<s>
GSM	B-Protocol
03.48	I-Protocol
is	O
a	O
protocol	O
used	O
to	O
exchange	O
secured	O
packets	B-Protocol
between	O
an	O
entity	O
in	O
a	O
GSM	O
PLMN	O
and	O
an	O
entity	O
in	O
the	O
SIM	O
card	O
.	O
</s>
<s>
Secured	O
packets	B-Protocol
contain	O
application	O
messages	O
to	O
which	O
certain	O
mechanisms	O
according	O
to	O
GSM	B-Protocol
03.48	I-Protocol
have	O
been	O
applied	O
.	O
</s>
<s>
The	O
generic	O
part	O
on	O
packet	B-Protocol
structure	O
has	O
been	O
transferred	O
to	O
SCP	O
(	O
ETSI	O
TS	O
102	O
225	O
)	O
.	O
</s>
<s>
The	O
resulting	O
structure	O
is	O
here	O
referred	O
to	O
as	O
the	O
(	O
Secured	O
)	O
Command	O
Packet	B-Protocol
.	O
</s>
<s>
Under	O
normal	O
circumstances	O
the	O
Receiving	O
Entity	O
receives	O
the	O
Command	O
Packet	B-Protocol
and	O
unpacks	O
it	O
according	O
to	O
the	O
security	O
parameters	O
indicated	O
in	O
the	O
Command	O
Header	O
.	O
</s>
<s>
If	O
so	O
indicated	O
in	O
the	O
Command	O
Header	O
,	O
the	O
Receiving	O
Entity	O
shall	O
create	O
a	O
(	O
Secured	O
)	O
Response	O
Packet	B-Protocol
.	O
</s>
<s>
The	O
Response	O
Packet	B-Protocol
consists	O
of	O
a	O
Security	O
Header	O
(	O
the	O
Response	O
Header	O
)	O
and	O
optionally	O
,	O
application	O
specific	O
data	O
supplied	O
by	O
the	O
Receiving	O
Application	O
.	O
</s>
<s>
Both	O
the	O
Response	O
Header	O
and	O
the	O
application	O
specific	O
data	O
are	O
secured	O
using	O
the	O
security	O
mechanisms	O
indicated	O
in	O
the	O
received	O
Command	O
Packet	B-Protocol
.	O
</s>
<s>
The	O
Response	O
Packet	B-Protocol
will	O
be	O
returned	O
to	O
the	O
Sending	O
Entity	O
,	O
subject	O
to	O
constraints	O
in	O
the	O
transport	B-Architecture
layer	I-Architecture
,	O
(	O
e.g.	O
</s>
