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

摘要

In one-time pad encryption communication using a mobile terminal device, the mobile terminal device grasps a one-time pad encryption key held by another mobile terminal device before the one-time pad encryption communication processing. The terminal apparatuses 101 and 102 periodically transmit the key ID list that the self-confidence possesses to the relay apparatus 201, and the relay apparatus 201 receives and retains the retained key ID list of each terminal apparatus. The terminal device performs communication via the relay device, thereby confirming the possessed key ID list of the partner terminal device with which one-time pad encryption communication is to be performed, and determines whether encryption communication is possible.