Dynamic distributed systems like peer-to-peer systems, overlay networks and mobile ad hoc networks must execute their applications using distributed resources and in a decentralized way. The structure (composition and topology) of these systems changes frequently due to nodes joining or leaving the network, or due to mobility, faults and networks partitions. Distributed algorithms projected to this class of systems must be able to deal with the occurrence of these events and to self-adapt dynamically the application according to changes in its execution environment. In this paper, we propose a dynamic, self-adaptable and intrusion tolerant certificate authority (CA) designed to operate in mobile ad hoc networks. This CA is composed by a set of mobile devices present in the network, which forms a group of servers that supports CA functions. This architecture is based on a dynamic systems model and was conceived to manage changes in the membership of the servers group. This paper introduces an algorithmic base that allows the CA to reconfigure itself, guaranteeing the availability and the inviolability of the certification service.