A Novel Conference Key Distribution System with Re-keying Protocol

Abstract

A conference key distribution system is designed to establish a common secret key so that a group of people are able to hold a conference securely. However, the existing conference distribution schemes do not consider the situation that a user may be in a conference for only a period of time. If a user resigned from this session and premeditatedly eavesdropped on data transmissions, he could then also decrypt the data. Thus, all messages are likely to be compromised during the span of the system. In this paper, we propose a new conference key distribution scheme with re-keying protocol in which all conference keys in a conference are different for each time period. Our goal is to minimize the potential damages over a public network. Once the time period has elapsed the participants in a conference cannot access any messages with previously used common keys. Therefore, if a user resigns from a conference and premeditatedly eavesdrops on later messages, he cannot decrypt the message with his old keys. Moreover, in our proposed scheme, we do not require a chairman (or trusted center) and any interactive protocols among all participants in order to construct the common conference key for each time period. It can be easily implemented to a dynamic conference key distribution system because other participants’ information items of the system need not be immediately changed once a participant is added or deleted.