OpenID is a lightweight, easy to implement and deploy approach to Single Sign-On (SSO) and Identity Management (IdM), and has great potential for large scale user adoption especially for mobile applications. At the same time, Mobile Network Operators are increasingly interested in leveraging their existing infrastructure and assets for SSO and IdM. In this paper, we present the concept of Smart OpenID, an enhancement to OpenID which moves part of the OpenID authentication server functionality to the smart card of the user’s device. This seamless, OpenID-conformant protocol allows for scaling security properties, and generally improves the security of OpenID by avoiding the need to send user credentials over the Internet and thus avoid phishing attacks. We also describe our implementation of the Smart OpenID protocol based on an Android phone, which interacts with OpenID-enabled web services.