A method for sharing a secret key between a source node and a destination node includes (a) adding, at each forward intermediate node, a secret key between the forward intermediate node and a node before the forward intermediate node to the secret key sharing request message; (b) generating a shared secret key between the source node and the destination node from the secret key between the forward intermediate node and the node before the forward intermediate node added in the secret key sharing request message; (c) adding, at each backward intermediate node, a secret key between the backward intermediate node and a node before it to the secret key sharing response message; and (d) generating the shared secret key between the destination node and the source node from the secret key between the backward intermediate node and the node before it added in the secret key sharing response message.