Systems and methods may be provided for masking data on public networks, such as social networking sites. At a publishing node, the system may monitor data input fields in a webpage, and intercept and encode content, such as text, images, and video input at the data input fields, prior to the content being posted online on a public service provider's website. A privacy agent may process input field content to try to detect encoding markers in the input field content, which define portions of the content that are to be encoded. A third party key server may be used to store decoding keys. A URI reference to the decoding key may be used to access the decoding key by a node attempting to view the decoded version of the input field content.