Abstract: In a node device 1 in a communication network, an FID management table 5 stores an FID for unique identification of a frame and the information about a destination node of the frame, and a weighting table 7 stores weighting information about another node as a destination for relay of the frame for each final destination node of the frame. When a frame transmitted to a local node is received, and if the FID of the received frame is stored in the FID management table 5, the data about the destination node associated with the FID is updated. If the FID of the frame received from the frame reception device is not stored in the FID management table 5, the FID management table 5 corresponding to the destination node of the frame is referred to, and another node as a destination for relay of the frame is determined.

Abstract: A node apparatus changes a first access key unique to itself; changes a shared key same for node apparatuses; encrypts, using the shared key, the first access key and transmits it; receives an access key notification frame; decrypts it using the shared key, thereby obtaining a second access key; attaches, to a first plaintext frame, first signature data obtained by encrypting, using the shared key, data including a first value calculated from the first plaintext frame; encrypts the first plaintext frame using the second access key and transmits thus encrypted frame; receives a second encrypted frame; decrypts it by the first access key to obtain a second plaintext frame; obtains a second value by decrypting, using the shared key, a second signature data attached to the second plaintext frame; calculates a third value from the second plaintext frame; and confirms whether the second and third values are consistent.

Abstract: In a node device 1 in a communication network, an FID management table 5 stores an FID for unique identification of a frame and the information about a destination node of the frame, and a weighting table 7 stores weighting information about another node as a destination for relay of the frame for each final destination node of the frame. When a frame transmitted to a local node is received, and if the FID of the received frame is stored in the FID management table 5, the data about the destination node associated with the FID is updated. If the FID of the frame received from the frame reception device is not stored in the FID management table 5, the FID management table 5 corresponding to the destination node of the frame is referred to, and another node as a destination for relay of the frame is determined.

Abstract: A node apparatus changes a first access key unique to itself; changes a shared key same for node apparatuses; encrypts, using the shared key, the first access key and transmits it; receives an access key notification frame; decrypts it using the shared key, thereby obtaining a second access key; attaches, to a first plaintext frame, first signature data obtained by encrypting, using the shared key, data including a first value calculated from the first plaintext frame; encrypts the first plaintext frame using the second access key and transmits thus encrypted frame; receives a second encrypted frame; decrypts it by the first access key to obtain a second plaintext frame; obtains a second value by decrypting, using the shared key, a second signature data attached to the second plaintext frame; calculates a third value from the second plaintext frame; and confirms whether the second and third values are consistent.