Date Added: Oct 2012
There has been considerable recent interest in "Cloud storage" wherein a user asks a server to store a large le. One issue is whether the user can verify that the server is actually storing the le, and typically a challenge-response protocol is employed to convince the user that the le is indeed being stored correctly. The security of these schemes is phrased in terms of an extractor which will recover or retrieve the file given any "Proving algorithm" that has a sufficiently high success probability. This paper treats proof-of-retrievability schemes in the model of unconditional security, where an adversary has unlimited computational power. In this case retrievability of the file can be modelled as error-correction in a certain code.