Scrutinizing the Vulnerability of Ephemeral Diffie–Hellman over COSE (EDHOC) for IoT Environment Using Formal Approaches

Most existing conventional security mechanisms are insufficient, mainly attributable to their requirements for heavy processing capacity, large protocol message size, and longer round trips, for resource-intensive devices operating in an Internet of Things (IoT) context. These devices necessitate efficient communication and security protocols that are cognizant of the severe resource restrictions regarding energy, computation, communication, and storage. To realize this, the IETF (Internet Engineering Task Force) is currently working towards standardizing an ephemeral key-based lightweight and authenticated key exchange protocol called EDHOC (Ephemeral Diffie–Hellman over COSE). The protocol’s primary purpose is to build an OSCORE (Object Security for Constrained RESTful Environments) security environment by supplying crucial security properties such as secure key exchange, mutual authentication, perfect forward secrecy, and identity protection. EDHOC will most likely dominate IoT security once it becomes a standard. It is, therefore, imperative to inspect the protocol for any security flaw. In this regard, two previous studies have shown different security vulnerabilities of the protocol using formal security verification methods. Yet, both missed the vital security flaws we found in this paper: resource exhaustion and privacy attacks. In finding these vulnerabilities, we leveraged BAN-Logic and AVISPA to formally verify both EDHOC protocol variants. Consequently, we described these security flaws together with the results of the related studies and put forward recommended solutions as part of our future work.