## 5 The Proposed Fortified-Edge 2.0 Framework
It then encrypts and digitally signs the resulting vectorized challenge before transmitting it to Client_1. Upon receiving the message, Client_1 decrypts it, verifies the signature, and forwards the challenge vector to its local ML model, which reconstructs the original n-bit binary challenge. This reconstructed challenge is applied to the PUF module, producing an n-bit binary response. The ML model in Client_1 then extracts the feature vector from this response. The vectorized response is subsequently encrypted, signed, and sent back to Client_2. Upon receiving the message, Client_2 decrypts and verifies it and sends the response vector to its ML model, which reconstructs the binary response. This response is then compared with the expected response from the stored CRP dataset. If the response is verified successfully, an authentication result is sent to Client_1. ## 6 Experimental Results and Analysis

This research utilizes a 64-bit Arbiter PUF architecture implemented on a Xilinx BASYS3 FPGA board. A dataset comprising 100,000 entries is generated using 1000 unique challenges applied across multiple PUF instances. The machine learning model based on k-mer feature extraction is trained and evaluated on a Raspberry Pi 4 to assess performance in a resource-constrained environment. ECDSA is employed for secure communication due to its efficiency, compact signature size, and strong security guarantees. Despite having a smaller key size, ECDSA offers security comparable to that of RSA with significantly larger keys. This reduction in key length minimizes computational overhead, making ECDSA especially well-suited for edge devices. Furthermore, the compact signatures generated by

Figure 6: Feature-based authentication between PUF-enabled devices. ECDSA help reduce bandwidth consumption, making it an ideal choice for lightweight, low-latency, and secure authentication frameworks deployed in distributed systems. The algorithm is implemented in a client-server model, where the server can be interchanged with any participating client, which acts as a verifier during mutual authentication in a distributed computing environment. ### Experimental Setup

The ECDSA-based secure authentication protocol uses asymmetric keys (Public/Private), which enhances the integrity of the cryptographic system where both client and server have their unique keys and only public keys are shared. The security level and speed of operation of the ECDSA algorithm are very high, and the computational cost is moderate. Using public/private key pairs eliminates the need for sharing secret keys, and the algorithm is resistant to man-in-the-middle attacks. The implementation of the ECDSA authentication protocol using the feature vectors of the CRP data comprises three steps. 1. Feature extraction: N-K-mers are used to extract the features of both challenges and responses. The K-mers are converted to vectors using the CountVectorizer function. 2. Server: The server selects a random challenge at a given index and extracts the vectors, encrypts the challenge vector using its private key, and sends the package to the client. 3. Client: The client will decrypt the package using the server's public key and convert the vectors to their corresponding binary challenge. The client will also convert the generated response to its feature form using k-mers, convert it to vectors and encrypt the vectorized response, sign it with its private key, and send it to the server for verification. The steps used to extract the characteristics of the challenges and the response are shown in Algorithm 2. This process transforms a binary sequence into a numerical feature vector suitable for secure authentication. It begins by taking a binary sequence \(B\) of length \(m\) and a k-mer size \(k\), initializing an empty list \(K\) to store extracted k-mers. By sliding a window of size \(k\) across the sequence, it extracts overlapping substrings \(K_{i}\) from positions \(i=0\) to \(i=m-k\), appending each to the list \(K\).