Your data in Collaber is stored in all your devices(systems) along with in Collaber Server. This data is stored in un-encrypted format as any of your other data. But all communication between Collaber Client and Collaber Server happens through a secured encrypted channel(SSL).
Your data is stored in Collaber Server to facilitate importing of your account into any new system, use it as a always on backup, and access to your data through Web and Mobile devices.