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# How to use the pycrate ASN.1 runtime
In this section, we will see how to use the ASN.1 runtime with already compiled
specifications from the
[
pycrate_asn1dir/
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/
)
[
pycrate_asn1dir/
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/
)
directory, with basic examples.
...
...
@@ -19,7 +19,7 @@ The ASN.1 runtime is then in charge, together with the compiled specification, t
encode values for those ASN.1 objects to buffers, and decode buffers to values.
The pycrate ASN.1 runtime, as defined in
[
pycrate_asn1rt
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1rt/
)
,
[
pycrate_asn1rt
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1rt/
)
,
currently implements the following encoders / decoders:
-
the ASN.1 textual syntax, with
*to_asn1()*
/
*from_asn1()*
methods
-
the unaligned Packed Encoding Rules (UPER), with
*to_uper()*
/
*from_uper()*
methods
...
...
@@ -352,15 +352,15 @@ Pycrate provides two different modules to handle both protocols:
-
the UMTS RRC protocol is defined in the
[
TS 25.331
](
http://www.3gpp.org/DynaReport/25331.htm
)
3GPP specification;
the ASN.1 definition is available in the directory
[
pycrate_asn1dir/3GPP_UTRAN_RRC_25331/
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/3GPP_UTRAN_RRC_25331/
)
[
pycrate_asn1dir/3GPP_UTRAN_RRC_25331/
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/3GPP_UTRAN_RRC_25331/
)
and the corresponding Python modules are compiled in the file
[
pycrate_asn1dir/RRC3G.py
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/RRC3G.py
)
.
[
pycrate_asn1dir/RRC3G.py
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/RRC3G.py
)
.
-
the LTE RRC protocol is defined in the
[
TS 36.331
](
http://www.3gpp.org/DynaReport/36331.htm
)
3GPP specification;
the ASN.1 definition is available in the directory
[
pycrate_asn1dir/3GPP_EUTRAN_RRC_36331/
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/3GPP_EUTRAN_RRC_36331/
)
[
pycrate_asn1dir/3GPP_EUTRAN_RRC_36331/
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/3GPP_EUTRAN_RRC_36331/
)
and the corresponding Python modules are compiled in the file
[
pycrate_asn1dir/RRCLTE.py
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/RRCLTE.py
)
.
[
pycrate_asn1dir/RRCLTE.py
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/RRCLTE.py
)
.
Both specifications provided are from the 3GPP release 13 (0xd), however, it is possible
to easily upgrade or downgrade them thanks to the
*extract.py*
scripts provided in the ASN.1 definition
...
...
@@ -698,9 +698,9 @@ to drive mobile phones connecting to the 3G radio access network, from the core
stand-point. The protocol is specified by the 3GPP standard
[
TS 25.413
](
http://www.3gpp.org/DynaReport/25413.htm
)
, the ASN.1 definition is available
in the directory
[
pycrate_asn1dir/3GPP_UTRAN_RANAP_25413/
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/3GPP_UTRAN_RANAP_25413/
)
[
pycrate_asn1dir/3GPP_UTRAN_RANAP_25413/
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/3GPP_UTRAN_RANAP_25413/
)
and the corresponding Python modules are in the compiled file
[
pycrate_asn1dir/RANAP.py
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/RANAP.py
)
.
[
pycrate_asn1dir/RANAP.py
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/RANAP.py
)
.
Contrary to RRC protocols, there is a single RANAP ASN.1 object to encode and decode all
the messages that can be exchanged with it: the
*RANAP-PDU*
defined in the
*RANAP-PDU-Descriptions*
...
...
@@ -963,12 +963,12 @@ And here is an example on how to encode an uplink RANAP Direct Transfer message:
In order to go further, we can read the source code of the ongoing effort to build a 3G
core network, available in the directory
[
pycrate_corenet
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_corenet/
)
.
[
pycrate_corenet
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_corenet/
)
.
There is a generic Python module
*LinkSigProc*
to help with the procedures defined
in this kind of RPC-like protocol:
[
pycrate_corenet/ProcProto.py
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_corenet/ProcProto.py
)
,
[
pycrate_corenet/ProcProto.py
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_corenet/ProcProto.py
)
,
and some initial RANAP procedures defined here:
[
pycrate_corenet/ProcCNRanap.py
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_corenet/ProcCNRanap.py
)
.
[
pycrate_corenet/ProcCNRanap.py
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_corenet/ProcCNRanap.py
)
.
### S1AP
S1AP is the signaling protocol used between the MME in an LTE core network (also called an EPC)
...
...
@@ -977,9 +977,9 @@ and also mobile phones connecting to the 4G radio access network, from the core
The protocol is specified by the 3GPP standard
[
TS 36.413
](
http://www.3gpp.org/DynaReport/36413.htm
)
, the ASN.1 definition is available
in the directory
[
pycrate_asn1dir/3GPP_EUTRAN_S1AP_36413/
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/3GPP_EUTRAN_S1AP_36413/
)
[
pycrate_asn1dir/3GPP_EUTRAN_S1AP_36413/
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/3GPP_EUTRAN_S1AP_36413/
)
and the corresponding Python modules are in the file
[
pycrate_asn1dir/S1AP.py
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/S1AP.py
)
.
[
pycrate_asn1dir/S1AP.py
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/S1AP.py
)
.
S1AP and X2AP protocols are very similar to the existing 3G protocols (like RANAP).
There is a single top-level object to encode and decode all protocol's messages:
...
...
@@ -1125,36 +1125,36 @@ is from 1997.
The MAP specification can be found in the 3GPP standard
[
TS 29.002
](
http://www.3gpp.org/DynaReport/29002.htm
)
, the ASN.1 definition is available
in the directory
[
pycrate_asn1dir/3GPP_MAP_29002/
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/3GPP_MAP_29002/
)
[
pycrate_asn1dir/3GPP_MAP_29002/
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/3GPP_MAP_29002/
)
and the corresponding Python modules are in the compiled file
[
pycrate_asn1dir/MAP.py
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/MAP.py
)
.
[
pycrate_asn1dir/MAP.py
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/MAP.py
)
.
The CAP specification can be found in the 3GPP standard
[
TS 29.078
](
http://www.3gpp.org/DynaReport/29078.htm
)
, the ASN.1 definition is available
in the directory
[
pycrate_asn1dir/3GPP_CAP_29078/
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/3GPP_CAP_29078/
)
[
pycrate_asn1dir/3GPP_CAP_29078/
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/3GPP_CAP_29078/
)
and the corresponding Python modules are in the compiled file
[
pycrate_asn1dir/CAP.py
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/CAP.py
)
.
[
pycrate_asn1dir/CAP.py
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/CAP.py
)
.
The TCAP specification can be found in the ITU-T standard
[
Q.773
](
http://www.itu.int/rec/T-REC-Q.773-199706-I
)
, the ASN.1 definition is available
in the directory
[
pycrate_asn1dir/ITUT_Q773_1997-06/
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/ITUT_Q773_1997-06/
)
[
pycrate_asn1dir/ITUT_Q773_1997-06/
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/ITUT_Q773_1997-06/
)
and the corresponding Python modules are in the compiled file
[
pycrate_asn1dir/TCAP.py
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/TCAP.py
)
.
[
pycrate_asn1dir/TCAP.py
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/TCAP.py
)
.
The
*TCMessage*
object which corresponds to the structure of a TCAP message transporting MAP or CAP data
needs actually to be parameterized with higher level protocol definition. Moreover, the EXTERNAL object
used within the TCAP specification is from an older ASN.1 standard (the one from 1988)
and does not correspond to the EXTERNAL structure defined in the pycrate ASN.1 runtime.
For this reasons, two custom modules have been created:
-
[
pycrate_asn1dir/Pycrate-TCAP-MAP
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/Pycrate-TCAP-MAP/
)
-
[
pycrate_asn1dir/Pycrate-TCAP-MAP
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/Pycrate-TCAP-MAP/
)
with the corresponding compiled file
[
pycrate_asn1dir/TCAP_MAP.py
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/TCAP_MAP.py
)
[
pycrate_asn1dir/TCAP_MAP.py
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/TCAP_MAP.py
)
and the top-level object
*TCAP-MAP-Message*
-
[
pycrate_asn1dir/Pycrate-TCAP-CAP
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/Pycrate-TCAP-CAP/
)
-
[
pycrate_asn1dir/Pycrate-TCAP-CAP
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/Pycrate-TCAP-CAP/
)
with the corresponding compiled file
[
pycrate_asn1dir/TCAP_CAP.py
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/TCAP_CAP.py
)
;
[
pycrate_asn1dir/TCAP_CAP.py
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/TCAP_CAP.py
)
;
CAP has multiple top-level objects defined in the
*CAP-gsm*
and
*CAP-gprs*
modules.
All those protocols are using the ASN.1 BER encoding.
...
...
@@ -1358,9 +1358,9 @@ It is a set of 8 ASN.1 modules, which actually requires many other modules from
ITU-T specifications to be compiled.
The X.509 2016 ASN.1 module from ITU-T is available in the directory
[
pycrate_asn1dir/ITUT_X509_2016-10
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/ITUT_X509_2016-10/
)
[
pycrate_asn1dir/ITUT_X509_2016-10
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/ITUT_X509_2016-10/
)
and the corresponding Python module are in the compiled file
[
pycrate_asn1dir/X509_2016.py
](
https://github.com/
ANSSI-FR
/pycrate/blob/master/pycrate_asn1dir/X509_2016.py
)
[
pycrate_asn1dir/X509_2016.py
](
https://github.com/
p1sec
/pycrate/blob/master/pycrate_asn1dir/X509_2016.py
)
Few errors have been corrected compared to the archive of ASN.1 files provided by the
ITU-T web site for the specification to compile correctly.
...
...
...
...
