The rule is, "data in motion should be secured with TLS, data at rest should be secured with PGP".
Isn't this more of a heartfelt wish than a rule, though? It's restrictive enough to be impractical, I would guess even for security researchers. Do you use SSH to access remote machines?
If your problem doesn't fit into PGP or TLS, refactor your problem.
There are high-level crypto libraries (though none that I recommend without hesitation) that provide essentially the same features as PGP. If you're going to make a concession, perhaps that's the one you could consider. However:
* I don't recommend doing so, and
* It's not that much of a concession, because you still have to wrap your application around the cryptosystem, not the other way around.
Isn't this more of a heartfelt wish than a rule, though? It's restrictive enough to be impractical, I would guess even for security researchers. Do you use SSH to access remote machines?