Initial Distribution of Group Keys for Confidential Group Communication

Traditional methods for the initial distribution of group keys based on encryption and digital signature cannot effectively protect the privacy of a new member who joins a confidential group since the digital signature allows anyone to verify it using the public key. When joining such a group, a new member may not want to make private information, such as the group it joins, the group manager and especially the entity who issues the admission token, available to the general public to prevent the information from being disclosed to an adversary. In this paper, we propose two schemes for the initial distribution of group keys for confidential group communication based on elliptic curve ElGamal encryption and directed signature with the property that the signature can only be verified by the designated receiver. We show through experiments using statistical hypothesis t-test two samples for means that our schemes can effectively protect the privacy of a new joining member at the cost of little computation resources.