laforge has submitted this change. (
https://gerrit.osmocom.org/c/pysim/+/42237?usp=email )
Change subject: docs/smpp-ota-tool: Add documentation/tutorial
......................................................................
docs/smpp-ota-tool: Add documentation/tutorial
We already have documentation that explains how to run pySim-smpp2sim.
With smpp-ota-tool we now have a counterpart for pySim-smpp2sim, so
let's add documentation for this tool as well.
Related: SYS#7881
Change-Id: If0d18a263f5a6dc035b90f5c5c6a942d46bbba49
---
M docs/index.rst
A docs/smpp-ota-tool.rst
M docs/smpp2sim.rst
3 files changed, 182 insertions(+), 0 deletions(-)
Approvals:
laforge: Looks good to me, approved
Jenkins Builder: Verified
diff --git a/docs/index.rst b/docs/index.rst
index 92be830..a6ed7b9 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -48,6 +48,7 @@
sim-rest
suci-keytool
saip-tool
+ smpp-ota-tool
Indices and tables
diff --git a/docs/smpp-ota-tool.rst b/docs/smpp-ota-tool.rst
new file mode 100644
index 0000000..beb494a
--- /dev/null
+++ b/docs/smpp-ota-tool.rst
@@ -0,0 +1,179 @@
+smpp-ota-tool
+=============
+
+The `smpp-ota-tool` allows users to send OTA SMS messages containing APDU
scripts (RFM, RAM) via an SMPP server. The
+intended audience are developers who want to test/evaluate the OTA SMS
interface of a SIM/UICC/eUICC. `smpp-ota-tool`
+is intended to be used as a companion tool for :ref:`pySim-smpp2sim`, however
it should be usable on any other SMPP
+server (such as a production SMSC of a live cellular network) as well.
+
+From the technical perspective `smpp-ota-tool` takes the role of an SMPP ESME.
It takes care of the encoding, encryption
+and checksumming (signing) of the RFM/RAM OTA SMS and eventually submits it to
the SMPP server. The program then waits
+for a response. The response is automatically parsed and printed on stdout.
This makes the program also suitable to be
+called from shell scripts.
+
+.. note:: In the following we will we will refer to `SIM` as one of the
following: `SIM`, `USIM`, `ISIM`, `UICC`,
+ `eUICC`, `eSIM`.
+
+Applying OTA keys
+~~~~~~~~~~~~~~~~~
+
+Depending on the `SIM` type you will receive one or more sets of keys which
you can use to communicate with the `SIM`
+through a secure channel protocol. When using the OTA SMS method, the SCP80
protocol is used and it therefore crucial
+to use a keyset that is actually suitable for SCP80.
+
+A keyset usually consists of three keys:
+
+#. KIC: the key used for ciphering (encryption/decryption)
+#. KID: the key used to compute a cryptographic checksum (signing)
+#. KIK: the key used to encrypt/decrypt key material (key rotation, adding of
new keys)
+
+From the transport security perspective, only KIC and KID are relevant. The
KIK (also referenced as "Data Encryption
+Key", DEK) is only used when keys are rotated or new keys are added (see also
ETSI TS 102 226, section 8.2.1.5).
+
+When the keyset is programmed into the security domain of the `SIM`, it is
tied to a specific cryptographic algorithm
+(3DES, AES128 or AES256) and a so called Key Version Number (KVN). The term
"Key Version Number" is misleading, since
+it is actually not a version number. It is a unique identifier of a certain
keyset which also identifies for which
+secure channel protocol the keyset may be used. Keysets with a KVN from 1-15
(``0x01``-``0x0F``) are suitable for SCP80.
+This means that it is not only important to know just the KIC/KID/KIK keys.
Also the related algorithms and the KVN
+numbers must be known.
+
+.. note:: SCP80 keysets typically start counting from 1 upwards. Typical
configurations use a set of 3 keysets with
+ KVN numbers 1-3.
+
+Addressing an Application
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When communicating with a specific application on a `SIM` via SCP80, it is
important to address that application with
+the correct parameters. The following two parameters must be known in advance:
+
+#. TAR: The Toolkit Application Reference (TAR) number is a three byte value
that uniquely addresses an application
+ on the `SIM`. The exact values may vary (see also ETSI TS 101 220, Table
D.1).
+#. MSL: The Minimum Security Level (MSL) is a bit-field that dictates which of
the security measures encoded in the
+ SPI are mandatory (see also ETSI TS 102 225, section 5.1.1).
+
+A practical example
+~~~~~~~~~~~~~~~~~~~
+
+.. note:: This tutorial assumes that pySim-smpp2sim is running on the local
machine with its default parameters.
+ See also :ref:`pySim-smpp2sim`.
+
+Let's assume that an OTA SMS shall be sent to the SIM RFM application of an
sysmoISIM-SJA2. What we want to do is to
+select DF.GSM and to get the select response back.
+
+We have received the following key material from the `SIM` vendor:
+
+::
+
+ KIC1: F09C43EE1A0391665CC9F05AF4E0BD10
+ KID1: 01981F4A20999F62AF99988007BAF6CA
+ KIK1: 8F8AEE5CDCC5D361368BC45673D99195
+ KIC2: 01022916E945B656FDE03F806A105FA2
+ KID2: D326CB69F160333CC5BD1495D448EFD6
+ KIK2: 08037E0590DFE049D4975FFB8652F625
+ KIC3: 2B22824D0D27A3A1CEEC512B312082B4
+ KID3: F1697766925A11F4458295590137B672
+ KIK3: C7EE69B2C5A1C8E160DD36A38EB517B3
+
+Those are three keysets. The enumeration is directly equal to the KVN used.
All three keysets are 3DES keys, which
+means triple_des_cbc2 is the correct algorithm to use.
+
+.. note:: The key set configuration can be confirmed by retrieving the key
configuration using
+ `get_data key_information` from within an SCP02 session on ADF.ISD.
+
+In this example we intend to address the SIM RFM application on the `SIM`.
Which according to the manual has TAR ``B00010``
+and MSL ``0x06``. When we hold ``0x06`` = ``0b00000110`` against the SPI
coding chart (see also ETSI TS 102 225,
+section 5.1.1). We can deduct that Ciphering and Cryptographic Checksum are
mandatory.
+
+.. note:: The MSL (see also ETSI TS 102 226, section 6.1) is assigned to an
application by the `SIM` issuer. It is a
+ custom decision and may vary with different `SIM` types/profiles. In
the case of sysmoISIM-SJS1/SJA2/SJA5 the
+ counter requirement has been waived to simplify lab/research type
use. In productive environments, `SIM`
+ applications should ideally use an MSL that makes the counter
mandatory.
+
+In order to select DF.GSM (``0x7F20``) and to retrieve the select response,
two APDUs are needed. The first APDU is the
+select command ``A0A40000027F20`` and the second is the related get-response
command ``A0C0000016``. Those APDUs will be
+concatenated and are sent in a single message. The message containing the
concatenated APDUs works as a script that
+is received by the SIM RFM application and then executed. This method poses
some limitations that have to be taken into
+account when making requests like this (see also ETSI TS 102 226, section 5).
+
+With this information we may now construct a commandline for
`smpp-ota-tool.py`. We will pass the KVN as kid_idx and
+kic_idx (see also ETSI TS 102 225, Table 2, fields `KIc` and `KID`). Both
index values should refer to the same
+keyset/KVN as keysets should not be mixed. (`smpp-ota-tool` still provides
separate parameters anyway to allow testing
+with invalid keyset combinations)
+
+::
+
+ $ PYTHONPATH=./ ./contrib/smpp-ota-tool.py --kic
F09C43EE1A0391665CC9F05AF4E0BD10 --kid 01981F4A20999F62AF99988107BAF6CA
--kid_idx 1 --kic_idx 1 --algo-crypt triple_des_cbc2 --algo-auth
triple_des_cbc2 --tar B00010 --apdu A0A40000027F20 --apdu A0C0000016
+ 2026-02-26 17:13:56 INFO Connecting to localhost:2775...
+ 2026-02-26 17:13:56 INFO C-APDU sending: a0a40000027f20a0c0000016...
+ 2026-02-26 17:13:56 INFO SMS-TPDU sending:
02700000281506191515b00010da1d6cbbd0d11ce4330d844c7408340943e843f67a6d7b0674730881605fd62d...
+ 2026-02-26 17:13:56 INFO SMS-TPDU sent, waiting for response...
+ 2026-02-26 17:13:56 INFO SMS-TPDU received:
027100002c12b000107ddf58d1780f771638b3975759f4296cf5c31efc87a16a1b61921426baa16da1b5ba1a9951d59a39
+ 2026-02-26 17:13:56 INFO SMS-TPDU decoded: (Container(rpl=44, rhl=18,
tar=b'\xb0\x00\x10', cntr=b'\x00\x00\x00\x00\x00', pcntr=0,
response_status=uEnumIntegerString.new(0, 'por_ok'),
cc_rc=b'\x8f\xea\xf5.\xf4\x0e\xc2\x14',
secured_data=b'\x02\x90\x00\x00\x00\xff\xff\x7f
\x02\x00\x00\x00\x00\x00\t\xb1\x065\x04\x00\x83\x8a\x83\x8a'),
Container(number_of_commands=2, last_status_word=u'9000',
last_response_data=u'0000ffff7f2002000000000009b106350400838a838a'))
+ 2026-02-26 17:13:56 INFO R-APDU received:
0000ffff7f2002000000000009b106350400838a838a 9000
+ 0000ffff7f2002000000000009b106350400838a838a 9000
+ 2026-02-26 17:13:56 INFO Disconnecting...
+
+The result we see is the select response of DF.GSM and a status word
indicating that the last command has been
+processed normally.
+
+As we can see, this mechanism now allows us to perform small administrative
tasks remotely. We can read the contents of
+files remotely or make changes to files. Depending on the changes we make,
there may be security issues arising from
+replay attacks. With the commandline above, the communication is encrypted and
protected by a cryptographic checksum,
+so an adversary can neither read, nor alter the message. However, an adversary
could still replay an intercepted
+message and the `SIM` would happily execute the contained APDUs again.
+
+To prevent this, we may include a replay protection counter within the
message. In this case, the MSL indicates that a
+replay protection counter is not required. However, to extended the security
of our messages, we may chose to use a
+counter anyway. In the following example, we will encode a counter value of
100. We will instruct the `SIM` to make sure
+that the value we send is higher than the counter value that is currently
stored in the `SIM`.
+
+To add a replay connection counter we add the commandline arguments
`--cntr-req` to set the counter requirement and
+`--cntr` to pass the counter value.
+
+::
+
+ $ PYTHONPATH=./ ./contrib/smpp-ota-tool.py --kic
F09C43EE1A0391665CC9F05AF4E0BD10 --kid 01981F4A20999F62AF99988107BAF6CA
--kid_idx 1 --kic_idx 1 --algo-crypt triple_des_cbc2 --algo-auth
triple_des_cbc2 --tar B00010 --apdu A0A40000027F20 --apdu A0C0000016 --cntr-req
counter_must_be_higher --cntr 100
+ 2026-02-26 17:16:39 INFO Connecting to localhost:2775...
+ 2026-02-26 17:16:39 INFO C-APDU sending: a0a40000027f20a0c0000016...
+ 2026-02-26 17:16:39 INFO SMS-TPDU sending:
02700000281516191515b000103a4f599e94f2b5dcfbbda984761b7977df6514c57a580fb4844787c436d2eade...
+ 2026-02-26 17:16:39 INFO SMS-TPDU sent, waiting for response...
+ 2026-02-26 17:16:39 INFO SMS-TPDU received:
027100002c12b0001049fb0315f6c6401b553867f412cefaf9355b38271178edb342a3bc9cc7e670cdc1f45eea6ffcbb39
+ 2026-02-26 17:16:39 INFO SMS-TPDU decoded: (Container(rpl=44, rhl=18,
tar=b'\xb0\x00\x10', cntr=b'\x00\x00\x00\x00d', pcntr=0,
response_status=uEnumIntegerString.new(0, 'por_ok'),
cc_rc=b'\xa9/\xc7\xc9\x00"\xab5',
secured_data=b'\x02\x90\x00\x00\x00\xff\xff\x7f
\x02\x00\x00\x00\x00\x00\t\xb1\x065\x04\x00\x83\x8a\x83\x8a'),
Container(number_of_commands=2, last_status_word=u'9000',
last_response_data=u'0000ffff7f2002000000000009b106350400838a838a'))
+ 2026-02-26 17:16:39 INFO R-APDU received:
0000ffff7f2002000000000009b106350400838a838a 9000
+ 0000ffff7f2002000000000009b106350400838a838a 9000
+ 2026-02-26 17:16:39 INFO Disconnecting...
+
+The `SIM` has accepted the message. The message got processed and the `SIM`
has set its internal to 100. As an experiment,
+we may try to re-use the counter value:
+
+::
+
+ $ PYTHONPATH=./ ./contrib/smpp-ota-tool.py --kic
F09C43EE1A0391665CC9F05AF4E0BD10 --kid 01981F4A20999F62AF99988107BAF6CA
--kid_idx 1 --kic_idx 1 --algo-crypt triple_des_cbc2 --algo-auth
triple_des_cbc2 --tar B00010 --apdu A0A40000027F20 --apdu A0C0000016 --cntr-req
counter_must_be_higher --cntr 100
+ 2026-02-26 17:16:43 INFO Connecting to localhost:2775...
+ 2026-02-26 17:16:43 INFO C-APDU sending: a0a40000027f20a0c0000016...
+ 2026-02-26 17:16:43 INFO SMS-TPDU sending:
02700000281516191515b000103a4f599e94f2b5dcfbbda984761b7977df6514c57a580fb4844787c436d2eade...
+ 2026-02-26 17:16:43 INFO SMS-TPDU sent, waiting for response...
+ 2026-02-26 17:16:43 INFO SMS-TPDU received: 027100000b0ab0001000000000000006
+ 2026-02-26 17:16:43 INFO SMS-TPDU decoded: (Container(rpl=11, rhl=10,
tar=b'\xb0\x00\x10', cntr=b'\x00\x00\x00\x00\x00', pcntr=0,
response_status=uEnumIntegerString.new(6, 'undefined_security_error'),
cc_rc=b'', secured_data=b''), None)
+ Traceback (most recent call last):
+ File "/home/user/work/git_master/pysim/./contrib/smpp-ota-tool.py", line
238, in <module>
+ resp, sw = smpp_handler.transceive_apdu(apdu, opts.src_addr,
opts.dest_addr, opts.timeout)
+
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ File "/home/user/work/git_master/pysim/./contrib/smpp-ota-tool.py", line
162, in transceive_apdu
+ raise ValueError("Response does not contain any last_response_data, no
R-APDU received!")
+ ValueError: Response does not contain any last_response_data, no R-APDU
received!
+ 2026-02-26 17:16:43 INFO Disconnecting...
+
+As we can see, the `SIM` has rejected the message with an
`undefined_security_error`. The replay-protection-counter
+ensures that a message can only be sent once.
+
+.. note:: The replay-protection-counter is implemented as a 5 byte integer
value (see also ETSI TS 102 225, Table 3).
+ When the counter has reached its maximum, it will not overflow nor
can it be reset.
+
+smpp-ota-tool syntax
+~~~~~~~~~~~~~~~~~~~~
+
+.. argparse::
+ :module: contrib.smpp-ota-tool
+ :func: option_parser
+ :prog: contrib/smpp-ota-tool.py
diff --git a/docs/smpp2sim.rst b/docs/smpp2sim.rst
index cd86900..0ae64e7 100644
--- a/docs/smpp2sim.rst
+++ b/docs/smpp2sim.rst
@@ -55,3 +55,5 @@
SMSPPDownload(DeviceIdentities({'source_dev_id': 'network', 'dest_dev_id':
'uicc'}),Address({'ton_npi': 0, 'call_number': '0123456'}),SMS_TPDU({'tpdu':
'400290217ff6227052000000002d02700000281516191212b0000127fa28a5bac69d3c5e9df2c7155dfdde449c826b236215566530787b30e8be5d'}))
INFO root: ENVELOPE:
d147820283818604001032548b3b400290217ff6227052000000002d02700000281516191212b0000127fa28a5bac69d3c5e9df2c7155dfdde449c826b236215566530787b30e8be5d
INFO root: SW 9000:
027100002412b000019a551bb7c28183652de0ace6170d0e563c5e949a3ba56747fe4c1dbbef16642c
+
+.. note:: for sending OTA SMS messages :ref:`smpp-ota-tool` may be used.
--
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Gerrit-MessageType: merged
Gerrit-Project: pysim
Gerrit-Branch: master
Gerrit-Change-Id: If0d18a263f5a6dc035b90f5c5c6a942d46bbba49
Gerrit-Change-Number: 42237
Gerrit-PatchSet: 4
Gerrit-Owner: dexter <[email protected]>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: laforge <[email protected]>
