<s>
In	O
cryptography	O
,	O
key	B-Algorithm
wrap	I-Algorithm
constructions	O
are	O
a	O
class	O
of	O
symmetric	B-Algorithm
encryption	I-Algorithm
algorithms	O
designed	O
to	O
encapsulate	B-Algorithm
(	O
encrypt	O
)	O
cryptographic	O
key	O
material	O
.	O
</s>
<s>
The	O
Key	B-Algorithm
Wrap	I-Algorithm
algorithms	O
are	O
intended	O
for	O
applications	O
such	O
as	O
protecting	O
keys	O
while	O
in	O
untrusted	O
storage	O
or	O
transmitting	O
keys	O
over	O
untrusted	O
communications	O
networks	O
.	O
</s>
<s>
The	O
constructions	O
are	O
typically	O
built	O
from	O
standard	O
primitives	O
such	O
as	O
block	O
ciphers	O
and	O
cryptographic	B-Algorithm
hash	I-Algorithm
functions	I-Algorithm
.	O
</s>
<s>
Key	B-Algorithm
Wrap	I-Algorithm
may	O
be	O
considered	O
as	O
a	O
form	O
of	O
key	B-Algorithm
encapsulation	I-Algorithm
algorithm	O
,	O
although	O
it	O
should	O
not	O
be	O
confused	O
with	O
the	O
more	O
commonly	O
known	O
asymmetric	O
(	O
public-key	O
)	O
key	B-Algorithm
encapsulation	I-Algorithm
algorithms	O
(	O
e.g.	O
,	O
PSEC-KEM	O
)	O
.	O
</s>
<s>
Key	B-Algorithm
Wrap	I-Algorithm
algorithms	O
can	O
be	O
used	O
in	O
a	O
similar	O
application	O
:	O
to	O
securely	O
transport	O
a	O
session	O
key	O
by	O
encrypting	O
it	O
under	O
a	O
long-term	O
encryption	O
key	O
.	O
</s>
<s>
In	O
the	O
late	O
1990s	O
,	O
the	O
National	O
Institute	O
of	O
Standards	O
and	O
Technology	O
(	O
NIST	O
)	O
posed	O
the	O
"	O
Key	B-Algorithm
Wrap	I-Algorithm
"	O
problem	O
:	O
to	O
develop	O
secure	O
and	O
efficient	O
cipher-based	O
key	O
encryption	O
algorithms	O
.	O
</s>
<s>
Based	O
on	O
the	O
resulting	O
algorithms	O
,	O
the	O
design	O
requirements	O
appear	O
to	O
be	O
(	O
1	O
)	O
confidentiality	O
,	O
(	O
2	O
)	O
integrity	O
protection	O
(	O
authentication	O
)	O
,	O
(	O
3	O
)	O
efficiency	O
,	O
(	O
4	O
)	O
use	O
of	O
standard	O
(	O
approved	O
)	O
underlying	O
primitives	O
such	O
as	O
the	O
Advanced	B-Algorithm
Encryption	I-Algorithm
Standard	I-Algorithm
(	O
AES	B-Algorithm
)	O
and	O
the	O
Secure	O
Hash	B-Algorithm
Algorithm	O
(	O
SHA-1	B-Algorithm
)	O
,	O
and	O
(	O
5	O
)	O
consideration	O
of	O
additional	O
circumstances	O
(	O
e.g.	O
,	O
resilience	O
to	O
operator	O
error	O
,	O
low-quality	O
random	O
number	O
generators	O
)	O
.	O
</s>
<s>
Goals	O
(	O
3	O
)	O
and	O
(	O
5	O
)	O
are	O
particularly	O
important	O
,	O
given	O
that	O
many	O
widely	O
deployed	O
authenticated	B-Algorithm
encryption	I-Algorithm
algorithms	O
(	O
e.g.	O
,	O
AES-CCM	O
)	O
are	O
already	O
sufficient	O
to	O
accomplish	O
the	O
remaining	O
goals	O
.	O
</s>
<s>
TDKW	O
(	O
similar	O
to	O
AESKW	B-Algorithm
,	O
built	O
from	O
Triple	B-Algorithm
DES	I-Algorithm
rather	O
than	O
AES	B-Algorithm
)	O
.	O
</s>
<s>
Each	O
of	O
the	O
proposed	O
algorithms	O
can	O
be	O
considered	O
as	O
a	O
form	O
of	O
authenticated	B-Algorithm
encryption	I-Algorithm
algorithm	O
providing	O
confidentiality	O
for	O
highly	O
entropic	O
messages	O
such	O
as	O
cryptographic	O
keys	O
.	O
</s>
<s>
The	O
AES	B-Algorithm
Key	I-Algorithm
Wrap	O
Specification	O
,	O
AESKW	B-Algorithm
,	O
TDKW	O
,	O
and	O
AKW1	O
are	O
intended	O
to	O
maintain	O
confidentiality	O
under	O
adaptive	O
chosen	O
ciphertext	O
attacks	O
,	O
while	O
the	O
AKW2	O
algorithm	O
is	O
designed	O
to	O
be	O
secure	O
only	O
under	O
known-plaintext	O
(	O
or	O
weaker	O
)	O
attacks	O
.	O
</s>
<s>
AESKW	B-Algorithm
,	O
TDKW	O
and	O
AKW2	O
also	O
provide	O
the	O
ability	O
to	O
authenticate	O
cleartext	O
"	O
header	O
"	O
,	O
an	O
associated	O
block	O
of	O
data	O
that	O
is	O
not	O
encrypted	O
.	O
</s>
<s>
new	O
AES	B-Algorithm
mode	O
in	O
.	O
</s>
