A Computational Analysis of ECC Based Novel Authentication Scheme in VANET

ABSTRACT


INTRODUCTION
The vehicular ad hoc network (VANET) is a sub type of MANET (Mobile Adhoc Network). Moving vehicles and stationary RSU act as nodes in the network. It is rising area of research. It provides intelligent transportation management by improving safety in driving, traffic optimization, and comfort in driving to driver/owner.
Each vehicle in the network can send and receive messages by On Board Unit (OBU) and equipped with Event Data Recorder, GPS, Trusted component etc. The Roadside Units (RSU) is responsible for broadcasting safety messages periodically. Communication in VANET mainly takes place in three different ways V2V (Vehicle to Vehicle), V2I (Vehicle to infrastructure), and I2I (Infrastructure to Infrastructure). Due to an openness of VANET, outsider nodes can enter in to the network. Security is a bigger challenge in VANET [8]. A attacker node can carry different attacks to disturb the working of network. Considering these security problems, participated node in the network must be trusted by proper authentication. Because of dynamic nature of network vehicles are very less time to establish communication with each other and to RSU.
Time required for communication also affect the effectiveness of communication in VANET. This paper first addresses a proposed scheme and its variation to improve time and security of authentication, over traditional scheme like RSA. In analysis part, we implemented plain ECC in VANET and compare with our proposed scheme implementation i.e. AECC and EECC. In this paper section 1 addressed basic of VANET. Section 2 gives related work done in the Authentication of VANET. Section 3 gives proposed novel schemes. Section 4 gives computational analysis on the basis of result recorded in Vsim (VANET Simulator). Section 5 concludes the paper.
VANET scenario is as shown in Figure 1. It gives different types of communication. As shown in the figure vehicle can communicate with other vehicle via V2V communication, vehicle can communicate with infrastructure (RSU) through V2I communication, vehicle can communicate with road side infrastructure using V2R communication [1]. Vehicle to sensor communication is depicted by V2S.  Table 1 show the detailed survey of research in VANET their strength, weakness and future scope of research. Literature survey shows that over all time required for digital signature generation and verification of message in V2V communication requires more time in some schemes, which degrades performance of network. In some schemes security can hamper, If CA, RA or RSU compromise. Space required storing private keys and certificates also are an issue in some scheme. Time required for waiting, packet accessing and decision taking is also affect on performance. We found that, there is need of more research in authentication of VANET to improve authentication speed and security in VANET.

PROPOSED WORK
Observation made from previous research about ECC based authentication.

ECC Disadvantages:
a. ECC increases the size of the encrypted message significantly more than RSA encryption. b. Most ECDSA implementations require a secure random generator -if the same random value is reused (for different plaintext) then the private key parameter can simply be calculated; c. ECC is much more efficient than RSA for signature generation and decryption, but it's still much slower than symmetric algorithms; d. Type of curve and curve parameter agreement is required in ECC algorith From previous research survey, we found that, there is need of more research a. To provide faster authentication in VANET with preserving security requirements. Figure 2 shows the framework for proposed work. It shows three different authentication schemes for VANET first one is plain ECC/ Basic ECC algorithm. The second block shows Adaptive ECC algorithm, and the third block shows Enhanced ECC algorithm. Table 2 gives terms used for AECC and EECC algorithm.

ECC Based Authentication: Authentication Using Elliptic Curve Cryptography 3.3.1. Elliptic Curve Cryptographic Algorithm (ECC)
ECC is an alternative mechanism for implementing public-key cryptography. Figure 3 shows elliptic curve which is considered for ECC algorithm. The equation of an elliptic curve is given as, y2=x3 +ax +b [7]  Terms that will be used in Cryptography using ECC, E->Elliptic Curve P->Point on the curve n->Maximum limit (This should be a prime number ) Figure 3. Elliptic curve

Key Generation
It is frst stage where public and private key is generated. The message is encrypted by receiver public key and the receiver is decrypting message by its own private key. Random number'd' selected within the range of 'n'. Using the following equation Public key will be generate Q=d * P Where: d=the random number that has been selected within the range of (1 to n-1). P=the point on the curve. 'Q' is the public key and'd' is the private key.

Encryption
Let 'm' be the message which want to send. Ths message is represented on the curve. This has in-depth implementation details. Consider 'm' has the point 'M' on the curve 'E'. Randomly select 'k' from [1 -(n-1)]. Two cipher texts will be generated let it be C1 and C2. C1=k*P C2=M + k*Q C1 and C2 will be send.

Decryption:
We have to get back the message 'm' that was send to us, M=C2-d*C1 M is the original message that we have send.

AECC (Adaptive Elliptic Curve Cryptography) Based Authentication
AECC is variation in ECC. In this using an adaptive key size algorithm varying keys are generated. This algorithm uses the random key size where no attacker can guess, the key size at the current time, and fails to break it. In this key sizes are vary after every defined timeslot. When an attacker tries to guess the key to break the system, as the ECC is strong enough this does not happen easily. But when an attacker succeeds to do so, because of the adaptive key size (AKS) algorithm, the key is no longer relevant to that attacker.

EECC (Enhanced Elliptic Curve Cryptography) Based Authentication
Enhanced ECC algorithm is extended version of AECC. In this an extra parameter is added during the transmission of information from the vehicle to the RSU for key generation. These additional parameters give the information about the vehicle ID, and the location of the vehicle from the RSU, and the other vehicle. This algorithm provides replica and Sybil attack detection along with authentication.

COMPUTATIONAL ANALYSIS OF ECC & AECC
The analysis is carried out by implementing ECC and AECC in Vsim (VANET Simulator). Vsim is java based simulator for Testing, Analyzing, and implementing different protocols in VANET. We can add, create, modify scenario in simulator. Vsim provide different packages for creating VANET environment. We can load map of different cities. We can load different scenarios for same map. Figure 4 shows map of NewYork_noTS.xml is load on the VANET Simulator. Similarly we can load a map of Berlin_noTS.xml or Puebla_noTS.xml on the simulator. Or generate new map as per requirement. Figure 5 shows uploading of New York road scenario with 2500 slow and 2500 fast vehicles with 100m communication range. Road side units are within 500m radius communication range. Vehicles are shown by small black dots and gray color circle is used for RSU. Figure 6 Figure 7 shows information about vehicles on the marked path. Information contains the Name, length, Max speed, Lane/direction, start location, destination location, current speed, Travel time, Travel distance, known vehicles, known messages, failed forward messages, known penalties etc.  Figure 8 shows graphically analysis of time required for ECC and AECC for authentication with respective iteration. In case of ECC same key is used for each iteration, and for adaptive key selected from small, large or medium group of key sizes. Graph shows that as compare to ECC, AECC required less time. So AECC is faster than ECC. Figure 9 shows that number of vehicle authenticated by AECC per second are more than ECC. Table 3 shows ECC and AECC time required for authentication. Table 4 shows number of vehicle authenticated using ECC and AECC.  Security of authentication is checked by its private key breaking possibilities. Table 5 shows key breaking possibilities. Figure 10 shows that key breaking possibility of AECC is less as it takes more turn for breaking key than ECC. So AECC is more secure than ECC.  From above analysis we can list out following advantages of AECC Adaptive key size algorithm it's advantages: a. Here we using secure key selector -if the same random value is reused (for different plaintext) then the private key parameter cannot be calculated because of different key size. b. By using less key sizes we can faster the authentication speed. c. Here along with curve agreement, this algorithm also required key agreements.

CONCLUSION
Security is an important issue in VANET. Authentications prohibit entry of the unauthorized malicious user. It helps to avoid various security attacks. This paper addresses issues in authentication for improving the speed of authentication. It also takes care to maintain same or rather more security, as compared to previous authentication schemes like RSA and ECC. Here we given the computational analysis of result obtain in VANET Simulator. The time required for authentication is verified by taking multiple iteration reading, which proves that AECC required less time as compared to ECC. A number of vehicles authenticated by RSU per second are more in case of AECC than ECC; at the end security of the scheme is checked by key breaking possibility. Our needs for faster authentication reflect in improving the performance of RSU by serving more number of vehicles. In future work, we are going to add more security parameter in EECC (Enhance Elliptic Curve Cryptography) scheme. We gave an algorithm for same in this paper but an implementation is in process. Its implementation and computational analysis will be the part of our future scope.