As an ancap, I believe the common ancap philosophy is wrong here. Contracts are central to all transactions. Most contracts are implicit, e.g. If you enter my store, you will not pocket things from the shelf and walk out without paying. I don't think the present system of copyright and patent law is not justified because it is redundant to individual contracts and makes litigation onerous. However the essence of protecting information with agreements is fully in harmony with the fundamental principals of free association and anarcho-capitalism.