This paper presents Musubi, a mobile social application platform that enables users to share any data type in real-time feeds created by any application on the phone. Musubi is unique in providing a disintermediated service to end users; all communication is supported using public key encryption thus leaking no user information to a third party. Despite the heavy use of cryptography to provide user authentication and access control, users found Musubi simple to use. We embed key exchange within familiar friending actions, and allow users to interact with any friend in their address books without requiring them to join a common network a priori. Our feed abstraction allows users to easily exercise access control. All data reside on the phone, granting users the freedom to apply applications of their choice.