AbstractThe formal aspects underlying a novel distributed backup service are discussed. Strength and originality of the service lie in the combined adoption of an established information dispersal algorithm with a simplified version of an existing location service. Information dispersal makes our service threshold-secure in that the backup owner only needs participation of a pre-established threshold number of nodes to recompose a distributed backup. This means that the service is highly available as it tolerates a number of node breakdowns. Even the right threshold number of nodes cannot retrieve the backup on their own initiative. The location service adopted allows our service to work over non-organized, flat networks. Indirect advantages are the optimization of the total redundancy of data and the efficient management of resources. Our service has reached the stage of a proof-of-concept implementation.