Abstract: A receiving device sends challenge information to a transmitting device. The transmitting device initializes a time varying parameter and transmits communication data together with data derived from the challenge information to the receiving device. Subsequent communication data, if any, are then transmitted together with data derived from the time varying parameter. The receiving device uses the challenge information to verify the freshness of the communication data transmitted first, and uses the time varying parameter to verify the freshness of the subsequent communication data. Freshness can be verified without having to maintain any type of verification data during sleep periods, and without having to send a separate challenge for each data transmission.

Abstract: A communication method in which an operation, such as authentication, required when a new communication terminal participates in a mesh network is carried out in a more efficient manner. A second communication terminal that has already established an adjacent communication link with at least two first communication terminals, out of a plurality of communication terminals, distributes an adjacent terminal list including terminal identifiers of the first communication terminals along with a temporal key generated by the second communication terminal. One of the first communication terminals that received the adjacent terminal list and the temporal key distributes adjacent registration information, which is generated using a second temporal key.

Abstract: A transmission terminal includes an information generation unit, a transmission unit, a delivery management unit, and a reception unit. The information generation unit generates information that is to be transmitted to a destination reception terminal. The transmission unit transmits information that the information generation unit has generated. The delivery management unit manages transmission of information. The reception unit receives information that the destination reception terminal transmits. Furthermore, the information generation unit generates or receives transmission information that is to be transmitted to the destination reception terminal and generates redundant information for the destination reception terminal to restore the transmission information.

Abstract: Each node in a communication system receives state variable signals from other nodes indicating the internal operating states or internal timing of the other nodes, and transmits a state variable signal indicating its own internal operating state or timing. Each node also determines whether each received state variable signal is valid. Transitions in the internal operating state or timing of a node take place at a basic transition rate but at times adjusted according to the valid state variable signals received from other nodes. A group of neighboring nodes transmitting data signals can thereby autonomously reach a steady state in which their data signals do not collide, without having their timing control disrupted by reflected state variable signals or other invalid state variable signals.

Abstract: A wireless network system, information providing apparatus and wireless terminal that can prevent the leak of information such as an address of the wireless terminal. A wireless network system includes an information providing apparatus that provides service information over a wireless network, and multiple wireless terminals each of which receives the service information provided from the information providing apparatus. In this case, the information providing apparatus includes destination possibility data in the service information, and each of the wireless terminals determines the destination possibility that the destination of the provided service information is the wireless terminal based on the destination possibility data included in the provided service information accepts the provided service information only if it is determined that there is the destination possibility.

Abstract: This invention provides a message authentication system including: a message sending device having a send notice information generating unit that generates a first authentication code to certify a message and a second authentication code to certify the first authentication code and that sends the message and an authentication code generation key after authenticating reception certification information for the send notice information from a message receiving device; and including the message receiving device having a reception certification information generating unit that generates the reception certification information to certify the receiving of the send notice information, a first authentication code authenticating unit that authenticates the first authentication code by using the second authentication code and the authentication code generation key, a message authenticating unit that authenticates the message by using the authenticated first authentication code and the authentication code generation key.

Abstract: There is provided an unauthorized terminal inferring device (100) device that is connected to a plurality of communications terminal devices (IDi) by a multi-hop network.

Abstract: The invention provides a key update system for a multihop network system including an authentication management device that manages keys using a hierarchical structure. That device constructs key information having a hierarchical structure in accordance with the structure of the multihop network. In addition, that device determines respective encryption keys for encrypting the keys based on the key information, and the communication terminals obtain the respective keys. In this system, that device includes a key tree management portion that constructs and manages the key information; an encryption portion that encrypts the keys using the keys included in the key information; and a transmission portion that transmits the encrypted keys. Each communication terminal includes a receiving portion that receives the encrypted keys; a key management portion that manages the keys that need to be held and stored by the given communication terminal; and a decryption portion that decrypts the encrypted keys.

Abstract: In a message authentication system in which a message is transmitted from a message transmission apparatus 100 to individual message reception apparatuses 120 through wireless communication connecting the message transmission apparatus 100 with the message reception apparatuses 120 via intermediary message reception apparatuses and the message is authenticated at each message reception apparatus, the message transmission apparatus first transmits an electronic signature to each message reception apparatus as a message transmission notification and then transmits the message and an authentication key to the message reception apparatus after allowing a predetermined time lag. Thus, the message reception apparatus does not need to hold the message before the authentication key is published (FIG. 7).

Abstract: A message sending device sends a message. A message receiving device generates reception authentication information of the message when receiving the message, and further generates reception confirmation information of the message by using the reception authentication information of the message, to send the reception confirmation information of the message to a reception confirmation information verification device. The reception confirmation information verification device verifies the received reception confirmation information. The message sending device obtains a reception confirmation of the message for the message receiving device based on the verification result. This configuration reduces a processing load in each node as much as possible for confirming whether data to large numbers of nodes under a multihop environment have been received in each node.

Abstract: Each node in a communication system receives state variable signals from other nodes indicating the internal operating states or internal timing of the other nodes, and transmits a state variable signal indicating its own internal operating state or timing. Each node also determines whether each received state variable signal is valid. Transitions in the internal operating state or timing of a node take place at a basic transition rate but at times adjusted according to the valid state variable signals received from other nodes. A group of neighboring nodes transmitting data signals can thereby autonomously reach a steady state in which their data signals do not collide, without having their timing control disrupted by reflected state variable signals or other invalid state variable signals.