# CAVVPM: Challenge-Based Authentication and Verification of Vehicle Platooning at Motorway
## 4 Security Analysis
### A MiTM Adversary  
Attackers are able to access the platoon by impersonating a genuine applicant who has requested to enter the platoon. We look at two examples of the assault to see how it works. To enter a platoon, the applicant uses his public key \(pk_{V}\) and his certificate \(cert_{V}\) to identify a known validator. This applicant tries to disingenuously join an adjacent platoon, but does not specifically seek out the validator. **Assimilation into a predetermined platoon:** The candidate should be allowed to target the platoon with (\(\mathrm{ID}_{V}\), \(\mathrm{pk}_{V}\), \(\mathrm{cert}_{V}\)) from the verifier's list. In Figure 7A, we see the stages of a MiTM assault. By sending a join request message \(\mathrm{m}_{\mathrm{C}}(1)\) to V, the candidate sets up the protocols. Request \(\mathrm{m}_{\mathrm{C}}(1)\) includes the person's private key-signed IDC and IDV. For example, the attacker may try to start parallel connections by blocking \(\mathrm{m}_{\mathrm{C}}(1)\) and inserting his personal demand for \(V\) to join. \[m_{M}(1)\gets ID_{V},ID_{M},pk_{M},\mathrm{cert}_{M},\mathrm{sig}_{\mathrm{ ss}_{M}}(\mathrm{REQ},ID_{M},ID_{V})\cdot\]  
The verifier authenticates the digital identity of \(M\) and challenges \(M\) with \(\Gamma\) after obtaining \(m_{M}(1)\). Because the opponent is not following the platoon, the only way to effectively finish the MiTM assault is for the legitimate candidate to successfully complete the physical requirements. \(\Gamma\). In response to [PERSON]'s first communication \(\mathrm{m}\mathrm{C}(1)\), the adversary may try to transmit by:  
\[m_{M}^{\prime}(1)\gets ID_{\mathrm{C}},E_{pk_{\mathrm{C}}}\left[\mathrm{ sig}_{\mathrm{ss}_{M}}(\Gamma,ID_{M},ID_{\mathrm{C}},t_{0}),\Gamma,ID_{M},ID_{ \mathrm{C}},t_{0}\right]\]  
consisting of the identical collection of physical obstacles \(\Gamma\) that \(V\) and M put in front of \(M\). Because the response is verified by \(M\) and not \(V\), \(C\) will terminate the process of joining. The adversary's MiTM attack fails at this point because [PERSON] only accepts requests verified by \(V\). **Choosing to join a random platoon:** The applicant might not even know the identity of the verifier when he seeks to join a battalion on the spur of the moment. We consider a candidate who follows [PERSON] at \(d_{\textit{rf}}\) but does not know [PERSON]'s identity. The attacker may then use a MiTM attack in which he spoofs [PERSON]'s credentials. Figure 7 depicts the processes involved in a MitM attack (b). The applicant [PERSON] sends mail requesting to join a battalion. \[m_{C}(1)\leftarrow\text{REQ},ID_{C},pk_{C},\text{cert}_{C}\]  
Figure 7: (**A**) ACC controllers Analysis. (**B**) Sinusoidal acceleration analysis. Keep in mind that the join is not aimed towards any particular verifier (Instead, the candidate may reply to a probe from neighboring verifiers, similar to the receiving of SSIDs from surrounding Wi-Fi networks; however, the final outcome is approximately the same in terms of understanding the name of \(V\)). \(M\) corrupts \(C\) (1) (e.g., by jamming) in order to prevent \(V\) from receiving it and then opens his own session with \(V\) by sending him a message. \[m_{M}(1)\gets ID_{V},ID_{M},pk_{M},\text{cert}_{M},\text{sig}_{sk_{M}}( \text{REQ},ID_{M},ID_{V})\]  
It is the verification. \(M\) receives a response from the verifier, who says  
\[m_{V}(1)\gets ID_{M},E_{pk_{M}}\Big{[}\text{sig}_{sk_{V}}(\Gamma,ID_{V}, ID_{M},t_{0}),\Gamma,ID_{V},ID_{M},t_{0}\Big{]}\]  
This puts \(\Gamma\) on the spot with \(M\). As an answer to \(m_{c}(1)\), the opponent pretends to be a validator and challenges the legitimate candidate with the identical obstacles that \(\Gamma\) used. \[m_{M}^{\prime}(1)\gets ID_{C},E_{pk_{C}}\Big{[}\text{sig}_{sk_{M}}(\Gamma, ID_{M},ID_{C},t_{0}),\Gamma,ID_{M},ID_{C},t_{0}\Big{]}\]  
Even if \(M\) does not follow \(V\) within the distance \(d_{\textit{ref}}\), the candidate performs the perturbations in \(\Gamma\) that induce \(V\) to accept \(M\).