  Communication between connected objects in the Internet of Things (IoT) often
requires secure and reliable authentication mechanisms to verify identities of
entities and prevent unauthorized access to sensitive data and resources.
Unlike other domains, IoT offers several advantages and opportunities, such as
the ability to collect real-time data through numerous sensors. These data
contains valuable information about the environment and other objects that, if
used, can significantly enhance authentication processes. In this paper, we
propose a novel idea to building opportunistic sensor-based authentication
factors by leveraging existing IoT sensors in a system of systems approach. The
objective is to highlight the promising prospects of opportunistic
authentication factors in enhancing IoT security. We claim that sensors can be
utilized to create additional authentication factors, thereby reinforcing
existing object-to-object authentication mechanisms. By integrating these
opportunistic sensor-based authentication factors into multi-factor
authentication schemes, IoT security can be substantially improved. We
demonstrate the feasibility and effectivenness of our idea through illustrative
experiments in a parking entry scenario, involving both mobile robots and cars,
achieving high identification accuracy. We highlight the potential of this
novel method to improve IoT security and suggest future research directions for
formalizing and comparing our approach with existing techniques.
