Security's something you do in-depth. You might build a perfect app, which correctly sanitizes your DB inputs (and you're right, it's easy these days). That won't necessarily stop $developer making a little PHP interface long after you leave, which exposes your DB again.
I'm not up to the play with HMAC so can't confidently comment on that, but the point being made is that there is lots of SQL injection out there. Keeping the salt out of the DB seems like a not-insane way to help mitigate a compromise.
I'm not up to the play with HMAC so can't confidently comment on that, but the point being made is that there is lots of SQL injection out there. Keeping the salt out of the DB seems like a not-insane way to help mitigate a compromise.