In the wet brining process, using salt and brown sugar, its supposed to be the combo that infuses the seasonings mixed with brine into the meat using osmosis.
That being said, other food experts say that crusting the meat with just salt is the way to go. I've never done that, but its on my agenda now.
I'm no expert but you asked about the dry brine process. If you rub salt only on meat and give it time the salt will dissolve into the meat, all the other spices will remain on the surface.
The wet brine process is different and I only use it on birds.