What is SAML (Security Assertion Markup Language)? [2023]

SAML (Security Assertion Markup Language) is an XML-based open standard used for exchanging authentication and authorization data between identity providers (IdPs) and service providers (SPs). It enables secure single sign-on (SSO) authentication across different systems, domains, and organizations.

The SAML protocol consists of three main components: the identity provider, the service provider, and the user or principal. The identity provider is responsible for authenticating the user and generating SAML assertions, which are XML documents containing authentication and authorization information. The service provider is the system or application that the user wants to access. The user is the individual seeking access to the service.

When a user attempts to access a service provided by an SP, the SP redirects the user to the IdP for authentication. The IdP verifies the user's identity and generates a SAML assertion containing the necessary user attributes, such as their identity, roles, or access privileges. This assertion is then digitally signed by the IdP to ensure its integrity.

The user is redirected back to the SP with the SAML assertion, which is presented as proof of authentication. The SP verifies the digital signature and validates the assertions, allowing the user to access the requested service without needing to provide credentials again. This process eliminates the need for users to remember multiple usernames and passwords for different applications, enhancing convenience and user experience.

SAML supports different authentication scenarios, including web-based SSO, where the user logs in once and gains access to multiple applications, and federated SSO, where authentication is extended across multiple organizations or domains. It also supports attribute-based access control, allowing the IdP to provide information about the user's roles, group membership, or other attributes to inform access decisions by the SP.

SAML is widely used in enterprise and web-based applications for secure identity federation and SSO. It provides a standardized and interoperable approach to authentication and authorization, enhancing security and simplifying user access management across heterogeneous systems and environments.