SAML 2.0

SAML 2.0 (Security Assertion Markup Language) is the XML-based federation standard behind single sign-on for DigiD, eHerkenning, and eIDAS nodes.

SAML 2.0 (Security Assertion Markup Language) is the XML-based federation standard, published by OASIS in 2005, that predates OpenID Connect: the identity provider issues a digitally signed XML assertion about the authenticated user, which travels via the user's browser (typically using the HTTP-POST or HTTP-Redirect binding) to the service provider. It remains the backbone of much enterprise and government SSO - DigiD and eHerkenning connections are classic SAML territory, and the eIDAS network of cross-border national nodes also relies on a SAML 2.0 profile for interoperability, unlike the EUDI Wallet, which uses OpenID4VC.

SAML's signed-XML machinery is powerful but heavy; new integrations usually prefer OIDC, while existing federations keep running SAML for years. Functionally they solve the same problem with different plumbing. SAML addresses authentication and attribute federation, not API authorization delegation - that is the role of OAuth 2.0, with which it is often confused.