Online Social Networks (OSNs) are quite popular platforms that have an environment where a person can contact to another person without restricting their locations. Users get in contact with each other via sharing contents of data such as videos, photos, messages, and events. Shared contents do not include always only the user's information, who uploads the content to OSNs, but also include other users' information. This type of data sharing might cause serious problems on other people's lives, the type of content is called co-owned data. Current OSNs do not have systems in which there is an enforcement system to make a balance between co-owned data sharing and protection of users' privacy. One way to make the balance is to use reputation systems on co-owned data sharing process in which OSNs' users could be punished or awarded based on their own actions on the co-owned data sharing process. In this work, we propose a reputation system where trust values, which exist between OSNs' users, are used as feedback values. The beta reputation system is used as a groundwork to develop the proposed work's models.