The lack of fixed infrastructure, both physical and organizational, and the highly dynamic nature of ad hoc networks, presents a major challenge in providing secure, authenticated communication for these networks. Traditional key management solutions reported in the literature lack both the flexibility and robustness required to cope with the dynamic nature of ad hoc networks. In this paper, we propose two different n-party authenticated key agreement protocols enabling authorized nodes to generate their own session keys. The first protocol introduces a solution based on clustering techniques suitable for networks with partial structure and composed of a large number of nodes. The second protocol assumes no structure and provides authentication with a minimal increase in communication and computational overhead required.