I want to experiment with the use of sensors for data logging and potentially for automated actions based on data properties. An example of the latter is if a value being monitored exceeds a threshold for X amount of intervals, some kind of notification or response is triggered, whether an LED lighting up or email being sent out.
I'm not an expert about sensors, networking, IoT, robotics, scripting, machine learning, or programming in general. That's all part of the learning process. I know enough to know security is important and easier to achieve if it's a goal from the beginning. So my question as I embark on this learning excursion is, what do I need to be aware of or control for to keep these systems safe as I create and experiment with them? If that question is so broad a book answers it, could you recommend a learning resource? Where does one start for learning how to keep home brewed IoT systems secure?
I realize this depends on two major things: security is harder as complexity increases; and security depends on threat models. Well, my simple sensor systems are bound to get more complex if I pursue more significant projects with them, thus the importance of good security that scales from the start. As for threat models, I don't anticipate enemies and these would all be relatively low-value and plentiful targets (many sensors monitoring basic things) but I do expect there are malicious agents seeking to control any processing power they can or disrupt systems just for the sake of chaos. Lastly as an importart part of the threat model is physical security, because if I put a sensor outside with a solar panel to power it, how do I stop mischievous kids or crooks from destroying or stealing the technology?