<s>
The	O
Certificate	B-Protocol
Management	I-Protocol
Protocol	I-Protocol
(	O
CMP	O
)	O
is	O
an	O
Internet	O
protocol	O
standardized	O
by	O
the	O
IETF	O
used	O
for	O
obtaining	O
X.509	O
digital	O
certificates	O
in	O
a	O
public	B-Architecture
key	I-Architecture
infrastructure	I-Architecture
(	O
PKI	O
)	O
.	O
</s>
<s>
CMP	O
messages	O
are	O
self-contained	O
,	O
which	O
,	O
as	O
opposed	O
to	O
EST	B-Protocol
,	O
makes	O
the	O
protocol	O
independent	O
of	O
the	O
transport	O
mechanism	O
and	O
provides	O
end-to-end	O
security	O
.	O
</s>
<s>
CMP	O
messages	O
are	O
encoded	O
in	O
ASN.1	B-Protocol
,	O
using	O
the	O
DER	O
method	O
.	O
</s>
<s>
The	O
only	O
other	O
protocol	O
so	O
far	O
using	O
CRMF	O
is	O
Certificate	B-Protocol
Management	I-Protocol
over	I-Protocol
CMS	I-Protocol
(	O
CMC	O
)	O
,	O
described	O
in	O
.	O
</s>
<s>
In	O
a	O
public	B-Architecture
key	I-Architecture
infrastructure	I-Architecture
(	O
PKI	O
)	O
,	O
so-called	O
end	O
entities	O
(	O
EEs	O
)	O
act	O
as	O
CMP	O
client	O
,	O
requesting	O
one	O
or	O
more	O
certificates	O
for	O
themselves	O
from	O
a	O
certificate	B-Architecture
authority	I-Architecture
(	O
CA	B-Architecture
)	O
,	O
which	O
issues	O
the	O
legal	O
certificates	O
and	O
acts	O
as	O
a	O
CMP	O
server	O
.	O
</s>
<s>
Using	O
a	O
"	O
cross-certification	O
request	O
"	O
a	O
CA	B-Architecture
can	O
get	O
a	O
certificate	O
signed	O
by	O
another	O
CA	B-Architecture
.	O
</s>
<s>
Self-contained	O
messages	O
with	O
protection	O
independent	O
of	O
transfer	O
mechanism	O
-	O
as	O
opposed	O
to	O
related	O
protocols	O
EST	B-Protocol
and	O
SCEP	B-Protocol
,	O
this	O
supports	O
end-to-end	O
security	O
.	O
</s>
<s>
Full	O
certificate	O
life-cycle	O
support	O
:	O
an	O
end	O
entity	O
can	O
utilize	O
CMP	O
to	O
obtain	O
certificates	O
from	O
a	O
CA	B-Architecture
,	O
request	O
updates	O
for	O
them	O
,	O
and	O
also	O
get	O
them	O
revoked	O
.	O
</s>
<s>
In	O
case	O
an	O
end	O
entity	O
has	O
lost	O
its	O
private	O
key	O
and	O
it	O
is	O
stored	O
by	O
the	O
CA	B-Architecture
,	O
it	O
might	O
be	O
recovered	O
by	O
requesting	O
a	O
"	O
key	O
pair	O
recovery	O
"	O
.	O
</s>
<s>
There	O
are	O
various	O
further	O
types	O
of	O
requests	O
possible	O
,	O
for	O
instance	O
to	O
retrieve	O
CA	B-Architecture
certificates	I-Architecture
and	O
to	O
obtain	O
PKI	O
parameters	O
and	O
preferences	O
of	O
the	O
server	O
side	O
.	O
</s>
<s>
CMP	O
messages	O
are	O
usually	O
transferred	O
using	O
HTTP	B-Protocol
,	O
but	O
any	O
reliable	O
means	O
of	O
transportation	O
can	O
be	O
used	O
.	O
</s>
<s>
Encapsulated	O
in	O
HTTP	B-Protocol
messages	O
,	O
optionally	O
using	O
TLS	O
(	O
HTTPS	B-Protocol
)	O
for	O
additional	O
protection	O
.	O
</s>
<s>
Encapsulated	O
in	O
CoAP	B-Device
messages	O
,	O
optionally	O
using	O
DTLS	B-Protocol
for	O
additional	O
protection	O
.	O
</s>
<s>
TCP	B-Protocol
or	O
any	O
other	O
reliable	O
,	O
connection-oriented	O
transport	O
protocol	O
.	O
</s>
<s>
As	O
a	O
file	B-Operating_System
,	O
e.g.	O
,	O
over	O
FTP	B-Protocol
or	O
SCP	B-Protocol
.	O
</s>
<s>
By	O
E-Mail	O
,	O
using	O
the	O
MIME	B-Protocol
encoding	O
standard	O
.	O
</s>
<s>
The	O
Content-Type	B-Application
used	O
is	O
application/pkixcmp	O
;	O
older	O
versions	O
of	O
the	O
draft	O
used	O
application/pkixcmp	O
-poll	O
,	O
application/x	O
-pkixcmp	O
or	O
application/x	O
-pkixcmp-poll	O
.	O
</s>
<s>
OpenSSL	B-Language
version	O
3.0	O
includes	O
extensive	O
CMP	O
support	O
in	O
C	O
.	O
</s>
<s>
cryptlib	B-Language
provides	O
CMP	O
support	O
.	O
</s>
<s>
EJBCA	B-Language
,	O
a	O
CA	B-Architecture
software	O
,	O
implements	O
a	O
subset	O
of	O
the	O
CMP	O
functions	O
.	O
</s>
