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The goal of supporting Single Sign-On to the Web has proven elusive. A number of solutions have been proposed -- and some have even been deployed -- but the capability remains unavailable to most users and the solutions deployed raise concerns for both convenience and security. In this paper, we enumerate desirable attributes in a scheme for authenticating from an Internet browser to a web site and the authorization that follows. We categorize the currently deployed or advocated approaches, describing their benefits and issues, and we suggest incremental improvements to such schemes. We then outline a design for public-key based authentication particularly suited to what we believe to be the common case: users, acting on their own behalf (as opposed to as an employee of an organization), performing actions on the web such as making a purchase or maintaining an account at a service provider. We contrast the usability/privacy/security properties of our design with other identity management/authentication schemes deployed or being proposed today. Our design is truly user-centric, in the sense that the user acts as his own CA, and as a decision point for authorizing release of user information to web sites, rather than having an Identity Provider be the center of trust.