In hybrid peer-to-peer type content delivery, a server confirms user’s intension as to content disclosure, guarantees content delivery by mutual authentication between a client to which content has been delivered and a client to which content has not been delivered, and guarantees the integrity of content having been delivered. The collapsible table includes a feet unit having two horizontal rods, a plurality of feet each having an upper end pivotally connected to one end of the horizontal rod. When the blocking unit is closed, the power take-off connecting pieces are connected to the corresponding supply connecting pieces and, when the blocking unit is open, they are detached from the supply connecting pieces.