Cryptographic communication system terminal device, cryptographic communication system relay device, and cryptographic communication system control method

摘要

In the present invention, in one-time pad encrypted communication using a mobile terminal device, the mobile terminal device ascertains, prior to one-time pad encrypted communication processing, a one-time pad code key held by another mobile terminal device. Terminal devices 101, 102 periodically send self-held key ID lists to a relay device 201, and the relay device 201 receives and retains the key ID lists held by each terminal device. One terminal device confirms the key ID list held by the other terminal device with which one-time pad encrypted communication is desired by communicating via the relay device and determines whether encrypted communication is possible.