ETSI TS 102 940 V1.1.1 (2012-06)

Technical Specification
Intelligent Transport Systems (ITS);
Security;
ITS communications security architecture and
security management
2 ETSI TS 102 940 V1.1.1 (2012-06)

Reference
DTS/ITS-0050014
Keywords
interoperability, ITS, management, security
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3 ETSI TS 102 940 V1.1.1 (2012-06)
Contents
Intellectual Property Rights . 4
Foreword . 4
1 Scope . 5
2 References . 5
2.1 Normative references . 5
2.2 Informative references . 5
3 Definitions and abbreviations . 6
3.1 Definitions . 6
3.2 Abbreviations . 6
4 ITS reference architecture . 6
4.1 ITS applications groups . 8
4.1.1 Summary of ITS applications . 9
4.1.1.1 Cooperative awareness . 12
4.1.1.2 Static local hazard warning . 12
4.1.1.3 Interactive local hazard warning . 13
4.1.1.4 Area hazard warning . 13
4.1.1.5 Advertised services . 14
4.1.1.6 Local high-speed unicast service . 14
4.1.1.7 Local multicast service . 15
4.1.1.8 Low-speed unicast service . 15
4.1.1.9 Distributed (networked) service . 16
4.1.1.10 Multiple Applications. 16
4.1.2 Security requirements of ITS application groups. 16
4.1.2.1 Security requirements of cooperative awareness . 16
4.1.2.1.1 Authentication and Authorization. 16
4.1.2.1.2 Confidentiality . 17
4.1.2.1.3 Privacy . 17
4.1.2.2 Security requirements of static local hazard warnings . 17
4.1.2.2.1 Authentication and Authorization. 17
4.1.2.2.2 Confidentiality and Privacy . 17
4.1.2.3 Security requirements of dynamic local hazard warnings . 17
4.1.2.3.1 Authentication and Authorization. 17
4.1.2.3.2 Confidentiality and Privacy . 17
4.1.2.4 Security requirements of area hazard warnings . 18
4.1.2.4.1 Authentication and Authorization. 18
4.1.2.4.2 Confidentiality and Privacy . 18
4.1.2.5 Security requirements of other services . 18
4.1.2.6 Security requirements of multiple applications . 18
4.1.2.6.1 Authentication and Authorization. 18
4.1.2.6.2 Confidentiality and Privacy . 18
5 ITS Security architecture . 18
5.1 ITS station security architecture . 18
5.2 Security services . 19
5.3 ITS communications security architecture . 20
5.4 ITS security reference model. 20
5.4.1 Security functional elements . 22
5.4.2 Security reference points . 23
6 ITS station security management . 24
6.1 Basic principles . 24
6.1.1 Guidelines for establishing enrolment trust requirements. 25
6.2 Trust and privacy management . 26
6.3 Access control . 27
6.4 Confidentiality . 28
History . 29
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4 ETSI TS 102 940 V1.1.1 (2012-06)
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 (http://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 System (ITS).
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5 ETSI TS 102 940 V1.1.1 (2012-06)
1 Scope
The present document specifies a security architecture for Intelligent Transport System (ITS) communications. Based
upon the security services defined in TS 102 731 [4], it identifies the functional entities required to support security in
an ITS environment and the relationships that exist between the entities themselves and the elements of the ITS
reference architecture defined in EN 302 665 [1].
The present document also identifies the roles and locations of a range of security services for the protection of
transmitted information and the management of essential security parameters. These include identifier and certificate
management, PKI processes and interfaces as well as basic policies and guidelines for trust establishment.
2 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
http://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.
2.1 Normative references
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 102 637-2: "Intelligent Transport Systems (ITS); Vehicular Communications; Basic Set
of Applications; Part 2: Specification of Cooperative Awareness Basic Service".
[3] ETSI TS 102 637-3: "Intelligent Transport Systems (ITS); Vehicular Communications; Basic Set
of Applications; Part 3: Specifications of Decentralized Environmental Notification Basic
Service".
[4] ETSI TS 102 731: "Intelligent Transport Systems (ITS); Security; Security Services and
Architecture".
[5] ETSI TS 102 941: "Intelligent Transport Systems (ITS); Security; Trust and Privacy
Management".
[6] ETSI TS 102 942: "Intelligent Transport Systems (ITS); Security; Access Control".
[7] ETSI TS 102 943: "Intelligent Transport Systems (ITS); Security; Confidentiality services".
2.2 Informative references
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 TR 102 638: "Intelligent Transport Systems (ITS); Vehicular Communications; Basic Set of
Applications; Definitions".
[i.2] ETSI TR 102 863: "Intelligent Transport Systems (ITS); Vehicular Communications; Basic Set of
Applications; Local Dynamic Map (LDM); Rationale for and guidance on standardization".
[i.3] IEEE 1609.3 2010: "Wireless Access in Vehicular Environments (WAVE) - Networking
Services".
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6 ETSI TS 102 940 V1.1.1 (2012-06)
[i.4] CEN FprCEN/TS 16439: "Electronic fee collection - Security framework".
[i.5] ETSI TS 102 890-2: "Intelligent Transport Systems (ITS); Facilities layer function; Services
announcement specification".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
authorization authority: authority that provides an ITS-S with permission to invoke ITS applications and services
canonical identifier: structured identifier that is globally unique
enrolment authority: authority that validates that an ITS-S can be trusted to function correctly
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
BSA Basic Set of Applications
CA Co-operative Awareness
CAM Co-operative Awareness Message
CN Co-operative Navigation
CS Communities Services
CSM Co-operative Speed Management
DENM Decentralized Environment Notification Message
EA Enrolment Authority
IP Internet Protocol
IPv6 Internet Protocol version 6
ITS Intelligent Transport System
ITS-S ITS Station
LBS Location Based Services
LCM Life Cycle Management
OSI Open System Interconnect
PDA Personal Data Appliance
PKI Public Key Infrastructure
RHW Road Hazard Warning
RSU Road Side Unit
TTP Trusted Third Party
WAVE Wireless Access in Vehicular Environments
WSA WAVE Service Announcement
4 ITS reference architecture
EN 302 665 [1] describes an ITS station architecture based upon 4 processing layers identified as follows:
• Access Layer;
• Networking & Transport Layer;
• Facilities Layer; and
• Applications Layer.
These horizontal layers are bounded on each side by a vertical Management layer and a Security layer (Figure 1).
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7 ETSI TS 102 940 V1.1.1 (2012-06)

Figure 1: ITS station architecture (from EN 302 665 [1])
The layers in this architecture do not represent directly the Open System Interconnect (OSI) protocol modelling layers
but the functionality expected in each can be mapped to OSI model quite simply (Figure 2).

Figure 2: Mapping of OSI modelling layers to the ITS architectural layers
Having mapped the OSI protocol layers to the ITS station architecture, this can be extended into an ITS
communications architecture in which the protocol layers communicate on a peer-to-peer basis as shown in Figure 3.
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8 ETSI TS 102 940 V1.1.1 (2012-06)

Figure 3: ITS communications architecture
4.1 ITS applications groups
TR 102 638 [i.1] defines the basic set of ITS applications which it divides into groups according to the functionality
provided. Based on this a further analysis in TR 102 863 [i.2] takes into account some additional sources. The resulting
list of functional groupings from this analysis is shown in Table 1. A more detailed description can be found in
TR 102 863 [i.2], clause A.1.
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9 ETSI TS 102 940 V1.1.1 (2012-06)
Table 1: ITS application classes
Applications Class Application Use case
Active road safety Driving assistance - Co-operative awareness (CA) Emergency vehicle warning
Slow vehicle indication
Across traffic turn collision risk warning
Merging Traffic Turn Collision Risk
Warning
Co-operative merging assistance
Intersection collision warning
Co-operative forward collision warning
Lane Change Manoeuvre
Driving assistance - Road Hazard Warning (RHW) Emergency electronic brake lights
Wrong way driving warning
(infrastructure based)
Stationary vehicle - accident
Stationary vehicle - vehicle problem
Traffic condition warning
Signal violation warning
Roadwork warning
Decentralized floating car data -
Hazardous location
Decentralized floating car data -
Precipitations
Decentralized floating car data - Road
adhesion
Decentralized floating car data -
Visibility
Decentralized floating car data - Wind
Vulnerable road user Warning
Pre-crash sensing warning
Co-operative glare reduction
Cooperative traffic Co-operative speed management (CSM) Regulatory / contextual speed limits
efficiency notification
Curve Warning
Traffic light optimal speed advisory
Co-operative navigation (CN) Traffic information and recommended
itinerary
Public transport information
In-vehicle signage
Co-operative local Location based services (LBS) Point of Interest notification
services
Automatic access control and parking
management
ITS local electronic commerce
Media downloading
Global internet Communities services (CS) Insurance and financial services
services
Fleet management
Loading zone management
Theft related services/After theft vehicle
recovery
ITS station life cycle management (LCM) Vehicle software / data provisioning and
update
Vehicle and RSU data calibration
Transport related electronic financial
transactions [i.4]
4.1.1 Summary of ITS applications
In order to define security classes the communication patterns of the different applications also need to be considered.
Table 2 summarizes the communication behaviour of each application.
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Table 2: ITS applications communication behaviour
Use case Addressing Hops Frequency Direction Session
Emergency vehicle warning Broadcast Single High V2V/V2I No
Slow vehicle indication Broadcast Single High V2V No
Across traffic turn collision risk warning Broadcast Single High V2V No
Merging Traffic Turn Collision Risk Warning Broadcast Single High V2V/I2V No
Co-operative merging assistance Broadcast Single High V2V/I2V No
Intersection collision warning Broadcast Single High V2V/I2V No
Co-operative forward collision warning Broadcast Single High V2V No
Lane Change Manoeuvre Broadcast Single High V2V No
Emergency electronic brake lights Broadcast Multi Low V2V No
Wrong way driving warning (infrastructure based) Broadcast Single Low I2V No
Stationary vehicle - accident Broadcast Multi Low V2V/V2I No
Stationary vehicle - vehicle problem Broadcast Multi Low V2V/V2I No
Traffic condition warning Broadcast Multi Low V2V/I2V No
Signal violation warning Broadcast Single High I2V No
Roadwork warning Broadcast Multi Low I2V No
Decentralized floating car data - Hazardous location Broadcast Multi Low V2V/I2V No
Decentralized floating car data - Precipitations Broadcast Multi Low V2V No
Decentralized floating car data - Road adhesion Broadcast Multi Low V2V No
Decentralized floating car data - Visibility Broadcast Multi Low V2V No
Decentralized floating car data - Wind Broadcast Multi Low V2V No
Vulnerable road user Warning Broadcast Single Low V2V/I2V No
Pre-crash sensing warning Indication Broadcast Single High V2V No
Data exchange Unicast Single High V2V Yes
Co-operative glare reduction Broadcast Single Low V2V/I2V No
Regulatory/contextual speed limits notification Broadcast Single Low I2V No
Curve Warning Broadcast Single Medium I2V No
Traffic light optimal speed advisory Broadcast Multi Medium I2V No
Traffic information and Advertisement Broadcast Single Low I2V Yes
recommended itinerary Service Unicast/Multicast Multi Medium I2V No
Advertisement Broadcast Single Low I2V No
Public transport information
Service Multicast Multi Medium I2V Yes
In-vehicle signage Broadcast Single Medium I2V No
Advertisement Broadcast Single Low I2V No
Point of Interest notification
Service Multicast Single Low I2V Yes
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Use case Addressing Hops Frequency Direction Session
Automatic access control and Advertisement Broadcast Single Low I2V No
parking management
Service Unicast Single Low I2V/V2I Yes
ITS local electronic commerce Unicast Single Low I2V/V2I Yes
Media downloading Unicast Single Low I2V/V2I Yes
Insurance and financial services Unicast Single Low I2V/V2I Yes
Fleet management Unicast Single Low I2V/V2I Yes
Loading zone management Unicast/Multicast Single Low I2V/V2I Yes
Theft related services/After theft vehicle recovery Unicast Multi Low I2V/V2I Yes
Vehicle software/data provisioning and update Unicast Single Low I2V/V2I Yes
Vehicle and RSU data calibration. Unicast Single Low I2V/V2I Yes
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The information in Table 2 makes it possible to define a number of ITS application categories, thus:
• cooperative awareness;
• static local hazard warnings;
• interactive local hazard warnings;
• area hazard warnings;
• advertised services;
• local high-speed unicast services;
• local multicast services;
• low-speed unicast services; and
• distributed (networked) services;
4.1.1.1 Cooperative awareness
The purpose of cooperative awareness messages is to allow ITS users to provide other users with information regarding
their status and environment in order to improve road safety. They can be categorized as follows:
• broadcast;
• single-hop;
• time-critical;
• having low data content;
• transmitted frequently;
• vehicle-to-vehicle;
• requiring no established communications session; and
• single message with no explicit coordination.
EXAMPLES: Emergency vehicle warning
Slow vehicle indication
Across traffic turn collision risk warning
Merging traffic turn collision risk warning
Co-operative merging assistance
Intersection collision warning
Co-operative forward collision warning
Lane change manoeuvre
4.1.1.2 Static local hazard warning
Static local hazard warning messages are broadcast by fixed roadside ITS stations usually to provide continuous
information regarding a specific static condition which is relevant to road users. They can be categorized as follows:
• broadcast only from a roadside ITS-S;
• single-hop;
• time-critical;
• having low data content;
• transmitted frequently;
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• requiring no established communications session; and
• single message with no explicit coordination.
EXAMPLES: Merging traffic turn collision risk warning (if infrastructure-based)
Merging assistance (if infrastructure-based)
Intersection collision warning (if infrastructure-based)
Wrong way driving warning
Signal violation warning
Static local hazard warnings differ from cooperative awareness messages only in that they are transmitted by roadside
ITS stations rather than vehicle-based stations. Consequently, they have different requirements for privacy preservation
although all other security requirements are identical.
4.1.1.3 Interactive local hazard warning
Interactive local hazard warning messages are broadcast followed by a unicast session to provide direct cooperation in
specific hazardous situations. The basic model for these applications is that station A receives a cooperative awareness
message from station B and then returns a message to station B requesting that it takes a particular action. Based on this
there may be additional data exchanges. These exchanges may contain more personal information than is included in
cooperative awareness messages. They can be categorized as follows:
• broadcast followed by unicast;
• single-hop;
• time-critical;
• having low data content;
• transmitted frequently, but only if hazard exists;
• establish unicast communication session; and
• single message followed by coordinated session.
EXAMPLE: Pre-crash sensing warning
4.1.1.4 Area hazard warning
Area hazard warning messages are broadcast and then forwarded by the receiving stations to form a geocast. They are
sent event-driven to inform about a specific event or a specific condition to improve road safety. They can be
categorized as follows:
• broadcast;
• multi-hop with geocasting;
• time-critical;
• low data content;
• transmitted frequently, but only when hazard exists;
• requires no established communication session.
EXAMPLES: Emergency electronic brake lights
Stationary vehicle - accident
Stationary vehicle - vehicle problem
Traffic condition warning,
Roadwork warning,
Decentralized floating car data – hazardous location, precipitations, road adhesion, visibility, wind
This category is also known as Decentralized Environmental Notification Messages (DENM) within ETSI.
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14 ETSI TS 102 940 V1.1.1 (2012-06)
Area hazard warnings are not sent regularly but only when a special situation or event occurred and are not always
linked to a specific ITS-S as a point of origin. Thus, they cannot usually be used for tracking. Security mechanisms need
to take into account the forwarding of the messages.
4.1.1.5 Advertised services
Advertised services refer to services where a provider unit sends out a message of a particular type advertising that the
service is being offered and an ITS-S with the corresponding user application connects to the service. This description is
based on WAVE Service Announcements (WSAs) as described in IEEE 1609.3 [i.3] (IEEE Vehicular Technology
Society 2010a) but does not preclude any alternative method of providing Service Announcements including ETSI
Facilities service announcement TS 102 890-2 [i.5].
Advertisements are not application messag
...