: Group key management has received a particular attention, these last years, in both academic and industry research communities. This is due to the economical relevance of group-based applications, such as video on demand, video-conferencing, collaborative work, and so forth. The dynamic aspect of group applications due to free membership joins and leaves in addition to members' mobility, makes security further challenging in the context of group communications. In this paper, we propose a novel key management approach based on adaptive clustering of encryption areas in order to tackle both scalability and dynamism issues in secure group communications. We demonstrate the pertinence of our solution through a proof of optimality with respect to the stated optimisation problem, and simulation results that illustrate when and how our solution outperforms other approaches proposed in the literature.