Dear Sameer Kumthekar, I suggest you clarify some points in your question. First of all, MD5 and SHA256 are two different hashing functions. By saying that MD5 adopts SHA256 does not mean anything. A generic hashing function, namely H, accepts typically in input a string of an arbitrary length and provides in output a string of a fixed length.

Assuming that this concept is clear, the authentication of a vehicle towards a generic entity (i.e. another vehicle, an authority, a Road Side Unit) should be done by creating an authentication protocol.

• Hash functions: https://en.wikipedia.org/wiki/Hash_function
• As the first example, please try to think of the most straightforward case scenario where two entities shared a secret (i.e. a symmetric key).
• Define better the scenario. For example, I want to authenticate a vehicle towards another vehicle or authenticate a vehicle towards an RSU, or I want to authenticate a vehicle to everything, but you need to be more specific.
• Take a look at these slides: https://www.cs.sjsu.edu/~austin/cs166-spring17/slides/CS166-Day16-SimpleAuthProtocols.pdf
• Take a look at the papers and surveys on the VANET authentication protocols.

Dear Pietro,

I am extremely sorry for the confusion caused. Yes you are right md5 & hash256 are different. I am using Hash functions for authentication. I referred md5 protocol earlier and was in that in my mind when i raised query.

Thanks a lot for reply. I will refer the links and will get back to you if needed.

BR

Sameer

Dear Sameer Kumthekar

I recommend that you test the authentication scheme with the AVISPA tool for security analysis.

Next, you need to calculate your costs, do you want an authentication scheme with a low computational cost?

You should use hash functions that have a shorter key length.

Best regards

Dear Yasher,

Yes I will be using Hash functions. Thank you for the support !

BR

Thanks Yashar ! WIll take a look !