Probabilistically secure cooperative distributed storage

The trend towards self-organization of systems like peer-to-peer or mobile ad hoc networks generates increasing needs for distributed data management, in particular data backup and distributed storage functions that will themselves be self-organized and cooperative. Unfortunately, in such systems, the data stored are exposed to the selfishness (e.g. data discarded because of lack of resources) or to the maliciousness (e.g. data voluntarily discarded for disruption of data storage functionality) of participating nodes. This setting, combined with the high churnout of nodes in such systems, makes it quite uneasy to determine the actual availability of some data stored cooperatively. We propose in this report the combination of probabilistic and cryptographic verifications to evaluate this availability and possibly react as it becomes less probable. After reviewing existent approaches to distributed data storage protection, we present a protocol for determining the availability of data stored in a distributed fashion with various degrees of criticality.