ETSI TS 102 723-8 V1.1.1 (2016-04)

Intelligent Transport Systems (ITS); OSI cross-layer topics; Part 8: Interface between security entity and network and transport layer

DTS/ITS-0050008

General Information

• Status: Published
• Publication Date: 27-Apr-2016
• Technical Committee: ITS WG5 - Security
• Current Stage: 12 - Completion
• Due Date: 18-May-2016
• Completion Date: 28-Apr-2016
• Mandate: M/453

Standards Content (Sample)

ETSI TS 102 723-8 V1.1.1 (2016-04)






TECHNICAL SPECIFICATION
Intelligent Transport Systems (ITS);
OSI cross-layer topics;
Part 8: Interface between security entity and network
and transport layer

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2 ETSI TS 102 723-8 V1.1.1 (2016-04)



Reference
DTS/ITS-0050008
Keywords
adaption, addressing, interface, ITS
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3 ETSI TS 102 723-8 V1.1.1 (2016-04)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 7
4 Architecture integration . 8
4.1 General . 8
4.1.1 Introduction. 8
4.1.2 Vertical message flow . 8
4.1.3 Horizontal control communication . 9
4.1.4 Protocol work split . 10
4.1.5 Multiple instances . 10
4.1.6 Error handling . 10
4.2 Security services . 10
5 Interfaces between the security entity and the networking and transport layers . 11
5.1 Interface services . 11
5.2 Service primitives and parameters . 12
5.2.1 SN-SIGN . 12
5.2.1.1 Description . 12
5.2.1.2 SN-SIGN.request . 12
5.2.1.3 SN-SIGN.confirm . 13
5.2.2 SN-VERIFY . 13
5.2.2.1 Description . 13
5.2.2.2 SN-VERIFY.request . 13
5.2.2.3 SN-VERIFY.confirm . 13
5.2.3 SN-ENCRYPT . 14
5.2.3.1 Description . 14
5.2.3.2 SN-ENCRYPT.request . 14
5.2.3.3 SN-ENCRYPT.confirm . 15
5.2.4 SN-DECRYPT . 15
5.2.4.1 Description . 15
5.2.4.2 SN-DECRYPT.request . 15
5.2.4.3 SN-DECRYPT.confirm . 15
5.2.5 SN-IDCHANGE-SUBSCRIBE . 15
5.2.5.1 Description . 15
5.2.5.2 SN-IDCHANGE-SUBSCRIBE.request . 16
5.2.5.3 SN-IDCHANGE-SUBSCRIBE.confirm . 16
5.2.6 SN-IDCHANGE-EVENT . 16
5.2.6.1 Description . 16
5.2.6.2 SN-IDCHANGE-EVENT.indication . 16
5.2.6.3 SN-IDCHANGE-EVENT.response . 16
5.2.7 SN-IDCHANGE-UNSUBSCRIBE . 17
5.2.7.1 Description . 17
5.2.7.2 SN-IDCHANGE-UNSUBSCRIBE.request . 17
5.2.7.3 SN-IDCHANGE-UNSUBSCRIBE.confirm . 17
5.2.8 SN-IDCHANGE-TRIGGER. 17
5.2.8.1 Description . 17
5.2.8.2 SN-IDCHANGE-TRIGGER.request . 17
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4 ETSI TS 102 723-8 V1.1.1 (2016-04)
5.2.8.3 SN-IDCHANGE-TRIGGER.confirm . 17
5.2.9 SN-ID-LOCK . 17
5.2.9.1 Description . 17
5.2.9.2 SN-ID-LOCK.request . 18
5.2.9.3 SN-ID-LOCK.confirm . 18
5.2.10 SN-ID-UNLOCK . 18
5.2.10.1 Description . 18
5.2.10.2 SN-ID-UNLOCK.request . 18
5.2.10.3 SN-ID-UNLOCK.confirm . 18
5.2.11 SN-LOG-SECURITY-EVENT. 18
5.2.11.1 Description . 18
5.2.11.2 SN-LOG-SECURITY-EVENT.request . 18
5.2.11.3 SN-LOG-SECURITY-EVENT.confirm . 21
5.2.12 SN-ENCAP . 21
5.2.12.1 Description . 21
5.2.12.2 SN-ENCAP.request . 21
5.2.12.3 SN-ENCAP.confirm. 21
5.2.13 SN-DECAP . 22
5.2.13.1 Description . 22
5.2.13.2 SN-DECAP.request . 22
5.2.13.3 SN-DECAP.confirm. 22
6 SN-SAP procedures . 23
6.1 Outbound message handling. 23
6.1.1 Using SN-SIGN and SN-ENCRYPT . 23
6.1.2 Using SN-ENCAP . 24
6.2 Inbound message handling . 24
6.2.1 Using SN-VERIFY and SN-DECRYPT . 24
6.2.2 Using SN-DECAP . 24
6.3 ID Management . 25
6.3.1 IDCHANGE Notifications . 25
6.3.1.1 Introduction . 25
6.3.1.2 Id-change event hook . 25
6.3.1.3 Two phase commit process . 25
6.3.2 Prevent IDCHANGES . 28
6.3.3 Trigger IDCHANGES . 29
6.4 Log security event . 29
Annex A (informative): SN-Command . 30
A.1 Overview . 30
A.2 Description . 30
A.2.1 SN-IDCHANGE-EVENT service: SN-COMMAND.request (see clause 5.2.6.2) . 30
A.2.2 SN-IDCHANGE-EVENT service: SN-COMMAND.confirm (see clause 5.2.6.3) . 31
Annex B (informative): SN-Request . 32
B.1 Overview . 32
B.2 Description . 32
B.2.1 SN-ENCRYPT service: SN-REQUEST.request (see clause 5.2.3.2) . 32
B.2.2 SN-ENCRYPT service: SN-REQUEST.confirm (see clause 5.2.3.3) . 33
Annex C (informative): Example of service primitives description in the framework of
ISO 24102-3 . 34
C.1 Overview . 34
C.1.1 Introduction . 34
C.1.2 Class for SN-SAP Command.request service primitive functions . 34
C.1.3 Class for SN-SAP Command.confirm service primitive functions . 34
C.1.4 Class for SN-SAP Request.request service primitive functions . 35
C.1.5 Class for SN-SAP Request.confirm service primitive functions . 35
History . 36

ETSI

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5 ETSI TS 102 723-8 V1.1.1 (2016-04)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Intelligent Transport Systems
(ITS).
The present document is part 8 of a multi-part deliverable. Full details of the entire series can be found in part 1 [i.1].
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
ITS stations are complex systems that may be implemented in different ways. The reference architecture is described in
the communications architecture standard ETSI EN 302 665 [1], clause 4.4. The present document aims to address the
security interface from a functional point of view. Access control to the Service Access Point and further definitions of
station internals are out of scope of the present document.
The SAP specification is specific to the ITS architecture but generic to the concrete technologies used.
Therefore, the present document is structured in the following way:
First, the architecture integration is outlined. Secondly, functionalities are collected from related standards and mapped
to service primitives. Finally, the use of service primitives in procedures is described.
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6 ETSI TS 102 723-8 V1.1.1 (2016-04)
1 Scope
The present document specifies interfaces between the ITS security entity and the ITS network and transport layers
including interface services and service primitives which are extensible in order to achieve general applicability.
Additionally, it specifies related procedures and common parameters.
The SN-SAP description in the present document is functional as according to the ISO model as modified by ETSI
EN 302 665 [1].
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
https://docbox.etsi.org/Reference/.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
[1] ETSI EN 302 665: "Intelligent Transport Systems (ITS); Communications Architecture".
[2] ETSI TS 102 940: "Intelligent Transport Systems (ITS); Security; ITS communications security
architecture and security management".
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI TS 102 723-1: "Intelligent Transport Systems (ITS); OSI cross-layer topics; Part 1:
Architecture and addressing schemes".
[i.2] ETSI TS 101 539-2: "Intelligent Transport System (ITS); V2X Applications; Intersection Collision
Risk Warning (ICRW) application requirements specification".
[i.3] ETSI TS 101 539-3: "Intelligent Transport Systems (ITS); V2X Applications; Part 3: Longitudinal
Collision Risk Warning (LCRW) application requirements specification".
[i.4] PRE-DRIVE C2X Deliverable D1.3: "Security Architecture".
[i.5] EVITA Deliverable D3.2: "Secure On-board Architecture Specification".
[i.6] ETSI TS 102 637-1: "Intelligent Transport Systems (ITS); Vehicular Communications; Basic Set
of Applications; Part 1: Functional Requirements".
[i.7] ETSI TS 102 637-2: "Intelligent Transport Systems (ITS);Vehicular Communications; Basic Set
of Applications; Part 2: Specification of Cooperative Awareness Basic Service".
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7 ETSI TS 102 723-8 V1.1.1 (2016-04)
[i.8] ETSI ES 202 663: "Intelligent Transport Systems (ITS); European profile standard for the physical
and medium access control layer of Intelligent Transport Systems operating in the 5 GHz
frequency band".
[i.9] ISO 24102-3: "Intelligent transport systems -- Communications access for land mobiles (CALM) -
- ITS station management -- Part 3: Service access points".
[i.10] ETSI TS 103 097: "Intelligent Transport Systems (ITS); Security; Security header and certificate
formats".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in ETSI EN 302 665 [1], ETSI
TS 102 940 [2] and the following apply:
security association: addressing information and 'security material' for connecting to the 'security management entity'
NOTE: This corresponds to 'enrolment authorities' and 'authorization authorities'.
security entity: functional entity inside an ITS station which offers 'security mechanisms'
security protocol: protocol used to encode and decode 'security material' and messages between ITS Stations
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in ETSI EN 302 665 [1], ETSI TS 102 940 [2] and
the following apply:
ASN Abstract Syntax Notation
CAM Cooperative Awareness Message
DENM Decentralized Environmental Notification Message
ICRW Intersection Collision Risk Warning
ID 'pseudonym' identity
IN-SAP access layer - networking & transport layer SAP
ISO International Organization for Standardization
ITS-S ITS-Station
LCRW Longitudinal Collision Risk Warning
NF-SAP Networking & transport layer - Facilities layer SAP
RX Receiver
SA Security Association
NOTE: SA is contextual dependent either "name of interface between security entity and ITS-S applications" as
given in ETSI EN 302 665 [1] or "Security Association".
SAP Service Access Point
SF-SAP Security entity - Facilities layer SAP
SN-SAP Security entity - Networking & transport layer SAP
TX Transmitter
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8 ETSI TS 102 723-8 V1.1.1 (2016-04)
4 Architecture integration
4.1 General
4.1.1 Introduction
Figure 1 shows the ITS station reference architecture, as defined in ETSI EN 302 665 [1]. The present document
contains the specification of the Service Access Points (SAP), connecting the security entity and the networking and
transport layers, i.e. SN-SAP.

Figure 1: ITS station reference architecture
Interaction between the security entity and the layers may follow two principles. First, the vertical message flow
through the layers from top to bottom or vice versa. Secondly, the horizontal control communication from the security
entity towards the corresponding layer. Both are described in clauses 4.1.2 and 4.1.3.
4.1.2 Vertical message flow
Figure 2 extends the ITS station reference architecture by illustrating the overall information flow through the layers,
from originating application on the left hand side, to the receiving application on the right hand side.

Figure 2: TX (left) and RX (right) information flow through the ITS station
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9 ETSI TS 102 723-8 V1.1.1 (2016-04)
The present document specifies only the SN-SAP, therefore only a subset of the ITS station reference architecture has to
be taken into account. Figure 3 shows the typical information flow between any sending (TX) and receiving (RX) party,
with regard to the SN-SAP only. The security entity acts like a layer inside the networking and transport layers, i.e. it is
called during the processing of messages traversing the networking and transport layers. The security entity will
however not act as a layer above or below the networking and transport layers. This means that interactions with
Facilities and Access layers are achieved via other means, i.e. the NF-SAP is used for the interaction between the
networking and transport layers and Facilities layers, whereas the IN-SAP is used for the interaction between the access
layer and networking and transport layers.

Figure 3: SN-SAP centric Information flow
4.1.3 Horizontal control communication
Figure 4 outlines the second communication principle. There is a horizontal control communication between the
security entity and the corresponding communications layer, networking and transport in this case. This is needed for
the ID change functionality introduced later. In general, the security entity will be able to indicate an ID change to the
corresponding layer and some additional ID change related calls.

Figure 4: Horizontal Control Communication
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4.1.4 Protocol work split
The SN-SAP provides a set of primitive security functions to the networking and transpo
...