Abstract: A key exchange system according to an embodiment includes: a plurality of terminals that perform key exchange; and a server that performs authentication of each of the terminals and mediation of the key exchange, in which the server includes a nonce generation unit that generates a nonce used when the authentication is performed between the server and the terminal by federation using OpenID Connect, a key generation unit that generates a public key and a secret key of token control encryption, a first transmission unit that transmits the nonce and the public key to the terminal, and a decryption unit that decrypts a ciphertext received from the terminal by using the secret key and a token received from the terminal, and the terminal includes an encryption unit that generates a ciphertext obtained by encrypting predetermined data by using the public key and a token generated from the nonce, a second transmission unit that transmits the ciphertext to the server, and a long-term secret string generation unit tha

Abstract: A communication system includes an information processing device that provides a video conference service; and communication terminals using the service. The information processing device records communication data related to a video conference encrypted and transmitted from each communication terminal in a first storage for the communication terminal; transmits, to the communication terminals, a ciphertext obtained by encrypting an encryption key capable of decoding each item of the communication data recorded in the first storage such that the encryption key can be decoded by the communication terminals; and transmits the communication data recorded in the first storage to the communication terminals.

Abstract: An encryption apparatus including a key storage unit that stores a secret key and a public key of public key encryption, and an encryption unit that encrypts communication data using the secret key and the public key.

Abstract: Provided is distribution device that distributes time information to at least one sensor device, the distribution device including a storage unit that stores a time adjustment amount to be used for adjusting a local time, a calculation unit that calculates a time difference between a reference time and the local time, an adjustment unit that calculates an adjusted local time by adjusting the local time by an amount equal to or less than the time adjustment amount, when the time difference is greater than the time adjustment amount, and a distribution unit that distributes time information of the adjusted local time to the sensor device.

Abstract: Provided is distribution device that distributes time information to at least one sensor device, the distribution device including a storage unit that stores a time adjustment amount to be used for adjusting a local time, a calculation unit that calculates a time difference between a reference time and the local time, an adjustment unit that calculates an adjusted local time by adjusting the local time by an amount equal to or less than the time adjustment amount, when the time difference is greater than the time adjustment amount, and a distribution unit that distributes time information of the adjusted local time to the sensor device.