## 4 Prevention Mechanisms of the Proposed Scheme
### Fog Server (FS) Further Authentication Process in the Elliptical Segment Area  
The models encompass PSAM and PESATRM. These models utilize FS and RSU for further authentication processes. This is in order to ensure safe arrival of NODVs that travel in the same ESA. The authentication process involves two-fold performances. In the first performance, V2V communications are authenticated with every other NODV. In addition, they also share the common Gk securely. Based upon this, each NODV is capable of securely acquiring the Gk by FS and the RSU. The authentication (AKDE) and secure SRSIE of NODV ensures that all vehicles that fall in the same ESATR have achieved further trustworthiness protection in the network. Based upon the PESATRM model, we also assume that the use of Vehicular RSA (VRSA) public key deployment is important. This include utilizing the common Gk as each NODV public key. Each NODV vehicle or node is also required to pass a VRSA authentication process check (this was formally achieved previously through the PSAM). The following further authentication preventive mechanism, which also utilizes the Gk, is formally deployed in the FS and the RSU authentication process, as follows. This also utilizes the following assumptions that are important for the FS and RSU further authentication process of the PESARTM integration with PSAM models, as follows:  
* FS and RSU message authentication denotes VANET safety message announcement as standardized. * PSAM integration with the PESATRM utilizes the FS parameters, which include \(G_{k}\), \(C\), and \(T\), where \(G_{k}\) is the global public key of the sender vehicle or NODV, \(C\) is \(Certx_{Nn}\) (\(n\) denotes possible pseudonyms of vehicles of entity \(X\), whereby one is also a pseudonym of NODV and others are collected pseudonyms of other NVs), and \(T\) denotes the authentication tag, which includes the integration of PSAM and PESATRM, which is installed through RSU and the FS. * Based upon each possible signer vehicle that occurs in the PESATRM, a validation \(\sigma_{X}\) is important. Here, \(\sigma_{X}\) denotes the PESATRM signature (PESATRMS) created by vehicle entity \(X\). When a vehicle entity \(Y\) is authenticated by a symmetric encryption with key \(G_{k}=K\), it is written as: \[E_{Gk}(Y)\] The FS and RSU further authentication algorithm is given as Algorithm 6. ```
1 if Neighbour vehicle \(A\) (NVA) sends authenticated safety message (ASM) and shares \(Gk\) through an initial broadcast/multicast and finally unicast to all vehicles within same ESATR, based upon the advocated scheme then
2 Assume neighbour Vehicle \(B\) (NVB) is in the same ESATR that also represents the next single hop vehicle (NSHV), which also utilizes this application and receives the ASM from \(NVA\) &
3 if\(NVB=\) NSHV then
4 generates a random key \(K\) and computes the proposed PSAM and the PESATRM parameters \(G_{k}\), \(C\), \(T\);
5 creates the PESATRMS \(\sigma_{NVB}\) over the calculated PSAM and PESATRM parameters through its current application-specific pseudonym, including \(n-1\) collected pseudonym, then
6 Set \(NVB\) to encrypt PESATRMS with the chosen key K then
7 send resulting ciphertext through the PSAM and PESATRM parameters;
8 if\(NVB\to NVB\): \(G_{k}\), \(C\), \(T\)then
9 set \(E_{Gk}(Cert_{NVB}\),..., \(Cert_{NVBn}\),\(x_{NVB}\),..., \(x_{NVBn}\),\(\sigma_{NVA}\))
10
11 If\(NVA\)\(\rightarrow\) NVB then
12 set \(E_{Gk}(Cert_{NVA}\),..., \(Cert_{NVAn}\),\(x_{NVA}\),..., \(x_{NVAn}\),\(\sigma_{NVB}\))
13 end if
14 end if
15
16 end if
```  
**Algorithm 6** Fog Server Further Authentication Algorithms for Proposed Models. In the second performance, further FS and RSU authentication processes are employed. Each V2V communication process utilizes and transmits IEEE 802.11p beacons for SRSIE. This takes place so that each NODV can also share and utilize SRSIE amongst themselves. This performance process employ probability analysis, including encryption/AKDE of each NV communication, followed by successful data exchange in the ESATR.