Abstract: According to one embodiment, an encryption communication system configures a network with a plurality of nodes, and shares the encryption key between a first node that delivers the encryption key to a first user and a second node that delivers the encryption key to a second user. The first node forms n (n>1) systems of paths to the second node over the network, generates n pieces of first data, distributes the n pieces of first data to the n systems of paths and transmits the n pieces of first data to the second node, and generates the encryption key by superimposing the n pieces of first data. The second node receives the n pieces of first data from the first node via the n systems of paths, and generates the encryption key by superimposing the n pieces of first data.