Internet DRAFT - draft-qi-ipwave-vehicle-security
draft-qi-ipwave-vehicle-security
IPwave Working Group Minpeng Qi
Internet-Draft China Mobile
Intended Status: Informational
Expires: September 10, 2017 March 10, 2017
Security Problem statement for IP Wireless Access in Vehicular Environments
draft-qi-ipwave-vehicle-security-00
Abstract
This document specifies security problem about IP wireless access in
vehicular environment.It also raise requirements for IPwave as
guideline for further security solutions design. At last, using typical
IPsec/TLS solution in IPwave are evaluated.
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3 Message Protection Consideration . . . . . . . . . . . . . . . 3
4 Identity Protection Consideration . . . . . . . . . . . . . . . 4
5 Current solution analysis . . . . . . . . . . . . . . . . . . . 4
5.1 IPsec/TLS with Pre-shared key . . . . . . . . . . . . . . . . 4
5.2 IPsec/TLS with certificate . . . . . . . . . . . . . . . . . 5
6 Security Consideration . . . . . . . . . . . . . . . . . . . . 6
7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
8 References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1 Normative References . . . . . . . . . . . . . . . . . . . . 6
8.2 Informative References . . . . . . . . . . . . . . . . . . . 6
Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1 Introduction
Under IPwave scenario, a vehicle node usually connects other nodes by
using an IP address. The other node could be another vehicle, or a
server/infrastructure node with IP address. In this case, communication
data could be eavesdropped, modified or forged by the attacker as same
as attacks happened in other IP connection. Therefore, IPwave
communication must be protected. The protection must consider
confidentiality and integrity for unicast and multicast.
The protection also need to provide authenticity and privacy for
IPwave communication.
2 Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3 Message Protection Consideration
When a vehicle communicates with another vehicle or RSU. An attacker
can sniff the communication nearby. If there is no confidential
protection. The attacker could get all information. Although vihecles
are usually moving, attacker who want to collect information from
specific vehicle can drive a car and follow the target. If attacker
want to get general information rather than from specific vehicle, he
can sniff nearby an RSU. As a result, information from all vehicles
passing by are leaked. So confidentiality should be considered if
vehicle wants to send information to a specific target through unicast,
or to a specific range targets through multicast.
In another hand, an attacker could send out fake message or modified
message received from other vehicles/RSUs. So integrity should also be
considered.
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4 Identity Protection Consideration
Privacy is critical for IPwave. Since vehicles are outside, an attacker
can get vehicle's ID and its physical location. By binding ID and location
together, attacker can get more privacy information about the vehicle. For
example, track of vehicle could be leaked with its movements. What is more,
driver's behavior could be determined. It is a severe violation to the
vehicle privacy.
Binding on ID and location could be made through two ways. One way is
catching vehicle identity based on specific location(s). Here is an
example. Attacker set monitor somewhere, he can bind one vehicle's ID
and location together when there is only such vehicle there. Another way
is catching vehicle location information based on its identity. For
example, an attacker could collect one vehicle's GPS information based
on its IP address to get the track.
As the location is very important to be used for vehicle related service.
It is harder to hide location in communication, esp. for nearfield
sniffing. So the best way to keep privacy is disconnecting the relation
between identity and location. That request identity hidden or updating
frequently.
However, vehicle's id could not be hidden completely. If vehicle could not
be identified by anyone. It can only receive messages but not sending
anything out. Vehicles can't use the anonymous way to communicate with the
peer. Otherwise, the attacker can also use anonymous way to initiate
active attacks, such as sending false messages, etc.
So there is only one way left: changing vehicle's identity frequently.
However, there are several kinds of attributes which could be used to
identify vehicle, such as hardware MAC address, vehicle's IP address,
common name in vehicle's certificates, etc. All these attributes should
be changed, and should be changed syncronized. If not, a new IP address
could be connected to a common name which the certificate is not updated.
Then attacker is able to trace the vehicle through its new IP address.
5 Current solution analysis
There are solutions which could provide data confidentiality and integrity
protection with authentication. They are IPsec[RFC 4301] in IP layer and
TLS[I-D.ietf-tls-tls13] in transport layer. pre-shared key based and
certificate based solutions will be discussed separately.
5.1 IPsec/TLS with Pre-shared key
When a pre-shared key is used in IPsec/TLS tunnel establishment, it
implies that there are agreements between nodes in order to configure
same key before connection. However, in the case of V2I/V2V, at least
one node is vehicular node, which means that it probably has no
agreement with the other peer, and result in no pre-shared key could
be applied.
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5.2 IPsec/TLS with certificate
When using certificate in IPsec/TLS establishment, each node who need
to be authenticated should own a certificate. In IPwave, if the node
with certificate is vehicle type, it means that certificate ID could be
used to identify such vehicle.
In order to avoid such privacy leakage, vehicle node should not use one
certificate in a long time.
So if certificates are used in IPsec/TLS establishment, the certificates
should be updated frequently. The update timer should be carefully
designed.
If the time is too long, not only certificate ID but also the private key
would be leaked. The compromised certificate should be revoked. As a
result, revocation solution like OCSP[RFC6960] should be used. If the
vehicle node uses OCSP to verify peer's certificate, it needs to
communicate with CA. This brings additional communication round-trip
and disadvantage for high-speed vehicle connection.
If the time is too short, for example 5 minutes, it also brings problem.
CA should update certificate frequently under such assumption. It is
almost equivalent to keep connection between vehicle node and CA, which
will raise burdens to the node and CA. It can't be implemented.
Furthermore, when vehicle node travels in some areas with no Internet
connection, the vehicle node cannot update its certificate in time,
which leads to the certificate expiration. A possible solution is
letting CA issue certificates with different expiration time to
vehicle node. However, CA needs to issue a large number of certificates
one-time, as well as vehicle node needs to store a large number of
certificates also. For example, if CA needs to issue certificates for
one year and let them expired in every 5 minutes, the number will be
increased more than 100,000. And vehicle node need to store more than
100,000 certificate also. It is not acceptable for real system. Another
problem is, such certificates should be used one-by-one strictly, or it
would lead unavailable usage for a part of certificates. What is more,
although the expiration time between certificates is short, expiration
time of some certificates could be long, like the certificate with
longest validity time is 1 year rather than 5 minutes. It also faces
leakage problem.
In a word, using traditional certificate for IPsec/TLS in IPwave has
some problems. Some mechanism about certificate similar with IEEE
1609.2 should be involved.
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6 Security Consideration
This documents are specifies security issues.
7 Acknowledgements
8 References
8.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301,
DOI 10.17487/RFC4301, December 2005,
<http://www.rfc-editor.org/info/rfc4301>.
[I-D.ietf-tls-tls13] Rescorla, E., "The Transport Layer Security
(TLS) Protocol Version 1.3",
draft-ietf-tls-tls13-19(work in progress),
March, 2017
[RFC6960] Santesson, S., Myers, M., Ankney, R., Malpani, A.,
Galperin, S., and C. Adams, "X.509 Internet Public Key
Infrastructure Online Certificate Status Protocol - OCSP",
RFC 6960, DOI 10.17487/RFC6960, June 2013,
<http://www.rfc-editor.org/info/rfc6960>.
8.2 Informative References
[IEEE1609.2] "1609.2-2016 - IEEE Standard for Wireless Access in
Vehicular Environments--Security Services for
Applications and Management Messages". <https://
standards.ieee.org/findstds/standard/1609.2-2016.html>
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Author's Addresses
Minpeng Qi
China Mobile
32 Xuanwumenxi Ave,Xicheng District
Beijing 100053
China
Email: loopypuzzle@hotmail.com
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