I generally store mine in the fridge in zip-locks and have germed seeds that are several years old.
The good news is that Cannabis seeds are extremely hardy.If you look at the plants normal lifecycle outdoors,the seeded female dies at the end of the fall and over the course of the winter the seeds are exposed to sunlight,rain and some times freezing or extremely fluxuating temperatures.After all that abuse they still germ and continue to propagate themselves with no human intervention.
I don't use rice or silica gel.I've given some thought to those processes and I'm not convinced it is necessary.
A completely dry seed will not germanate,it will not sink in a glass of water because it is non-viable.
Cannabis seed must retain some moisture to remain viable.If you cut a seed in half and look inside you'll find it looks just like the meat of a nut,not dry but not wet either.I believe that most nuts contain about 5% moisture,my guess is that cannabis seeds probably contain about the same.
I think maybe the desiccant thing is carried over from pollen storage where moisture is will destroy the pollen.