Fav-Bft: an efficient file authenticity verification protocol for blockchain-based file-sharing system

Abstract

Compared with traditional file-sharing system, the blockchain-based file-sharing system shows its superiority, such as electronic money incentive mechanism, decentralisation, information tamper resistance and so on. Benefiting from those properties, it has attracted tons of users to participate in blockchain-based file-sharing and eventually forms an indestructible electronic library. However, with such a huge amount of files, the problem of file authenticity verification is still not resolved. This paper attempts to address the challenge of file authenticity verification for blockchain-based file-sharing system, specifically, verifying that the file is really stored by the claimer and needed by the file-downloader before the file is downloaded. We propose an efficient file authenticity verification protocol, named File Authenticity Verification Byzantine Fault Tolerant (FAV-BFT). We first apply Verifiable Delay Function to bind the shared file, and then reconstruct it to a challenge-response interactive protocol for file-sharing, and finally embedded with Byzantine Fault Tolerant protocol. Due to the construction, with 2/3 of participants are honest, FAV-BFT can correctly prove how long a file has been stored and whether a file meets the requirement of the file downloader. Moreover, since all the file content is processed by hash function before transformation, FAV-BFT protects the shared-file from content disclosure during the verification process without trusted third parties. © 2022, ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering

Keywords: Authenticity verification, Blockchain, Efficient, File-sharing