Paper 2013/489

An Efficient Scheme for Centralized Group Key Management in Collaborative Environments

Constantinos Patsakis and Agusti Solanas

Abstract

The increasing demand for on-line collaborative applications has sparked the interest for multicast services, which in many cases have to guarantee properties such as authentication or confidentiality within groups of users.To do so, cryptographic protocols are generally used and the cryptographic keys, in which they rely, have to be managed (e.g. created, updated, distributed). The procedures to perform these operations are determined by the so-called Group Key Management Schemes. Many schemes have been proposed and some of them have been proven to be vulnerable. This is the case of the Piao et al. scheme, whose scalability/efficiency is very good but it is vulnerable to many attacks because its security is based on a ``weak'' mathematical problem, so it can be broken in polynomial time. Inspired by the concepts proposed in the Piao et al. scheme we have re-designed the protocol and we have founded it on a hard mathematical problem and tweaked some of the procedures. This way, we propose a new scheme that is efficient, collusion free, and provides backward and forward secrecy.