## 5 The Proposed Fortified-Edge 2.0 Framework
In the server-side evaluation, the server waits for a client request after opening the connection. The server then selects a binary challenge from the dataset and converts it into its corresponding vectorized representation. This vectorized challenge is securely transmitted to the client. After receiving the client's vectorized response, the server reconstructs the original binary response sequence. It performs authentication by verifying whether the reconstructed response matches the expected response associated with the challenge. If there is a match, the server sends the successful authentication message to the client. Figure 11: Distribution of response vectors. Figure 10: Distribution of challenge vectors. Similarly, on the client side, the client sends an authentication request to the server and receives a vectorized challenge in the encrypted form. The client will decrypt the payload, extract the vectorized challenge, and reconstruct the original binary sequence. The binary challenge is then applied to the PUF device, and a binary response is obtained. The binary response is vectorized, encrypted, and sent to the server for verification. The client will wait for the authentication results. If the authentication fails, the connection between the client and server is closed. During each round of server-client authentication, the performance metrics are recorded. For real-time applications in resource-constrained environments, it is important to prove that there is lower computation time and lower bandwidth consumption. The performance metrics of the current protocol are shown in Table 4.

The bandwidth of the authentication process is computed as follows: The total data transferred is the sum of the challenge data size in bytes and response data size in bytes, that is, 662 bytes and 626 bytes, converted to bits by multiplying by 8. The total execution time is the total time taken by the server to authenticate the client, which is 0.028031 s.

\[\text{Bandwidth}=\frac{\text{Total Data Transferred}\times 8}{\text{Total Execution Time}} \tag{2}\]

\[r=\frac{\text{cov}(X,Y)}{\sigma_{X}\sigma_{Y}} \tag{1}\]0

The total bandwidth of the authentication process is estimated as close to 368 Kbps. The total authentication time taken is an average of 0.02 s, and the bandwidth consumed for the feature-based authentication protocol is 368 kbps, as shown from the evaluation using Equations (2) and (3). \[r=\frac{\text{cov}(X,Y)}{\sigma_{X}\sigma_{Y}} \tag{1}\]1 Server-side authentication results. \[r=\frac{\text{cov}(X,Y)}{\sigma_{X}\sigma_{Y}} \tag{1}\]2 Client-side authentication results. ### Security Analysis

The proposed feature-based authentication framework addresses critical security challenges inherent to integrated systems employing PUF. By leveraging k-mer-based feature extraction and ECDSA for secure message authentication, the current implementation is designed to be resilient against a range of prominent theoretical threats, as outlined below:

* Replay attacks: The proposed framework resists replay attacks by incorporating fresh PUF challenges for each authentication. Since challenges are randomly selected and signed by the server, reusing previous response vectors will fail signature verification or mismatch the expected response, thereby preventing unauthorized reuse. * Modeling Attacks: A machine learning attack aims to build predictive models of a PUF's behavior using observed CRP data. The proposed system prevents this by never transmitting the raw CRPs. Instead, it transmits vectorized abstractions of the challenge and response, which are obfuscated and lack direct correlation to the binary input-output, significantly reducing the feasibility of modeling attacks. * Man-in-the-Middle (MitM) Attacks: All the transmitted data, including the vectorized challenge and response, is digitally signed using ECDSA. Any tampering or substitution by an adversary in transit will result in signature verification failure at the receiver, thereby preventing MitM attacks.