Key Management Method in Network System

The key management method in a network system is disclosed. Key management in a network system according to the present invention method may be different according to the key management method in a network system including at least one node group consisting of the node, the number of nodes in whole or in part subset sharing by each consisting of substituting step, step, and a key part of the input for each node storing a portion of the keys set for each node to set the keys in the predetermined function to be implemented by the step of generating a set remaining keys. According to the present invention, in transmitting the encrypted content and the encryption key update, it is possible to significantly reduce the number of keys required for each node is stored. Network, the key management, node, the hash function, a hash tree, chain, the key generation