CRYPTOGRAPHIC KEY DELIVERY SYSTEM FOR RADIO COMMUNICATION, CRYPTOGRAPHIC KEY DELIVERY METHOD FOR RADIO COMMUNICATION, AND CRYPTOGRAPHIC KEY DELIVERY PROGRAM FOR RADIO COMMUNICATION

摘要

PROBLEM TO BE SOLVED: To deliver a cryptographic key shared in encrypted communications to an unspecific user terminal without registering authentication information in advance in a cryptographic key delivery system for radio communications.;SOLUTION: Each user terminal 2 stores a community identifier (ID) and a cryptographic key Ka for attribute authentication in a community attribute storage part 25. A cryptographic key generation part 24 for communications of the first user terminal 2 generates a cryptographic key Kt for communications, an encrypting/decrypting part 23 encrypts the cryptographic key Kt by using the cryptographic key Ka for attribute authentication, and a couple of the community ID and the encrypted cryptographic key Kt (community information) is registered in a community directory server (server) 1. The other user terminal 2 downloads the community information from the server 1, its encrypting/decrypting part 23 decrypts the encrypted cryptographic key Kt by using the cryptographic key Ka, and a radio communication part 21 integrates the cryptographic key Kt and performs radio encrypted communications between the user terminals 2.;COPYRIGHT: (C)2004,JPO