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. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. 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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 Minpeng Qi Expires September 10, 2017 [Page 2] Internet-Draft Security Problem Statement for IPwave March 10, 2017 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. Minpeng Qi Expires September 10, 2017 [Page 3] Internet-Draft Security Problem Statement for IPwave March 10, 2017 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. Minpeng Qi Expires September 10, 2017 [Page 4] Internet-Draft Security Problem Statement for IPwave March 10, 2017 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. Minpeng Qi Expires September 10, 2017 [Page 5] Internet-Draft Security Problem Statement for IPwave March 10, 2017 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, . [RFC4301] Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, December 2005, . [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, . 8.2 Informative References [IEEE1609.2] "1609.2-2016 - IEEE Standard for Wireless Access in Vehicular Environments--Security Services for Applications and Management Messages". Minpeng Qi Expires September 10, 2017 [Page 6] Internet-Draft Security Problem Statement for IPwave March 10, 2017 Author's Addresses Minpeng Qi China Mobile 32 Xuanwumenxi Ave,Xicheng District Beijing 100053 China Email: loopypuzzle@hotmail.com Minpeng Qi Expires September 10, 2017 [Page 7]