# A Low-Overhead Message Authentication and Secure Message Dissemination Scheme for VANETs
## 3 Proposed Approach
### Proposed Method
We used the AES (Advanced Encryption Standard) to encrypt and decrypt the messages using a symmetric key. The execution time of the above operations is presented in \[SIG_{RSU}=E(H(\"Accept\",K,ts),PR_{RSU}).\]2 We used a message size of 39 bytes, as specified in the IEEE 1609.2 standard, for the encryption and the corresponding decryption operations. **Computation Overhead on \(GL\):** The \(GL\) is responsible for collecting, authenticating, and aggregating messages received from vehicles in its sub-region and forwarding them to the \(RSU\). Figure 3 shows the computation overhead incurred by a \(GL\) for decrypting and verifying the signature of messages received from the vehicles in its sub-region as well encrypting and signing those messages for sending them to the \(RSU\) for a number of messages ranging from 50 to 500. \[SIG_{RSU}=E(H(\"Accept\",K,ts),PR_{RSU}).\]3 Communication overhead comparison. ## 5 Conclusions and Discussion

In this paper, we presented a low-overhead \(RSU\)-aided message authentication and dissemination scheme. In this scheme, when the overhead for collecting, authenticating, aggregating, and disseminating messages increases for an \(RSU\), the \(RSU\) can designate some of the vehicles in its region as Group Leaders and make them share the overhead involved in authenticating, aggregating, and disseminating messages. Thus, this scheme helps the \(RSU\)s with reducing the computation and communication overhead related to collecting, authenticating, aggregating, and disseminating messages. We have also shown that our scheme is privacy-preserving and secure and resilient to various attacks. We also analyzed and compared the communication and computation overheads of our scheme with an \(RSU\)-aided approach for authentication and message dissemination. Both authors have contributed equally to all parts of the paper. All authors have read and agreed to the published version of the manuscript. This research received no external funding. The authors declare no conflict of interest. ## References

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