A blockchain-based Privacy-Preserving Framework for Cross-Social Network Photo Sharing

Posting daily photos on online Social Network Platforms (SNPs) has become a trend. As a kind of sensitive privacy, social photos are often protected carefully by SNPs with various security mechanisms. However, these mechanisms can not stop users from losing control of their photos when someone forwards these photos to another platform. In this paper, we propose a blockchain-based privacy-preserving framework that provides powerful dissemination control for online photos in cross-social network sharing. In contrast to existing security mechanisms that run separately in centralized servers, which hardly create trust between each other, our framework achieves consistent consensus on photo dissemination control across independent and disparate platforms through carefully designed smart contract-based protocols. Considering the numerous participants in real photo dissemination, we present a novel concept of multi-owner dissemination tree to be compatible with all privacy preferences of subsequent forwarders in cross-SNPs photo sharing. This paper describes a prototype implementation on hyperledger Fabric 2.0 with demonstrating its preliminary performance by a real-world dataset and identifies the remaining challenges.