IPwave Working Group Minpeng Qi Internet-Draft China Mobile Intended Status: Informational Expires: April 30, 2017 October 31, 2016 Security Problem statement for IP Wireless Access in Vehicular Environments draft-qi-its-v2vauth-01 Abstract This document specifies security problem about IP wireless access in vehicular environment. It also analyses the authentication part in IPsec/TLS. It proposes a new solution to make IPsec/TLS more fit for vehicular environment. 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. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Copyright and License Notice Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of Minpeng Qi Expires April 30, 2017 [Page 1]
Internet-Draft Security Problem Statement for IPwave October 31, 2016 publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 IPsec/TLS with Pre-shared key . . . . . . . . . . . . . . . . . 3 3 IPsec/TLS with certificate . . . . . . . . . . . . . . . . . . 3 4 Possible Solution . . . . . . . . . . . . . . . . . . . . . . 4 5 Security Consideration . . . . . . . . . . . . . . . . . . . . 5 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 7 References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 Minpeng Qi Expires April 30, 2017 [Page 2]
Internet-Draft Security Problem Statement for IPwave October 31, 2016 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, security channel between two nodes like IPsec/TLS are also needed in IPwave to ensure the safety of data transmission. As a result, pre-shared key or certificate are involved when IPsec/TLS tunnel are established. However, some issues are raised due to vehicular environment. This document analyzes such issue and will propose security considerations for IPwave. 1.1 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]. 2 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. 3 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. If an attacker could get the physical location of such node, its certificate ID could be used to bind with its location. So the track of vehicle could be obtained with its movements. It is a severe violation to the privacy of vehicle node. In order to avoid such privacy leakage, vehicle node should not use one certificate in a long time. A simple solution is to make vehicle node anonymous. This could be work when applying TLS between vehicle node as client and infrastructure node as a server. However, this could not be work in V2V mode or when vehicle need to send out data. Vehicle acts as data sender rather than data receiver. It should guarantee validity of the data it sends 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. Minpeng Qi Expires April 30, 2017 [Page 3]
Internet-Draft Security Problem Statement for IPwave October 31, 2016 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 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 certificate for IPsec/TLS in IPwave has some problems. 4. Possible Solution Based on the analysis, the problem using pre-shared key is caused by no previous agreements before secure tunnel established. And the problem using certificate is caused by the privacy leakage and the validity time. So a possible solution is to bind pre-shared key and certificate together. By using certificate with insecure environment to generate keys in two nodes, an IPsec/TLS secure tunnel can be established. Minpeng Qi Expires Aprial 30, 2017 [Page 4]
Internet-Draft Security Problem Statement for IPwave October 31, 2016 6 Security Consideration This documents are specifies security issues. 7 Acknowledgements 8 References Author's Addresses Minpeng Qi China Mobile 32 Xuanwumenxi Ave,Xicheng District Beijing 100053 China Email: qiminpeng@chinamobile.com Minpeng Qi Expires April 30, 2017 [Page 5]