If I know more about the attack vectors maybe I can help more or maybe if there is a list of attack vectors for the community to research that would work. But my guess is the concerns are hardware and software vulnerabilities. Software you can solve by formal verification and correct by construction to make it bug free. Hardware it really depends on what you can afford and how determined the adversary is. Economic incentives can also be put into play to improve security. Incentive centered design can take care of that part using smart contracts: https://www.usenix.org/legacy/event/hotsec06/tech/full_papers/wash/wash.pdf