Friendship Protection: A Trust-Based Shamir Secret Sharing Anti-collusion Attack Strategy for Friend Search Engines

Online social networks (OSNs) provide users with applications to interact with friends or strangers. Among these applications, the friend search engine allows users to query other users’ personal friend lists. However, if there is no suitable protection strategy, the application is likely to compromise the user’s privacy. Some researchers have proposed privacy protection schemes to protect users from attacks that are initiated by independent attackers, but few researchers have conducted research on collusion attacks initiated by multiple malicious requestors. In this paper, we propose a resistance strategy against collusion attacks that are initiated by multiple malicious requestors in OSNs, introduce trust metrics, and limit users’ ability to query through the Shamir secret sharing system (t, n) threshold function in the friend search engine to protect the user’s friendships from collusion attacks by multiple attackers. The effectiveness of the proposed anti-collusion attack strategy is verified via synthetic and realistic social network datasets. Research on collusion attack strategies will help us design a safer friend search engine for OSNs.