<s>
An	O
rpmsg	B-Operating_System
file	O
is	O
a	O
restricted-permission	O
message	O
with	O
an	O
extension	O
of	O
rpmsg	B-Operating_System
.	O
</s>
<s>
The	O
rpmsg	B-Operating_System
file	O
is	O
created	O
by	O
writing	O
body	O
,	O
attachments	O
and	O
images	O
to	O
a	O
compound	O
file	O
and	O
then	O
compressing	O
and	O
encrypting	O
it	O
to	O
create	O
a	O
BLOB	B-General_Concept
:	O
the	O
rpmsg	B-Operating_System
file	O
.	O
</s>
<s>
This	O
resulting	O
file	O
is	O
named	O
message.rpmsg	O
and	O
is	O
included	O
as	O
an	O
attachment	O
to	O
a	O
normal	O
Outlook	O
message	O
.	O
</s>
<s>
This	O
can	O
be	O
implemented	O
by	O
parsing	O
the	O
file	O
structure	O
in-code	O
,	O
as	O
currently	O
the	O
MSIPC	O
SDK	O
,	O
normally	O
used	O
by	O
applications	O
to	O
protect	O
and	O
decrypt	O
content	O
protected	O
with	O
Azure	O
Information	O
Protection	O
,	O
does	O
not	O
provide	O
native	O
functionality	O
to	O
encode	O
and	O
decode	O
the	O
RPMSG	B-Operating_System
format	O
.	O
</s>
<s>
This	O
certificate	O
is	O
included	O
within	O
the	O
encrypted	O
rpmsg	B-Operating_System
file	O
.	O
</s>
<s>
When	O
the	O
rpmsg	B-Operating_System
attachment	O
is	O
decrypted	O
the	O
enclosed	O
'	O
Publishing	O
License	O
 '	O
is	O
sent	O
to	O
the	O
information	O
protection	O
service	O
pointed	O
to	O
by	O
its	O
header	O
in	O
order	O
to	O
obtain	O
a	O
Use	O
License	O
.	O
</s>
<s>
An	O
rpmsg	B-Operating_System
file	O
consists	O
of	O
a	O
magic	O
number	O
followed	O
by	O
one	O
or	O
more	O
data	O
chunks	O
.	O
</s>
<s>
The	O
concatenated	O
data	O
chunks	O
form	O
a	O
single	O
data	O
stream	O
compressed	O
using	O
the	O
DEFLATE	B-Algorithm
algorithm	O
.	O
</s>
