I think CAN maps better to layer 1. You can and do blindly trust messaging at layer 1. In any piece of engineering there exists an abstraction level below which

I think CAN maps better to layer 1. You can and do blindly trust messaging at layer 1. In any piece of engineering there exists an abstraction level below which there is no security. Software people are prone to forget this because everything they do is virtual. But it's not turtles all the way down, there is no such thing as a secure transistor.