Cryptology ePrint Archive: Report 2021/1145

Recurring Contingent Payment for Proofs of Retrievability

Aydin Abadi and Steven J. Murdoch and Thomas Zacharias

Abstract: Fair exchange protocols let two mutually distrusted parties exchange digital data in a way that neither can cheat. At CCS 2017, Campanelli et al. proposed two blockchain-based protocols for the fair exchange of digital coins and a certain service, i.e., “proofs of retrievability” (PoR), that take place between a buyer and seller. In this work, we identify two serious issues of these schemes; namely, (1) a malicious client can waste the seller’s resources, and (2) real-time leakage of information to non-participants in the exchange. To rectify the issues, we propose “recurring contingent PoR payment” (RC-PoR-P). It lets the fair exchange reoccur while ensuring that the seller’s resources are not wasted, and the parties’ privacy is preserved. We implemented the RC- PoR-P. Our cost analysis indicates that the RC-PoR-P is efficient. The RC-PoR-P is the first of its kind that offers all the above features.

Category / Keywords: cryptographic protocols / Proofs of Retrievability, Fair Exchange, Blockchain, Smart contract

Date: received 9 Sep 2021

Contact author: aydin abadi at ucl ac uk, s murdoch at ucl ac uk, thomas zacharias at ed ac uk

Available format(s): PDF | BibTeX Citation

Version: 20210910:065307 (All versions of this report)

Short URL: ia.cr/2021/1145


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