Federated identity

A federated identity in information technology is the means of linking a person's electronic identity and attributes, stored across multiple distinct identity management systems.

Federated identity is related to single sign-on (SSO), in which a user's single authentication ticket, or token, is trusted across multiple IT systems or even organizations. SSO is a subset of federated identity management, as it relates only to authentication and is understood on the level of technical interoperability, and it would not be possible without some sort of federation.

In information technology (IT), federated identity management (FIdM) amounts to having a common set of policies, practices and protocols in place to manage the identity and trust into IT users and devices across organizations.

Single sign-on (SSO) systems allow a single user authentication process across multiple IT systems or even organizations. SSO is a subset of federated identity management, as it relates only to authentication and technical interoperability.

Centralized identity management solutions were created to help deal with user and data security where the user and the systems they accessed were within the same network – or at least the same "domain of control". Increasingly, however, users are accessing external systems which are fundamentally outside their domain of control, and external users are accessing internal systems. The increasingly common separation of the user from the systems requiring access is an inevitable by-product of the decentralization brought about by the integration of the Internet into every aspect of both personal and business life. Evolving identity management challenges, and especially the challenges associated with cross-company, cross-domain access, have given rise to a new approach to identity management, known now as "federated identity management".

FIdM, or the "federation" of identity, describes the technologies, standards and use-cases which serve to enable the portability of identity information across otherwise autonomous security domains. The ultimate goal of identity federation is to enable users of one domain to securely access data or systems of another domain seamlessly, and without the need for completely redundant user administration. Identity federation comes in many flavors, including "user-controlled" or "user-centric" scenarios, as well as enterprise-controlled or business-to-business scenarios.

Federation is enabled through the use of open industry standards and/or openly published specifications, such that multiple parties can achieve interoperability for common use-cases. Typical use-cases involve things such as cross-domain, web-based single sign-on, cross-domain user account provisioning, cross-domain entitlement management and cross-domain user attribute exchange.

Use of identity federation standards can reduce cost by eliminating the need to scale one-off or proprietary solutions. It can increase security and lower risk by enabling an organization to identify and authenticate a user once, and then use that identity information across multiple systems, including external partner websites. It can improve privacy compliance by allowing the user to control what information is shared, or by limiting the amount of information shared. And lastly, it can drastically improve the end-user experience by eliminating the need for new account registration through automatic "federated provisioning" or the need to redundantly login through cross-domain single sign-on.