International Journal of Engineering and Management Research

1. Introduction

1.1 Background

Unmanned Aerial Vehicles (UAVs) have emerged as an essential component of modern intelligent systems due to their flexibility, mobility, and cost-effectiveness. UAVs are extensively deployed in applications including environmental monitoring, military reconnaissance, border surveillance, disaster response, precision agriculture, smart cities, package delivery, and Internet of Things (IoT) networks [1,2]. In most of these applications, UAVs continuously exchange sensitive information with Ground Stations (GSs) through wireless communication channels, making communication security a critical requirement [1,3].

Despite their increasing adoption, UAV platforms typically possess limited computational resources, memory capacity, and battery power. These resource constraints make the implementation of computationally intensive public-key cryptographic mechanisms challenging, particularly in real-time applications requiring low latency and high energy efficiency. Consequently, lightweight authentication protocols have become an active research area for securing UAV communications while maintaining acceptable computational and communication costs [1,4,5].

1.2 Motivation

Wireless communication between UAVs and Ground Stations is inherently exposed to various security threats because transmissions occur over open and potentially hostile communication channels. An adversary operating under the Dolev-Yao threat model may intercept, modify, replay, or fabricate protocol messages, enabling attacks such as replay attacks, impersonation attacks, man-in-the-middle attacks, session hijacking, and unauthorized device access [1,2,4]. Existing lightweight authentication schemes often rely solely on pre-shared symmetric keys or static credentials, which may become vulnerable if long-term secrets are compromised [4,6,7].

Physically Unclonable Functions (PUFs) have recently emerged as a promising hardware-based security primitive capable of generating unique and unclonable device identities without permanently storing secret keys in non-volatile memory.

6. Performance analysis demonstrates that the proposed protocol achieves lower computational and communication overhead compared with existing authentication protocols while maintaining a high level of security.

1.5 Organization of the Paper

The remainder of this paper is organized as follows. Section 2 reviews related work on UAV authentication and PUF-based security mechanisms. Section 3 presents the system model, threat model, and design assumptions. Section 4 describes the proposed LightSecurePUF authentication protocol in detail. Section 5 provides the formal and informal security analysis, including Scyther-based verification. Section 6 evaluates the computational and communication performance of the proposed protocol and compares it with existing approaches. Finally, Section 7 concludes the paper and discusses future research directions.

2. Related Work

Secure authentication and key establishment have become fundamental requirements for Unmanned Aerial Vehicle (UAV) networks because wireless communication between UAVs and Ground Stations (GSs) is vulnerable to replay, impersonation, man-in-the-middle (MITM), and device capture attacks. At the same time, UAVs are constrained by limited computational capability, battery capacity, and storage resources. Consequently, recent research has focused on lightweight authentication protocols that provide strong security while minimizing computational and communication overhead [1,2].

Early lightweight authentication protocols for UAV networks primarily relied on symmetric cryptographic primitives such as hash functions, XOR operations, and message authentication codes (MACs). These schemes significantly reduced computational complexity compared with public-key cryptography; however, many depended on static credentials or long-term shared secrets. As a result, compromise of stored credentials could enable replay attacks, impersonation attacks, or session key disclosure. Moreover, several early protocols lacked formal verification or were subsequently shown to contain security weaknesses [1,2,4].

To improve security, researchers introduced Physically Unclonable Functions (PUFs) as hardware roots of trust for UAV authentication. Because PUF responses originate uncontrollable manufacturing

mechanism for both UAV-to-Ground Station and UAV-to-UAV communications using PUF technology together with lightweight hash operations. The protocol was formally analyzed using Scyther, BAN logic, and the RoR model while demonstrating improved computational efficiency [10].

Although recent studies have significantly advanced lightweight UAV authentication, several challenges remain. First, many protocols employ the PUF only as a device authentication primitive, whereas the session key is derived primarily from long-term shared secrets and random nonces [5], [6], [10]. Consequently, the PUF contributes little to the actual key establishment process. Second, some schemes introduce additional mechanisms such as fuzzy extractors, blockchain, biometric authentication, chaotic maps, or multi-factor authentication to strengthen security; however, these techniques increase implementation complexity, storage requirements, or computational overhead, making them less attractive for highly resource-constrained UAV platforms [3], [7], [8], [9].

Furthermore, although several protocols provide comprehensive formal security analysis using BAN logic, AVISPA, the Real-or-Random (RoR) model, or blockchain-based trust analysis, comparatively fewer lightweight UAV authentication schemes have been modeled using Scyther with explicit verification of secrecy, authentication, synchronization, and agreement properties in a concise three-message protocol [4], [10]. Formal symbolic verification remains valuable because it enables automated analysis against an active Dolev-Yao adversary model, in which an attacker can intercept, modify, replay, and fabricate protocol messages without breaking the underlying cryptographic primitives [11].

Table 1: Summary of Related Work

1. The Registration Authority is fully trusted and performs secure offline enrollment.
2. Each UAV possesses a unique hardware PUF that cannot be physically cloned.
3. The Ground Station securely stores the registered credentials associated with each legitimate UAV.
4. The long-term shared secret remains confidential after the registration phase.
5. Hash functions and HMAC are assumed to be cryptographically secure.
6. The communication channel between the UAV and GS is insecure and completely controlled by an adversary.

3.2 Threat Model

The security analysis of the proposed protocol follows the widely adopted Dolev-Yao [11] adversary model, which assumes that an attacker has complete control over the public communication channel.

Specifically, the adversary is capable of:

a) intercepting transmitted messages
b) modifying protocol messages
c) replaying previously captured messages
d) fabricating new protocol messages
e) deleting or delaying transmitted packets
f) initiating concurrent protocol sessions
g) impersonating legitimate communication entities whenever protocol weaknesses permit.

However, the adversary is not capable of:

a) breaking secure cryptographic hash functions
b) forging valid HMAC values without knowledge of the corresponding secret key
c) predicting fresh random nonces generated during protocol execution
d) cloning the intrinsic physical characteristics of a legitimate PUF
e) deriving the challenge-response behavior of the enrolled PUF within practical computational limits.

In addition, it is assumed that the Registration Authority and the Ground Station remain uncompromised throughout protocol execution. Although an attacker may physically capture a UAV, extracting the exact hardware characteristics of its PUF is considered computationally infeasible because the response is determined by uncontrollable manufacturing variations.

G7. Secrecy of Long-Term Credentials

The long-term shared secret K and the enrolled PUF key must remain confidential throughout protocol execution, even in the presence of an active adversary controlling the communication channel.

G8. Lightweight Computation

The protocol should avoid computationally expensive public-key operations such as modular exponentiation, elliptic curve scalar multiplication, and bilinear pairings. Instead, authentication is achieved using only lightweight hash computations, HMAC operations, and PUF evaluations, thereby minimizing computational overhead for resource-constrained UAV platforms.

G9. Formal Verifiability

The protocol should be amenable to formal verification under the symbolic Dolev-Yao model. Accordingly, the proposed protocol is modeled in the Security Protocol Description Language (SPDL) and formally verified using the Scyther protocol verification tool, demonstrating secrecy, mutual authentication, agreement, synchronization, and key confirmation properties.

4. Proposed LightSecurePUF Authentication Protocol

4.1 Overview

This section presents LightSecurePUF, a lightweight mutual authentication and session key establishment protocol designed for secure communication between a UAV and a Ground Station (GS). The protocol integrates a challenge-response Physically Unclonable Function (PUF) with lightweight cryptographic primitives, including cryptographic hash functions and HMAC, to achieve secure authentication while maintaining low computational overhead.

Unlike many existing PUF-based authentication protocols, the proposed scheme incorporates the challenge-dependent PUF response directly into the session key derivation process. Consequently, the PUF contributes not only to device authentication but also to establishing a fresh session key for every communication session.

The protocol consists of two phases:

1. Registration Phase

• 1D_UAV
• K_SHARED
• _PUFKEY

The Registration Authority is not involved during subsequent authentication sessions.

4.4 Mutual Authentication Phase

The authentication protocol consists of three lightweight message exchanges.

Authentication Completion:

The Ground Station verifies

MAC₃

If the verification succeeds,

• mutual authentication is completed;
• both parties share an identical session key;
• secure communication begins.

4.5 Session Key Establishment

Unlike conventional lightweight authentication protocols that derive the session key solely from long-term credentials and random numbers, the proposed protocol additionally incorporates the challenge-dependent PUF response.

This construction provides several security advantages:

Figure 2: Proposed LightSecurePUF Authentication Protocol

5. Security Analysis

This section evaluates the security of the proposed LightSecurePUF protocol through both informal analysis and formal verification. The informal analysis demonstrates the protocol's resistance to common attacks under the assumed threat model, while the formal analysis uses the Scyther verification tool under the Dolev-Yao adversarial model to verify authentication and secrecy properties.

5.1 Informal Security Analysis

Conversely, the UAV authenticates the Ground Station by verifying the HMAC received in Message 2. Generation of a valid HMAC requires knowledge of both the long-term shared secret and the challenge-dependent PUF response incorporated into the derived session key. Therefore, only a legitimate Ground Station can generate a valid authentication message.

After successful verification of Message 3, both entities obtain explicit confirmation that mutual authentication has been completed.

B. Replay Attack Resistance

Replay attacks are prevented through the use of fresh random nonces and together with the session identifier . Every protocol execution generates new authentication parameters and a new session key. Consequently, replaying previously captured protocol messages produces authentication values that are inconsistent with the current session and are therefore rejected during HMAC verification.

C. Man-in-the-Middle Attack Resistance

Under the Dolev-Yao threat model, an adversary may intercept, modify, delay, or fabricate protocol messages.

Unlike conventional lightweight authentication protocols that rely solely on stored cryptographic secrets, the proposed protocol integrates a challenge-dependent PUF response into both the authentication procedure and the session key derivation process. Consequently, successful authentication depends on the physical characteristics of the enrolled UAV hardware in addition to cryptographic credentials, providing an additional layer of protection against device cloning and hardware impersonation.

5.2 Formal Security Verification Using Scyther

To complement the informal analysis, the proposed protocol was formally verified using the Scyther protocol verification tool. Scyther performs symbolic protocol analysis under the Dolev-Yao adversarial model, where an attacker has complete control over the communication channel but cannot break the underlying cryptographic primitives.

The protocol was modeled using the Security Protocol Description Language (SPDL). The Scyther model includes the UAV and Ground Station roles together with authentication, agreement, synchronization, and secrecy claims as shown in Figure.3.

The following security properties were verified:

• Alive
• Weak Agreement
• Commit Authentication
• Non-injective Agreement (Niagree)
• Non-injective Synchronization (Nisynch)
• Secrecy of the long-term shared secret
• Secrecy of the PUF enrollment key
• Secrecy of the fresh nonces

Scyther reported “No attacks within bounds” for all specified claims, indicating that no attack violating the modeled security properties was discovered within the explored state space.

Table 3: Scyther Verification Results

Since UAVs operate under strict energy and processing constraints, reducing authentication overhead is essential for extending operational lifetime and supporting real-time communication.

6.1 Computational Cost Analysis

The computational complexity of an authentication protocol depends primarily on the cryptographic operations executed during one authentication session. The proposed protocol employs only lightweight operations, namely one-way hash functions, Hash-based Message Authentication Codes (HMACs), and Physically Unclonable Function (PUF) evaluations. It avoids computationally intensive public-key cryptographic operations such as elliptic curve scalar multiplication, modular exponentiation, and bilinear pairings.

Computational Cost of the Proposed Protocol

During one authentication session, the UAV performs:

• One PUF evaluation
• Two hash operations (one for session-key derivation and one within HMAC)
• Two HMAC computations

Similarly, the Ground Station performs:

• One PUF verification
• Two hash operations
• Two HMAC computations

Because all employed cryptographic primitives are lightweight, the proposed protocol is suitable for resource-constrained UAV platforms.

6.2 Communication Cost Analysis

Assuming typical field sizes shown in Table 4, the total communication overhead can be estimated.

Table 7: Communication Cost Comparison

6.4 Discussion

The performance evaluation demonstrates that the proposed protocol satisfies the requirements of lightweight UAV authentication. By relying exclusively on hash functions, HMACs, and PUF evaluations, the protocol avoids expensive public-key cryptographic operations that increase execution time and energy consumption. Furthermore, the three-message authentication exchange minimizes communication overhead while establishing a fresh session key and achieving mutual authentication. The integration of the PUF into session-key derivation distinguishes the proposed protocol from several existing lightweight schemes that use the PUF only for device authentication.

7. Conclusion

This paper proposed LightSecurePUF, a lightweight mutual authentication and session key establishment protocol for secure UAV-Ground Station communications. The protocol integrates a challenge-response Physically Unclonable Function with cryptographic hash functions and HMAC operations to provide hardware-assisted device authentication while maintaining low computational complexity. Unlike conventional lightweight authentication schemes that use the PUF only for identity verification, the proposed protocol incorporates the challenge-dependent PUF response into the session-key derivation process, thereby strengthening both authentication and key establishment.

The protocol requires only lightweight cryptographic primitives and a three-message authentication exchange, making it suitable for resource-constrained UAV platforms and wireless IoT environments.

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