Anonymous communication system and method for subscribing to said communication system

Abstract

[Problem] To provide an anonymous communication system which ensures anonymity, with which a user can be identified if necessary, and which has a high degree of social credibility. [Solution] A user computertransmits to a management computerelectronically signed subscription application data signed using a first signature key capable of being used with another communication system. The management computerverifies the electronic signature of the subscription application data using a first public key, and if the validity of the electronic signature can be verified, generates and encrypts a second signature key and transmits the encrypted second signature key to the user computer. The user computergenerates electronically signed receipt data that have been signed in duplicate using the first and second signature keys, and transmits the receipt data to the management computer. The management computerverifies the electronic signature of the receipt data using first and second public keys, and if the validity of the electronic signature can be verified, records user data including the receipt data in a recording unit