@techreport{discovery10153741,
            year = {2021},
           title = {Recurring Contingent Payment for Proofs of Retrievability},
       publisher = {Cryptology ePrint Archive},
           month = {September},
          series = {Paper 2021/1145},
            note = {This work is licensed under an Attribution 4.0 International License (CC BY 4.0).},
             url = {https://eprint.iacr.org/2021/1145},
        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 a "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.},
          author = {Abadi, Aydin and Murdoch, steven and Zacharias, Thomas},
        keywords = {Cryptographic protocol, blockchain, smart contracts, fair exchange}
}