EMAP: Expedite Message Authentication Protocol for Vehicular Ad Hoc Networks
EMAP: Expedite Message Authentication protocol
For Vehicular Ad Hoc Networks
Mis: P. IRIN SAJI M.E.,
II yr ME/CSE
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
AKSHEYAA COLLEGE OF ENGINEERING5
The main aim of this project is to propose EMAP (Expedite Message Authentication
protocol) for vehicular Ad hoc Networks, which replaces the time-consuming
CRL(Certificate Revocation List) checking process by an efficient revocation
In vehicular networks, moving vehicles are enabled to communicate with each other
via inter vehicle communications as well as with road-side units (RSUs) in vicinity
via roadside-to-vehicle communications.
To ensure reliable operation of VANETs and increase the amount of authentic
information gained from the received messages, each OBU should be able to check
the revocation status of all the received certificates in a timely manner.
Most of the existing works overlooked the authentication delay resulting from
checking the CRL for each received certificate.
It introduce an expedite message authentication protocol (EMAP) which replaces
the CRL checking process by an efficient revocation checking process using a fast
and secure HMAC function and novel key sharing scheme employing probabilistic
random key distribution which allows an OBU to update its compromised keys even
if it previously missed some revocation messages.
In VANETs, the primary security requirements are identified as entity
authentication, message integrity, non-repudiation, and privacy preservation.
A well-recognized solution to secure VANETs is to deploy Public Key
Infrastructure (PKI), and to use Certificate Revocation Lists (CRLs) for managing
the revoked certificates.
In PKI, each entity in the network holds an authentic certificate, and every message
should be digitally signed before its transmission
Variety of attacks such as injecting false information
Modifying and replaying the disseminated messages can be easily launched.
A security attack on legitimate users.
The scale of VANET is very large.
A CRL, usually issued by a Trusted Authority (TA), is a list containing all the
In a PKI system, the authentication of any message is performed
checking if the sender’s certificate is included in the current CRL,
Since the CRL size is expected to be very large, the delay of checking the
revocation status of a certificate included in a received message is expected to be
Paper1: Eviction of Misbehaving and Faulty Nodes in Vehicular Networks in
the year of 2007 by M. Raya, P. Papadimitratos, I. Aad, D. Jungels, and J.-P.
Misbehaving or faulty network node to be detected and removed
Revocation using Compressed Certificate Revocation Lists (RC2RL) is used
LEAVE protocol is used
Event data recorders (EDRs), embeded in vehicle
security is a critical factor and a significant challenge to be met.
eviction is efficiently feasible and achieves a sufficient level of robustness.
There is a slight decrease in performance at very high densities
The average speed is much higher, and performance decreases slightly for very
Only consider for revocation
Delay will be occure
Paper 2:TACKing Together Efficient Authentication, Revocation, and Privacy
in VANETs-2009 By A. Studer, E. Shi, F. Bai, and A. Perrig,
It consisting of a central trusted authority and regional authorities (RAs) distributed
all over the network
the trusted authority acts as the group manager and the vehicles act as the
Efficiently prevents eavesdroppers from linking a vehicle’s different keys
Identify the valid vehicle
Less overhead for vehicle to vehicle communication
TACK not suitable for the safety applications in VANETs as the WAVE
This certificate is valid only within the coverage range of the RA
Paper 3 K.P. Laberteaux, J.J. Haas, and Y. Hu, “Security CertificateRevocation
List Distribution for VANET,” Proc. Fifth ACM int’lWorkshop VehiculAr InterNETworking, pp. 88-89, 2008.
In a VANET, a certificate authority issues keys and certificates to vehicles.
Each vehicle distributes these certificates to other VANET participants
Every vehicle must sign the certificate for security purpose
epidemic distribution of certificate revocation lists which is quick and
efficientEfficiently distribute the certificate
Certificate authority check the certificate status
Car-to-car epidemic distribution of certificate revocation lists
• Only employ the road side unit Distribution point
• Certificate Revocation List is consisting large certificate
• Their is no Timestamp
Paper 4:An Efficient Pseudonymous Authentication Scheme with
Strong Privacy Preservation for Vehicular Communications in the year
of 2010 by Yipin Sun, Student Member, IEEE, Rongxing Lu, Student
Member, IEEE, Xiaodong Lin, Member, IEEE
PASS supports Roadside Unit aided distributed certificate service
PASS allows the vehicles to update certificates on road,
It provide privacy for certificate
• Optimize revocation overhead
• Reducing certificate overhead
• Can not trace legitimate vehicle
• Can’t provide location privacy
Strategy for Location Privacy in VANETs in the year of 2012 by Rongxing
Lu, Member, IEEE, Xiaodong Lin, Member, IEEE, Tom H. Luan,Xiaohui
Liang, Student Member, IEEE, and Xue min (Sherman) Shen, Fellow, IEEE
As a prime target of Quality of Privacy (QoP) in ks (VANETs),
If the pseudonyms are changed in an improper time and location, such solution is
It present an effective pseudonym changing at social spot
Provable location privacy
• It is not possible to track the vehicle exactly
Expedite Message authentication protocol (EMAP) which replaces the
CRL checking process by an efficient revocation checking process
using a fast and secure HMAC function. EMAP is suitable not only for
VANETs but also for any network employing a PKI system.
To the best of our knowledge, this is the first solution to reduce the
authentication delay resulting from checking the CRL in VANETs.
EMAP has the lowest computation complexity compared with the CRL checking
processes employing linear and binary search algorithms.
The number of messages that can be verified using EMAP within 300 msec is
greater than that using linear and binary CRL checking by 88.7 and 48.38
The proposed EMAP in authentication reduces the end-to-end delay compared with
that using either the linear or the binary CRL checking process.
Development of VANET architecture
The Vehicular Adhoc Network model consists of Trusted Authority (TA), Roadside
Units (RSUs), On-Board Units (OBUs).
Trusted Authority, which is responsible for providing certificates and distributing
secret keys to all OBUs in the network.
Roadside Units which are fixed Units distributed all over the network.
On-Board Units, which are embedded in vehicles. OBUs can communicate either
with other OBUs through V2V communications or with RSUs through V2I
If an OBU want to communicate other OBU means it send an encrypted message
with a HMAC code using HMAC algorithm, it generate by using the sender id and
common secret key which knows all the unrevoked OBUs.
The receiver OBU also generates the HMAC code by using common secret key.
Whether the HMAC code is same means the receiver knows the sender OBU is an
authenticated OBU otherwise not process the message