<s>
Crypto	B-Application
API	I-Application
is	O
a	O
cryptography	O
framework	B-Architecture
in	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
for	O
various	O
parts	O
of	O
the	O
kernel	B-Operating_System
that	O
deal	O
with	O
cryptography	O
,	O
such	O
as	O
IPsec	B-Protocol
and	O
dm-crypt	O
.	O
</s>
<s>
It	O
was	O
introduced	O
in	O
kernel	B-Operating_System
version	O
2.5.45	O
and	O
has	O
since	O
expanded	O
to	O
include	O
essentially	O
all	O
popular	O
block	O
ciphers	O
and	O
hash	B-Error_Name
functions	I-Error_Name
.	O
</s>
<s>
Many	O
platforms	O
that	O
provide	O
hardware	O
acceleration	O
of	O
AES	B-Algorithm
encryption	I-Algorithm
expose	O
this	O
to	O
programs	O
through	O
an	O
extension	O
of	O
the	O
instruction	B-General_Concept
set	I-General_Concept
architecture	I-General_Concept
(	O
ISA	O
)	O
of	O
the	O
various	O
chipsets	O
(	O
e.g.	O
</s>
<s>
AES	B-Algorithm
instruction	I-Algorithm
set	I-Algorithm
for	O
x86	B-Operating_System
)	O
.	O
</s>
<s>
With	O
this	O
sort	O
of	O
implementation	O
any	O
program	O
(	O
kernel-mode	B-Operating_System
or	O
user-space	B-Operating_System
)	O
may	O
utilize	O
these	O
features	O
directly	O
.	O
</s>
<s>
Some	O
platforms	O
,	O
such	O
as	O
the	O
ARM	O
Kirkwood	O
SheevaPlug	B-Application
and	O
AMD	B-Device
Geode	I-Device
processors	O
,	O
however	O
,	O
are	O
not	O
implemented	O
as	O
ISA	O
extensions	O
,	O
and	O
are	O
only	O
accessible	O
through	O
kernel-mode	B-Operating_System
drivers	O
.	O
</s>
<s>
In	O
order	O
for	O
user-mode	B-Operating_System
applications	O
that	O
utilize	O
encryption	O
,	O
such	O
as	O
wolfSSL	B-Protocol
,	O
OpenSSL	B-Language
or	O
GnuTLS	B-Application
,	O
to	O
take	O
advantage	O
of	O
such	O
acceleration	O
,	O
they	O
must	O
interface	O
with	O
the	O
kernel	B-Operating_System
.	O
</s>
<s>
A	O
netlink-based	O
interface	O
that	O
adds	O
an	O
AF_ALG	O
address	O
family	O
;	O
it	O
was	O
merged	O
into	O
version	O
2.6.38	O
of	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
mainline	O
.	O
</s>
<s>
There	O
was	O
once	O
a	O
plugin	O
to	O
OpenSSL	B-Language
to	O
support	O
AF_ALG	O
,	O
which	O
has	O
been	O
submitted	O
for	O
merging	O
.	O
</s>
<s>
In	O
version	O
1.1.0	O
,	O
OpenSSL	B-Language
landed	O
another	O
patch	O
for	O
AF_ALG	O
contributed	O
by	O
Intel	O
.	O
</s>
<s>
The	O
OpenBSD	O
Cryptographic	O
Framework	B-Architecture
/dev/crypto	O
interface	O
of	O
OpenBSD	O
was	O
ported	O
to	O
Linux	B-Operating_System
,	O
but	O
never	O
merged	O
.	O
</s>
