Tangible security: Survey of methods supporting secure ad-hoc connects of edge devices with physical context.

Edge computing is the concept of moving computation back to the endpoints of a network, as an alternative to, or in combination with, centralized, cloud-based architectures. It is especially of interest for Internet-of-Things and Cyber-Physical Systems where embedded endpoints make up the edge of the network, and where these devices need to make localised, time-critical decisions. In these environment secure, ad-hoc device-to-device interaction is important, but offers a challenge because devices might belong to different systems, or security domains, which complicates trusted communication and key establishment. There has been a growing interest in complementing conventional cryptography with physical context. This allows for services that are difficult to achieve with existing cryptographic mechanisms: devices pairing (initial key establishment) and proof-of-proximity (ensuring devices are physically present). Numerous methods, the majority of which are based on the physical context of device characteristics, behavior or environment, have been proposed to supplement cryptography in achieving these services. This paper provides an overview of this area of research, first discussing the nature and importance of the two specified security services in ad-hoc communication settings and then providing an introduction to prominent physical context security approaches in literature.