> predict the presence, make, model & operational schedule of someone's washing machine just by observing how fast their power meter spins over time I think th

> predict the presence, make, model & operational schedule of someone's washing machine just by observing how fast their power meter spins over time I think this is a really excellent analogy that explains the situation well. However, I think doing exactly that would be really straightforward, and your analogy explains why. Imagine an ML model constantly adjusting the probabilities for the set of possible washing machines... after a large number of washing machine runs, it will be narrowed down to a really small subset of the possibilities. Given that this is a cryptographic key, they can then trivially brute force the remaining possibilities.