Specific applications like military or public emergency ones require secure group communication in ad hoc environments. The most suitable solution to provide the expected level of security to these services is the provision of a key management protocol. This paper shows the specific challenges towards key management protocols for securing multicast communications in ad hoc networks, and provides a taxonomy of these protocols in MANETs. A new approach, called BALADE, is also presented. It is based on a sequential multi-sources model, and takes into account both localization and mobility of nodes, while optimizing energy and bandwidth consumptions.