Key Management Protocol with Implicit Certificates for IoT systems

This paper proposes a Key Management Protocol for mobile and industrial Internet of Things systems, targeting, at the same time, robust key negotiation, lightweight node authentication, fast re-keying, and efficient protection against replay attacks. The proposed approach pragmatically leverages widely accepted Elliptic Curve Cryptography constructions, specifically the (Elliptic Curve) "Fixed" Diffie Hellman key exchange and the (Elliptic Curve) Qu-Vanstone implicit certificates. Our value added is their suitable integration into a security protocol exchange, designed at layer 2, in the 802.15.4 protocol stack, which permits to i) avoid Elliptic Point multiplications upon rekeying of previously paired devices, and ii) support mutual authentication while securing the protocol exchange. To prove its viability, the proposed Key Management Protocol has been implemented and assessed on severely constrained devices. As expected, but made explicit and quantified by our experimental performance evaluation, the usage of implicit certificates in conjunction with an optimized message exchange yields impressive gains in terms of airtime consumption with respect to state of the art schemes.