Table 2. Preventive measures for existing Attacks

Authors	Title	Techniques /technology Used	Attacks Covered/ Security dimensions	Limitations of used technology
AkhileshSingh, et al.[25] (2016)	VANET security: Issues, challenges and solutions	Symmetric cryptography, digital signature, hash function, elliptical curve parameter and ID registration technique.	Replay attack, DOS, Routing attack, fake information attacks.
Arturo Ribagorda, et al.[26] (2010)	Overview of security issues in vehicular ad-hoc networks	Vehicular public key infrastructure, certificate validation, encryption, plausibility check mechanisms.	Eavesdropping, Identity revealing, Location tracking, attribute- based DOS attack	These techniques hadn’t addressed the issues on privacy problems due to radio frequency finger-printing
Shiang-Feng Tzeng, et al. [27] (2015)	Enhancing Security and Privacy for Identity-based Batch Verification Scheme in VANET.	System initialization, anonymous identity generation, message signing, and message verification.	Forgery attack	Effective solution for forgery attacks only. No solution for other attacks.
Ahmed Shoeb Al Hasan, et Al .[28] (2016).	Security threats in vehicular ad hoc networks.	Public Key, Symmetric and Hybrid, Certificate Revocation , ID-based Cryptography.	Privacy and security	Good privacy schemes with reduced overhead but no solution for attacks.
Lu Chen, et al. [29] (2013)	Analysis of VANET Security based on Routing protocol Information.	Elliptic curve algorithm, digital signature technology, Intrusion Detection.	Integrity, reliability and confidentiality.
Asif Ali Wagan, et al. [30] (2015)	Emerging attacks on VANET security based on GPS Time Spoofing	Prevention of Time Stamp Jumps, short lived pseudonym certificates and retrospective attack detection via logging.	Denial of service attacks, sybil attack	No solution for other attacks.
Ghassan Samara, et al.[31] (2010)	Security Analysis of Vehicular Ad-Hoc Network (VANETs)	Vehicular Public Key Infrastructure, group signature, Certificate Authority, ECC,	DOS attack, Fabrication attack, alteration attack, replay attack, message
Ram Shringar Raw, et al. [33] (2013)	Security challenges, Issues and their solutions on VANETs	ARAN, SEAD, SMT (Secure Message Transmission), NDM (Non-Disclosure Method), ARIADNE	Replay Attack, Impersonation, False Warning, information disclosure, DOS, routing attack	Efficient privacy solution but no solution for confidentiality.