I'm working on the German Corona-Warn-App project and currently investigating possibilities for interoperability between different exposure notification systems/backends. Do you already have plans on how the CovidShield server can exchange key data with other deployments? The exposure notification reference server provides a specification for a federation API which can be used for an authorized exchange of daily keys (TEKs) between different server deployments. Is this federation API something you might consider to integrate into the CovidShield server?