX	O
operations	O
(	O
modular	O
Addition	O
:	O
,	O
bitwise	O
Rotation	O
:	O
,	O
,	O
and	O
bitwise	O
XOR	O
)	O
for	O
32-bit	O
words	O
processes	O
data	O
blocks	O
of	O
128	O
bits	O
and	O
has	O
three	O
different	O
key	O
lengths	O
:	O
128	O
,	O
192	O
,	O
and	O
256	O
bits	O
.	O
</s>
<s>
LEA	B-Algorithm
with	O
a	O
128-bit	O
key	O
,	O
LEA	B-Algorithm
with	O
a	O
192-bit	O
key	O
,	O
and	O
LEA	B-Algorithm
with	O
a	O
256-bit	O
key	O
are	O
referred	O
to	O
as	O
“	O
LEA-128	O
”	O
,	O
“	O
LEA-192	O
”	O
,	O
and	O
“	O
LEA-256	O
”	O
,	O
respectively	O
.	O
</s>
<s>
The	O
number	O
of	O
rounds	O
is	O
24	O
for	O
LEA-128	O
,	O
28	O
for	O
LEA-192	O
,	O
and	O
32	O
for	O
LEA-256	O
.	O
</s>
<s>
Here	O
is	O
the	O
number	O
of	O
rounds	O
for	O
the	O
LEA	B-Algorithm
algorithm	O
.	O
</s>
<s>
The	O
key	O
schedule	O
of	O
LEA	B-Algorithm
supports	O
128	O
,	O
192	O
,	O
and	O
256-bit	O
keys	O
and	O
outputs	O
192-bit	O
round	O
keys	O
(	O
)	O
for	O
the	O
data	O
processing	O
part	O
.	O
</s>
<s>
The	O
key	O
schedule	O
for	O
LEA-128	O
takes	O
and	O
four	O
32-bit	O
constants	O
(	O
)	O
as	O
inputs	O
and	O
outputs	O
twenty-four	O
192-bit	O
round	O
keys	O
(	O
)	O
.	O
</s>
<s>
The	O
key	O
schedule	O
operation	O
for	O
LEA-128	O
is	O
as	O
follows	O
:	O
</s>
<s>
The	O
key	O
schedule	O
for	O
LEA-192	O
takes	O
and	O
six	O
32-bit	O
constants	O
(	O
)	O
as	O
inputs	O
and	O
outputs	O
twenty-eight	O
192-bit	O
round	O
keys	O
(	O
)	O
.	O
</s>
<s>
The	O
key	O
schedule	O
operation	O
for	O
LEA-192	O
is	O
as	O
follows	O
:	O
</s>
<s>
The	O
key	O
schedule	O
for	O
LEA-192	O
takes	O
and	O
eight	O
32-bit	O
constants	O
(	O
)	O
as	O
inputs	O
and	O
outputs	O
thirty-two	O
192-bit	O
round	O
keys	O
(	O
)	O
.	O
</s>
<s>
The	O
key	O
schedule	O
operation	O
for	O
LEA-256	O
is	O
as	O
follows	O
:	O
</s>
<s>
As	O
of	O
2019	O
,	O
no	O
successful	O
attack	O
on	O
full-round	O
LEA	B-Algorithm
is	O
known	O
.	O
</s>
<s>
The	O
best	O
published	O
attacks	O
on	O
LEA	B-Algorithm
in	O
the	O
standard	O
attack	O
model	O
(	O
CPA/CCA	O
with	O
unknown	O
key	O
)	O
are	O
boomerang	O
attacks	O
and	O
differential	O
linear	O
attacks	O
.	O
</s>
<s>
LEA	B-Algorithm
has	O
very	O
good	O
performance	O
in	O
a	O
general-purpose	O
software	O
environment	O
.	O
</s>
<s>
In	O
particular	O
,	O
it	O
is	O
possible	O
to	O
encrypt	O
at	O
a	O
rate	O
of	O
about	O
1.5	O
to	O
2	O
times	O
on	O
average	O
,	O
compared	O
to	O
AES	B-Algorithm
,	O
the	O
most	O
widely	O
used	O
block	O
cipher	O
in	O
various	O
software	O
environments	O
.	O
</s>
<s>
The	O
tables	O
below	O
compare	O
the	O
performance	O
of	O
LEA	B-Algorithm
and	O
AES	B-Algorithm
using	O
FELICS	O
(	O
Fair	O
Evaluation	O
of	O
Lightweight	O
Cryptographic	O
Systems	O
)	O
,	O
a	O
benchmarking	O
framework	O
for	O
evaluation	O
of	O
software	O
implementations	O
of	O
lightweight	O
cryptographic	O
primitives	O
.	O
</s>
<s>
Test	O
vectors	O
for	O
LEA	B-Algorithm
for	O
each	O
key	O
length	O
are	O
as	O
follows	O
.	O
</s>
<s>
LEA	B-Algorithm
is	O
free	O
for	O
any	O
use	O
:	O
public	O
or	O
private	O
,	O
commercial	O
or	O
non-commercial	O
.	O
</s>
<s>
The	O
source	O
code	O
for	O
distribution	O
of	O
LEA	B-Algorithm
implemented	O
in	O
C	B-Language
,	O
Java	B-Language
,	O
and	O
Python	B-Language
can	O
be	O
downloaded	O
from	O
KISA	O
's	O
website	O
.	O
</s>
<s>
In	O
addition	O
,	O
LEA	B-Algorithm
is	O
contained	O
in	O
Crypto++	O
library	O
,	O
a	O
free	O
C++	B-Language
class	O
library	O
of	O
cryptographic	O
schemes	O
.	O
</s>
<s>
LEA	B-Algorithm
is	O
one	O
of	O
the	O
cryptographic	O
algorithms	O
approved	O
by	O
the	O
Korean	O
Cryptographic	O
Module	O
Validation	O
Program	O
(	O
KCMVP	O
)	O
.	O
</s>
<s>
LEA	B-Algorithm
is	O
included	O
in	O
the	O
following	O
standards	O
.	O
</s>
