Reliable delivery route computation for threshold secret shared content

A threshold secret sharing scheme can protect content by dividing it into many pieces and distributing them over different servers. This scheme can also be utilized for reliable delivery of the content. Thanks to this scheme, the receiver can still reconstruct the original content even if several pieces are lost on their delivery routes due to the occurrence of a multiple-link failure. This paper aims to obtain reliable delivery routes for the pieces, as this will minimize the probability that the receiver cannot reconstruct the original content. Although such a route optimization problem can be formulated using an ILP (Integer Linear Programming) model, optimum route computation based on the ILP model requires large amounts of computational resources. Thus, this paper proposes a lightweight method for computing suboptimum delivery routes. The proposed greedy method computes each of the delivery routes successively by using the conventional shortest route algorithm repeatedly. The distance of the links is adjusted iteratively on the basis of the given probability of failure on each link and utilized for the calculation of each shortest route. The results of a performance evaluation show that the proposed method based on the strict adjustment of the link distance can compute sufficiently optimum delivery routes at less than 100 seconds, even in backbone networks of a practical scale.