<s>
A	O
security	B-Protocol
association	I-Protocol
(	O
SA	O
)	O
is	O
the	O
establishment	O
of	O
shared	O
security	O
attributes	O
between	O
two	O
network	B-Architecture
entities	O
to	O
support	O
secure	O
communication	O
.	O
</s>
<s>
An	O
SA	O
may	O
include	O
attributes	O
such	O
as	O
:	O
cryptographic	O
algorithm	O
and	O
mode	O
;	O
traffic	O
encryption	O
key	O
;	O
and	O
parameters	O
for	O
the	O
network	B-Architecture
data	O
to	O
be	O
passed	O
over	O
the	O
connection	O
.	O
</s>
<s>
The	O
framework	O
for	O
establishing	O
security	B-Protocol
associations	I-Protocol
is	O
provided	O
by	O
the	O
Internet	B-Protocol
Security	I-Protocol
Association	I-Protocol
and	I-Protocol
Key	I-Protocol
Management	I-Protocol
Protocol	I-Protocol
(	O
ISAKMP	B-Protocol
)	O
.	O
</s>
<s>
Protocols	O
such	O
as	O
Internet	B-Protocol
Key	I-Protocol
Exchange	I-Protocol
(	O
IKE	O
)	O
and	O
Kerberized	B-Protocol
Internet	I-Protocol
Negotiation	I-Protocol
of	I-Protocol
Keys	I-Protocol
(	O
KINK	O
)	O
provide	O
authenticated	O
keying	O
material	O
.	O
</s>
<s>
An	O
SA	O
is	O
a	O
simplex	O
(	O
one-way	O
channel	O
)	O
and	O
logical	O
connection	O
which	O
endorses	O
and	O
provides	O
a	O
secure	O
data	O
connection	O
between	O
the	O
network	B-Architecture
devices	O
.	O
</s>
<s>
Take	O
,	O
for	O
example	O
,	O
a	O
mobile	B-General_Concept
subscriber	O
and	O
a	O
base	O
station	O
.	O
</s>
<s>
Therefore	O
,	O
each	O
service	O
may	O
have	O
different	O
service	O
primitives	O
,	O
such	O
as	O
a	O
data	O
encryption	O
algorithm	O
,	O
public	B-Application
key	I-Application
,	O
or	O
initialization	O
vector	O
.	O
</s>
<s>
To	O
make	O
things	O
easier	O
,	O
all	O
of	O
this	O
security	O
information	O
is	O
grouped	O
logically	O
,	O
and	O
the	O
logical	O
group	O
itself	O
is	O
a	O
Security	B-Protocol
Association	I-Protocol
.	O
</s>
<s>
So	O
both	O
the	O
base	O
station	O
and	O
mobile	B-General_Concept
subscriber	O
will	O
share	O
the	O
SAID	O
,	O
and	O
they	O
will	O
derive	O
all	O
the	O
security	O
parameters	O
.	O
</s>
