Online Social Networks (OSNs) constitute vital communication and information sharing channels. Unfortunately, existing coarse-grained privacy preferences insufficiently protect the shared information. Although cryptographic techniques provide interesting mechanisms to protect privacy, several issues remain problematic, such as, OSN provider acceptance, user adoption, key management and usability. To mitigate these problems, we propose a practical solution that uses Identity-Based Encryption to simplify key management and enforce data confidentiality. Moreover, we devise an Identity-Based outsider anonymous private sharing scheme to disseminate information among multiple users. Furthermore, we demonstrate the viability and tolerable overhead of our solution via an open-source prototype. 
Practical identity-based private sharing for online social networks