The ever increasing proliferation of mobile devices has led to unprecedented concern on privacy infringement, and various security threat and privacy leakage emerged from the water in the last few years. Although the rich functionality has allowed users to store personal information and interact with privacy sensitive applications on the devices, it makes them the hot target inevitably for adversaries. Aside from providing local application and storage, the online photo and video sharing and displaying service have also triggered an outcry of concerns about privacy and copyright from the public, especially with new features of automatic tagging and facial recognition. Modern mobile devices usually lock themselves to prevent unauthorized users to access the privacy information stored locally, online social networks use techniques to conceal people’s privacy online, such as blurring, masking, and denaturing, or adding hidden watermark into the media to claim the ownership of the digital properties. In this research, I will mainly focus on analyzing the privacy issue in both local and online activities, propose frameworks for preventing information being compromised by attackers and unauthorized users, protocol and prototype for creating a healthy online photo and video sharing ecosystem in long run.