The anomaly of cheap complexity

How does one design an electric motor? Would you attach a bathtub to it, simply because one was available? Would a bouquet of flowers help? A heap of rocks? No, you would use just those elements necessary to its purpose and make it no larger than needed – and you would incorporate safety factors. Function controls design.

– Prof. Bernardo de la Paz in The Moon Is A Harsh Mistress (Robert A. Heinlein)

Why are computer systems not very secure? Because they are composed of many complex layers. Why is it so even for simple applications like counting up votes or regulating temperature? It’s because today it’s easier and cheaper to build complex systems than it is to build simple ones.

Suppose you need a machine that does something not that complex, like a fridge. Complex general-purpose CPUs are cheap because of economies of scale and Moore’s law (ARM Cortex-M0 CPUs cost pennies). Software specializes a CPU that could do anything (universal computation) to become a device that does something.

Similarly a (huge and complex) general-purpose operating system is free, but a simpler, custom-designed, perhaps more secure OS would be very expensive to build.

Source: https://www.schneier.com/blog/archives/2022/08/security-and-cheap-complexity.html