What authentication feature does Security Assertion Markup Language (SAML) provide?

The Security Assertion Markup Language (SAML) primarily provides the feature of using digital signatures to establish trust between the identity provider and the service provider. Digital signatures in SAML ensure that the assertions—a set of statements regarding a subject (such as a user)—are authentic and have not been tampered with during transmission. By utilizing digital signatures, SAML guarantees the integrity of the asserted data and the legitimacy of the identity provider, making it possible for service providers to rely on the assertions being true.

This authentication mechanism is crucial in single sign-on (SSO) environments where users may traverse various services seamlessly without needing to authenticate multiple times. The digital signatures facilitate secure communication between different domains and applications, ensuring that user identities are accurately verified while minimizing the risk of impersonation and fraudulent activities. The use of digital signatures thus enhances the overall security posture of SAML implementations by allowing downstream systems to verify that the assertions are both unaltered and legitimate.