The Energy Cost of SSL in Deeply Embedded Systems
The Energy Cost of SSL in Deeply Embedded Systems
20 June 2008
As the number of potential applications for tiny, battery-powered, "mote"-like, deeply embedded devices grows, so does the need to simplify and secure interactions with such devices. Embedding a secure web server (capable of HTTP over SSL, aka HTTPS), enables these devices to be monitored and controlled securely via a user-friendly, browser-based interface.
This paper presents the first empirical energy analysis of the Internet's dominant security protocol, SSL, on highly constrained devices. We have enhanced Sizzle, our tiny-footprint HTTPS stack, with energy conserving features and measured its performance on a Telos mote. We show that the key exchange phase, which consumes much more energy than bulk encryption and authentication, amortizes well over the transmission of a few kilobytes of application data. Such amortization is easily attained with features like session reuse and persistent HTTP(S), both of which are supported by Sizzle. The extra energy cost of encrypting and authenticating application data with SSL is around 15%. With the addition of an application-level, duty-cycle based approach to low-power listening for incoming service requests, a pair of alkaline batteries can power Sizzle for over a year under a variety of application scenarios.
Venue : N/A
File Name : smli_tr-2008-173.pdf