Energy and Processing Demand Analysis of TLS Protocol in Internet of Things Applications

Transport Layer Security (TLS) is the de-facto protocol for secure communication in Internet of Things (IoT) applications. However, the processing and energy demands of this protocol are two essential parameters that must be taken into account with respect to the resource-constraint nature of IoT devices. In this paper, we study the resource consumption of the TLS handshake using a testbed in which an IoT board (Cypress CYW43907) communicates with a Raspberry Pi server over an 802.11 wireless link. Although TLS supports a wide-array of encryption algorithms, we focus on the performance of TLS using three of the most popular and robust cipher suites. Our experiments show that ciphers using Elliptic Curve Diffie Hellman (ECDHE) key exchange are considerably more efficient than ciphers using Diffie Hellman (DHE). Furthermore, ECDSA signature verification consumes more time and energy than RSA signature verification given ECDHE key exchange. The studies of this paper help IoT designers choose an appropriate TLS cipher suite based on application demands, computational capabilities, and available energy resources.