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An ad-hoc is a wireless network which is used for connecting mobiles nodes. Mobiles nodes can directly connect with each other without any access points. Each node or host system in Ad-hoc network is equipped with a transmitter and receiver. In this network nodes rely on each other to establish communication, therefore each node or host system act as router. With help of Ad Hoc network we can build intelligent transport system (ITS). Information processing application system and road condition information transferring system are two big function modules in intelligent transport system (ITS). Intelligent transport system works in VANET (Vehicular Ad-hoc Network). The main task of road condition information system is exchange information between car to car and car to roadside base station. Researchers have investigated many aspects of vehicular communication. FCC has allocated bandwidth of 75 MHz for intelligent transport system in US. Vehicular communication most widely used in huge number of vehicles. This type of communication mostly used in on board computers and positioning devices such as GPS receivers and mobiles phones which opens tremendous business opportunities in present market.
2. Existing solutions
2.1 Road Condition Information Transferring System
Intelligent transport system consists of two big function modules. Information processing application system and road condition information transferring system. Information processing application system collects real time data traffic updates from road side network. Road condition Information transferring system transfers real time data traffic updates to information service center by using latest technology worldwide interoperability for Micro wave Access in internet protocol version 6. Collected data traffic updates will process logically in information center. Road Condition information transferring system transfers data between information car to car, car to road and car to access point. This system uses Ad-hoc network, so we call this type of network called vehicular Ad-hoc network. Road condition information transferring system consists of three modules Vehicles, Roadside Base station and Ad hoc Network.
Vehicles install with ultra wide band correctly reflects real time roads conditions and traffic flow by using IEEE11p Protocol. Road side base station collection the real time road condition information and transfer data to vehicles by using dedicated short range communication. Vehicles with sensor equipment, GPS and wireless transmitter will transfer road conditions to information center and neighbor vehicles by using WIMAX technology. This system was widely used in
2.2 Attack on Vehicular Ad-hoc network
In Vehicular Ad-hoc network every vehicles is mobile node faces few security threats. Where attacks on vehicular Ad-hoc network is classified into 3 dimensions like Insider vs Outsider, Malicious Vs. rational and Active vs Passive attack. Now we will discuss three possible attacks in detail
Insider Vs Outsider
Insider attacker is an authenticated member of their network he can communicate with all members in network with certified public key. outside attacker considered as a intruder and he attacks into network using tools and specified network protocols .
Malicious Vs Rational
This is second type of attack where malicious attacker always tries destroying the system or data, their functionality and aiming network members. This type attack can easily discovered when attacked by malicious attacker. Third type of attack is active and passive attack, were active attack generates signal or packets transferred into network to mislead network members. Passive attacker always watches wireless channels by using specific tools.
In furthers vehicular Ad-Hoc network plays major role in Traffic department in controlling vehicles traffic. VANETS are expected to deploy next few years and now in market basic functionality of VANETs available with low market penetration with existing infrastructure. There are few basic security issues like safety messaging protocol, digital signature has building block and securing routing.
Basic Safety Messaging Protocol
Basic security messaging protocol is security issue in VANETââ‚¬â„¢s. only few research papers describe protocols for safety solution discussed in this research paper. In Drsc specification we assumed that each vehicle v send periodical message with single hop every 300 MS with range od 10 seconds of travel time. Inter-message interval drops to 100ms with range of 15 meters. Were vehicles speed is less than 10 miles per hour. There are few vehicles makes their decision based on message received from other nodes and this vehicles may transmit new message to other vehicle .sometimes vehicles sends out its own warning messages
By using digital signature we can secure vehicular Ad-Hoc. In Ad-Hoc network digital signature is based on asymmetric key cryptography. This involves much more computation. Like encryption and decryption operation. Dos attacker feeds a victim with large number bogus signatures. Each node keeps certificate revocation list. Digital signature is verified with public key, this makes digital signature more scalable to large number of receiver.
In public key infrastructure each vehicle is assigned with public and private key pair. These keys are used for encryption or decryption. When message is transmitting into network PKI is used to send safety message. I some cases PKI includes private key and certification authority
From above equation V stands for sending vehicles ,M stands for messages associates with operator, T stands for time stamp of message received. Data exchanged in terms of nonce in sequence number.
Tamper ââ‚¬"Proof device
Secret information such as private keys are used for Tamper-proof devices in each vehicle. Tamper devices stores private information and this device is also responsible for signing for outgoing information.in order to protect tamper ââ‚¬" proof devices by attacker the device should have its own battery power which recharge from vehicle. Information is collected from road side base station and resynchronized with other vehicles which are in same direction.
In vehicle Ad-hoc network secure routing plays a major role which improves existing vehicular ad-hoc routing protocol such as AODV and DSR. In each mobiles node proactively signs its routing information using cryptographic authentication. In this paper we will discusses AODV and its security extension. Distance vector routing in AODV node has routing metric were each hope count is used routing metric and each node increases its hop count exactly by one hope. In distance routing vector a hop count have hash chain, were intermediate node cannot decreases its hope count.
Till now we discussed about secure routing and now we will discusses key management system.
In key management system we discuss about cryptographic key distribution, vocation and certification.
In vehicular Ad Hoc network each vehicle is identified by Electronic License plate it was issued by government to identify each and every vehicles and electronic chase plate which was issued by vehicle manufacture. Electronic license plate and electronic chase plate numbers are unique. These numbers should be Identify cryptographically. ELP and ECP are helps for police when chasing vehicles.
Anonymous key pairs are public and private keys authenticated by CA. these keys are used to preserve privacy information. But actual identification is done by EC and ELP. Mainly anonymous key pairs are mainly used to track vehicles position.
Key bootstrapping and Rekeying
Electronic licenses Plate is vehicle identification number issued by government and its also electronic equivalent to license plate. ELP installed in each and every vehicles which follows similar method by transportation authority. Anonymous keys are loaded into vehicle by vehicle manufacture. ELP accommodate with vehicle for long duration. Anomalous public and private keys can be renewed after all keys have been used and lifetime of theses keys have been expired.
Long with ELP and anonymous keys we should include other keys like Certification Authorities public keys.
Certification Authority issues key certificate in two way first one is governmental transportation authority and vehicle Manufactures. Now we will discuss each of them in detail
Governmental transportation Authorities:
Government transportation authorities in different countries register vehicles under their own authority. Main advantage of this method is that method is were certification authority will be under their own control. Electronic license plate and keys of each vehicle are certified by local authority in their own country. Vehicles in ad hoc network can easily communicate with each other even though they are registered in different places. This type of problems is usually solved by certificate chain leading. But, in case of VANETS there would be increase in large amount of message overhead .ELP issued by government transportation authority is useful during police chase. Police can easily tack vehicle. Certificate chain can easily replace with single certificate by certificate authority.
Vehicle manufacture can also issues certificates in limited number, main advantage of this method is we can reduce messages over head.. Vehicle manufacture maintains trust between all vehicles. In this method vehicle will store list of manufacture public keys which help to verify authentication with other vehicles and maintain trust. But main disadvantage of this method is non- governmental intuitions will involve in security mechanism.
Keys are certified by a certain certificate authority, certificate Cert, [PuKd] and ith
anonoymous key PuK, of vehicle.
Cert, [PuK,]= PuKi SigPrKCA[PUKi IDCA]
From above equation PrKCA is certificate authority private key and IDCA have unige vaule.
Vehicular Ad-Hoc network is latest technology for mobile host in wireless network, it transfers secure message between car to car and car to base station and it passes accurate information about road conditions to information transferring system. By using vehicular Ad-Hoc network no one can tamper or modify message when transferring data between two nodes. By attacker. Main aim of vehicular Ad-hoc network is to establish liability of drivers and at same time it should protect privacy drivers and passangers.till now there only few papers discussed about VANETS. By following few methods like securing routing and key management technics we can increase permorance of VANETS.
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