Like the Web services, federated identity wins gradually businesses. The creation of an infrastructure of federated identity is a viable alternative to current systems. For employees or users, a federated identity leads to a better experience of the Internet, a greater level of customization, more security and a real control of this identity. In this work we propose choreography for a platform of federated identity based on mobile agents whose benefits will offer more autonomy and flexibility. The use of agents will be accompanied by a definition of ontology allowing them to rely on a single vocabulary, a structured description to better operate and cooperate