Patent ID: 7840011
Filing Date: 2010-11-23
Classification: H04L

Abstract:
1. A restoration apparatus comprising: a communication unit for communicating with a server group that, to store secret information, distributes to a plurality of servers a plurality of mixed images that are generated for each of N sets of distributed information that have been generated by distributing secret information using a threshold secret sharing scheme, wherein N is an integer of at least three, said plurality of mixed images being generated by converting the N sets of distributed information into N sets of image data and by mixing at different mixing ratios an image based on the distributed information with (Ka−1) dummy images, where Ka is an integer that satisfies 1<Ka<N; an acquisition unit for transmitting to the plurality of servers via the communication unit Kb passwords, where Kb is an integer that satisfies 1<Kb<N, entered by a user, and for obtaining from the plurality of servers at least Ka mixed images for each of Kb sets of the distributed information; a first restoration unit for restoring the Kb sets of distributed information based on the Ka mixed images that are obtained for the distributed information; and a second restoration unit for restoring the secret information using the Kb sets of distributed information that have been restored.