Vroomp got it right on. Cedar is definitely not the way to go as all Cedar comes with an odor that will "infuse" the cigars and you do not want that.
Spanish Cedar is from the Mahoganny family, not even cedar per say. Many humidors use mahogany, I've read that Honduran mahogany has certain similar properties with Spanish cedar but it won't emit the particular odor that pest dislike but smokers don't, which is the #1 reason for using it in humidors.
It has to be natural wood, untreated and as odorless as possible. But what's a couple thousand bucks in wood when it comes to storing our precious collections