  We perform a comprehensive analysis and comparison of 14 web single sign-on
(SSO) systems proposed and/or deployed over the last decade, including
federated identity and credential/password management schemes. We identify
common design properties and use them to develop a taxonomy for SSO schemes,
highlighting the associated trade-offs in benefits (positive attributes)
offered. We develop a framework to evaluate the schemes, in which we identify
14 security, usability, deployability, and privacy benefits. We also discuss
how differences in priorities between users, service providers (SPs), and
identity providers (IdPs) impact the design and deployment of SSO schemes.
