Some remarkable property of the uniformly random distributed archive scheme

We investigate security of a certain simple and fast scheme of distributed archive. The scheme, namely Uniformly Random Distributed Archive (URDA), distributes original source data across multiple storages in the Internet with redundancy. The most important feature of URDA is its stochastic process to determine storages to which fragments of the original data are to be delivered. By delivering each data fragment to randomly chosen n − k + 1 storages out of n storages, we can realize the followings: (1) If k storages are accessible, the original data can be completely reconstructed; (2) Even if an attacker compromises k − 1 storages, the entire original data will not be revealed. Moreover, we show that URDA has a remarkable property in terms of secrecy of archived data. The property is that, if an attacker compromises r storages (r < k) to obtain a part of the original data, the attacker can guess only with very small success probability where in the revealed part a particular data fragment appears. Although further study is necessary to reach full understanding of the security of URDA, this indicates that URDA can provide at least a certain good level of secrecy in addition to its excellent time-efficiency.