Nowadays the computing mobile devices around us are becoming powerful and user-friendly. Cost-efficient wireless access technologies have lately changed the landscape for smart home environments to a large extent. Developments in the media landscape with large flat screens, new capturing devices, and large digital media libraries have also changed the way smart home environments are used. This thesis presents and evaluates architecture for multimedia sharing in such environments. Using this architecture, an end-user can gain access to various types of media resources available at his/her home while roaming to other people’s home network. In this architecture the user’s mobile device is used for authenticating with a network node like home gateway in the home or visited environment using the infrastructure provided by the operator. The multimedia sharing system is implemented using home gateways and OSGi framework. For media sharing an http-based proxy mechanism is proposed and developed. Also an AAA server is used for user authentication, accounting, and authorization. Furthermore, a performance study on authentication and media transferring of the proposed system was included. In conclusion the thesis shows a process of secure multimedia sharing among homes using operators' existing infrastructures.