stop trying to put critical apps on a raspberry pi. you are paying for flexibility but you don't use it, and don't need it either. get a nuc, an old laptop, anything with reasonable specs.
Discussion
Pi still offers the best tdp for price, though. If you feel like it's an unreliable piece of equipment I suggest familiarizing yourself with the hardware watchdog. It's excellent, to be honest.
Raspberry Pi has serious problems when working with cryptography applicatios. So it's useless. Consider use mini-pcs.