ICMC19: IoT TLS: Why is it Hard?

David Brown, Senior SW Engineer, Linaro, United States

For reasons we can't really explain, we now have things like our lightbulbs, toasters and fridges on the Internet... now those devices are vulnerable to attack.

5 worst examples: Jeep Hack, Mirai Botnet, Hackable Cardiac Devices, Owlet WiFi Baby Heart Monitor and Trendnet webcam hack. In the Jeep example, they had a lot of great controls in place, but not on who could update the firmware...

James Mickens was quoted as Saying "IoT Security is not Interesting". It's not interesting, because it's not different. We already know how to secure devices... so we should do it! TLS is great - so let's just use that!

But, we have some really tiny devices out there - smaller than a Raspberry Pi. They have maybe less than 10s of KB of Memory, and 10s MHz of CPU... how can we do TLS there?

TLS has a way of specifying which cipher suites can be used during the handshake. It's hard to change what an IoT device is using, so how can a service just start rejecting something?

One of the problems is that lots of folks do not implement TLS correctly - TLS done incorrectly is worse than not doing it at all.

TLS requires memory, time and randomness - all things that are in short supply on IoT devices!

Some suggestions are to pursue stream abstraction or to put TLS under te socket API, but those don't really work.

Looking at Sockets + TLS now, Zephyr network API changes, JWT, time, MQTT...