Secure & privacy enhancing communications schemes for VANET's
A B S T R A C T (See below for source code)
Vehicular ad hoc network (VANET) is an emerging type of networks which facilitates vehicles on roads to communicate for driving safety. The basic idea is to allow arbitrary vehicles to broadcast ad hoc messages (e.g. traffic accidents) to other vehicles. However, this raises the concern of security and privacy. Messages should be signed and verified before they are trusted while the real identity of vehicles should not be revealed, but traceable by authorized party.
Existing solutions either rely heavily on a tamper-proof hardware device, or cannot satisfy the privacy requirement and do not have an effective message verification scheme. In this paper, we provide a software-based solution which makes use of only two shared secrets to satisfy the privacy requirement (with security analysis) and gives lower message overhead and at least 45% higher successful rate than previous solutions in the message verification phase using the bloom filter and the binary search techniques (through simulation study).
We also provide the first group communication protocol to allow vehicles to authenticate and securely communicate with others in a group of known vehicles.
Overview of VANET
It is stated earlier that in VANET, the connectivity is done among vehicle to vehicle and vehicle to road side units (RSU). The Trusted Authority responsible for the network maintenance. The basic tool for communication is the short range radios that are being installed in any of the nodes. Vehicular node has the shortest transmission range. RSU’s are spread sporadically or regularly depending on the deployment of the network in any particular region. In real life RSU’s are spread sporadically. They act as an intermediary node between the Trusted Authority (TA) and Vehicular Node (VN).
In 1999, the FCC has allocated a frequency band of 5.850- 5.925 GHz in the US specifically for the purpose of vehicular networks. Similar bands exist in Japan and Europe. The emerging de facto standard for VC is the Dedicated Short Range Communications (DSRC). DSRC has a MAC Layer that is either a modified version of 802.11WLAN or the 3G protocol extended for decentralized access. Since the current 802.11 protocol is not suitable for VANET due to the high mobility and highly dynamic topology, a special version of it, called 802.11p is being developed by the IEEE. Also, the current 3G protocol is designed for centralized cellular networks, but in VANET, centralized infrastructure is not always present.
The increasing mobility of people has caused a high cost for societies as a consequence of the increasing number of traffic congestion, fatalities and injuries. Vehicular Ad-Hoc Networks (VANET’s) envisage supporting services on Intelligent Transportation Systems (ITSs), as collective monitoring of traffic, collision avoidance, vehicle navigation, control of traffic lights, and traffic congestion management by signalling to drivers.
VANET’s comprise vehicles and roadside equipment owns wireless interfaces able to communicate among them with wireless and multi-hop communication. VANET’s are prone to interference and propagation issues, as well as different types of attacks and intrusions, that can harm ITS services. These networks are characterized by high mobility nodes, rapidly changing network topology, wireless links subject to interference, fading due to multipath propagation and highly changing network topologies. The absence of central entities increases the complexity of security management operations, particularly, access control, node authentication and cryptographic key distribution, allowing the participation of misbehaving (malicious or selfish) nodes in the network and posing nontrivial challenges to security design.
Further, wireless communication is susceptible to jamming, eavesdropping and interferences making easy to damage information and service security. Our main motivation comes from the need for the intelligent systems in the coming years which enable us to have a safe and secure journey with entertainment.
History of Vehicular Communication
The original motives behind vehicular communications were safety on the road, many lives were lost and much more injuries have been incurred due to vehicle crashes A driver realizing the brake lights of the vehicle in front of him has only a few seconds to respond, and even if he has responded in time vehicle behind him could crash since they are unaware of what is going at the front. This has motivated one of the first applications for vehicular communications, namely cooperative collision warning which uses vehicle to vehicle communication.
Other safety applications soon emerged as well as applications for more efficient use of the transportation network, less congestion and faster and safer routes for drivers. Using only vehicle to vehicle communications these applications are not efficient. Therefore an infrastructure is needed in the form of the RSU. Although safety applications are important for governments to allocate frequencies for vehicular communications, no safety applications are as important for Intelligent Transportation Systems (ITS).
Besides road safety, new applications are proposed for vehicular networks, among these are Electronic Toll Collection (ETC), car to home communications, travel and tourism information distribution, multimedia and game applications just to name a few. However these applications need reliable communication equipment which is capable of achieving high data rates and stable Connectivity between the transmitter and the receiver under high mobility conditions and different surroundings.
Communication in Vehicular Ad hoc Networks
Vehicular Ad hoc Network (VANET) has been attracting more and more attentions from both academics. It is a critical component of the Intelligent Transportation Systems which aims at enhancing driving safety through inter-vehicle communications or communications with roadside infrastructure. In a typical VANET, each vehicle is assumed to have an On-Board unit (OBU) and there is road-side units (RSUs) installed along the roads. A trusted authority (TA) and may be some other application servers are installed in the backbone.
The On-Board Units (OBUs) and Road Side Units (RSUs) communicate using the Dedicated Short Range Communications (DSRCs) protocol over the wireless channel while the RSUs, TA, and the application servers communicate using a fixed network. Based on this each vehicle can periodically broadcast safety information containing its current speed, location, road condition and traffic accident information, etc. every 100-300ms. With the received information, other drivers can make an early response in case of exceptional situations. With multi-hop forwarding, the messages will be either terminated by an RSU or dropped when exceeding their lifetimes.
The RSU may also inform the traffic control centre to adjust traffic lights for avoiding possible traffic congestion. VANET also provides a platform for a group of known vehicles (e.g. police chasing a bank robber) to establish a secure communication channel (group communication).
Communication between Vehicle and RSUs
If a vehicle wants to send and sign a message to an RSU nearby the following verification process will be carried out:
There is a large scope for advancement in the field of vehicular ad hoc networks. Due to its highly dynamic nature VANET’s environment presents great challenges in designing appropriate protocols. There is a scope for future work in the following
The following links contains basepaper, documentation, sample images and UML diagrams of secure and privacy enhancing communication schemes for VANETs.