A coding theory foundation for the analysis of general unconditionally secure proofofretrievability schemes for cloud storage
Paterson, Maura B. and Stinson, D.R. and Upadhyay, J. (2013) A coding theory foundation for the analysis of general unconditionally secure proofofretrievability schemes for cloud storage. Journal of Mathematical Cryptology 7 (3), pp. 181277. ISSN 18622976.

Text
PORrevisedv2.pdf  Author's Accepted Manuscript Download (411kB)  Preview 
Abstract
There has been considerable recent interest in “cloud storage” wherein a user asks a server to store a large file. One issue is whether the user can verify that the server is actually storing the file, and typically a challengeresponse protocol is employed to convince the user that the file 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 proofofretrievability 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 errorcorrection in a certain code. We provide a general analytical framework for such schemes that yields exact (nonasymptotic) reductions that precisely quantify conditions for extraction to succeed as a function of the success probability of a proving algorithm, and we apply this analysis to several archetypal schemes. In addition, we provide a new methodology for the analysis of keyed POR schemes in an unconditionally secure setting, and use it to prove the security of a modified version of a scheme due to Shacham and Waters [Lecture Notes in Comput. Sci. 5350, Springer (2008), 90–107] under a slightly restricted attack model, thus providing the first example of a keyed POR scheme with unconditional security. We also show how classical statistical techniques can be used to evaluate whether the responses of the prover are accurate enough to permit successful extraction. Finally, we prove a new lower bound on storage and communication complexity of POR schemes. This paper treats proofofretrievability 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 errorcorrection in a certain code. We provide a general analytical framework for such schemes that yields exact (nonasymptotic) reductions that precisely quantify conditions for extraction to succeed as a function of the success probability of a proving algorithm, and we apply this analysis to several archetypal schemes. In addition, we provide a new methodology for the analysis of keyed POR schemes in an unconditionally secure setting, and use it to prove the security of a modified version of a scheme due to Shacham and Waters under a slightly restricted attack model, thus providing the first example of a keyed POR scheme with unconditional security. We also show how classical statistical techniques can be used to evaluate whether the responses of the prover are accurate enough to permit successful extraction. Finally, we prove a new lower bound on storage and communication complexity of POR schemes.
Metadata
Item Type:  Article 

Keyword(s) / Subject(s):  Proofofretrievability, cloud storage, errorcorrecting code 
School:  School of Business, Economics & Informatics > Economics, Mathematics and Statistics 
Depositing User:  Maura Paterson 
Date Deposited:  16 Jan 2014 09:19 
Last Modified:  11 Feb 2021 07:12 
URI:  https://eprints.bbk.ac.uk/id/eprint/8968 
Statistics
Additional statistics are available via IRStats2.