Social networks are increasingly becoming essential for users to connect and share information, whether for personal, professional, or recreational purposes. A rising trend is the daily sharing of photos on online Social Network Platforms (SNPs), where the privacy of these photos is often protected by security mechanisms. However, the effectiveness of these mechanisms diminishes once the photos are shared across different platforms. This project proposes a block chain-based secure photo-sharing framework that enhances photo dissemination control across heterogeneous social networks. Unlike traditional security mechanisms that operate on centralized servers, this framework uses block chain technology to achieve a consistent consensus on photo-sharing control through smart contract protocols. The proposed protocols ensure platform-free dissemination trees for every image, giving users complete control over their sharing preferences while maintaining privacy. Additionally, this system introduces a dynamic privacy policy generation algorithm, which maximizes the flexibility of re-posters without compromising the privacy of original owners.