In recent years, sensor networks are often deployed in several geographical regions to study certain phenomena. In this case, it may therefore happen that it is necessary to send a message to all the nodes of one or more regions for example to ask them to go into sleep mode. This problem is known in the literature as geographical routing (geocast). Several works have been proposed to solve this problem. In this paper we propose an energy-efficient and secured geocast protocol for a WSN deployed in space with data guarantee delivery to all nodes placed in one or more geocast regions. Our protocol consists of two major parts which are complementary and in addition of being secured, it is energy-efficient due to the fact that few messages are exchanged between the sensors during the first part of the algorithm.