[_trb_]

I am an application security professional, and I created this account in order to make this post after reading many of the comments on this thread.

Many of the comments have great suggestions. However, very few talk about the most important part of creating mitigations and designing key management/crypto. What is the security target?

Before throwing new designs at a problem, the attackers and attack vectors must be defined. If you don't know who you are guarding against and what they will do (and what data they will steal), then how can you possibly say what is a good mitigation??

One might argue that the threat is obvious, but I'll guarantee you that there are dozens of threats here. List them. Prioritize them. Then mitigate them. It is helpful to fully understand the problem/solution space before jumping in with pepper's, salt's, extra databases, and solutions.