Have you ever considered the NSA or other government contractors? The standard way to get a job as a mathematician at the NSA is to apply for one of their development programs, which lets you tour around through several different groups within the NSA (but all would be in Maryland, probably) for 3 years and then settle down into one you like. They love math phds with some computer science background, and they pay more for those with a phd than for those coming out of bachelor's (so you wouldn't have "wasted your time" getting the degree; it would show up in your salary and promotion prospects).

Note that in order for this to work for you, you have to be a US citizen and you have to be able to pass a fairly invasive background check to get a top secret clearance. From when you apply to when you start working there might be 9 or 10 months. The development programs are called things like "The Applied Math Program" but I don't believe the math is any more applied than graph theory (though I can't know for sure). I know several pure mathematicians who are perfectly happy there. They don't get to research whatever they like, but they do get to choose problems from a list of problems and they seem to be pretty interested in what they do.

The other benefit of the government route is that there are contractors all over the place you could also go work for. There's even one in San Diego. It's called IDA (Institute for Defense Analyses). You can apply for those at the same time as you're applying for the NSA, or you could apply after the development program was done. Tread carefully here, I imagine the NSA doesn't like to lose people they've trained to other agencies, any more than any job would like losing people they've trained to a higher paying job. I only mention this in case living in CA is important to you.

Good luck!