Device-to-device IoT system-based security protocol for agreeing on social meetings

The Internet of Things (IoT) comprises a wide range of interconnected devices capable of autonomous communication. As these devices exchange sensitive information, ensuring secure communication becomes critical. This paper addresses the challenge of securing peer-to-peer communication in IoT environments, particularly in scenarios involving social meeting arrangements. We propose a dedicated security protocol supporting device-to-device interactions for coordinating real-world meetings based on users’ proximity preferences. The protocol includes an initialisation phase, session key establishment, and a secure communication phase. Additionally, we present a supporting theoretical framework involving user applications, a semi-trusted server, and an algorithm for optimal meeting point selection. To validate the protocol’s effectiveness, we conduct a comprehensive evaluation using formal methods (BAN logic), informal reasoning, and automated verification tools. The results confirm that our protocol ensures key security properties, including mutual authentication, anonymity, revocation support, and resilience against common cyberattacks such as impersonation, replay, and man-in-the-middle attacks. To our knowledge, this is the first verified D2D protocol designed for real-time, privacy-aware social meeting coordination without relying on centralised infrastructure.