A statement that a user is authenticated and authorized to access a resource.
Description
In the context of Single Sign-On (SSO) protocols, an assertion is a package of information that is sent from an Identity Provider (IdP) to a Service Provider (SP) to confirm a user's identity and permissions. When a user logs in through an SSO system, the IdP generates an assertion, which typically includes details such as the user's identity, attributes, and the conditions under which the assertion is valid. This assertion is then presented to the SP, allowing the user to access various applications without needing to log in multiple times. Assertions can come in various formats, including SAML (Security Assertion Markup Language) and JWT (JSON Web Token). For instance, when a user logs into Google, Google acts as the IdP, creating an assertion for the user's identity that can be used to access other services like Gmail or Google Drive seamlessly. The use of assertions in SSO enhances user convenience and improves security by reducing the number of times users need to enter their credentials.
Examples
- A SAML assertion used by a corporate intranet to grant employees access to internal tools after logging in through an IdP.
- A JWT assertion that allows users to access multiple third-party applications after authenticating with a service like Auth0.
Additional Information
- Assertions are time-sensitive and typically include expiration times to enhance security.
- They can carry various user attributes, such as roles and permissions, which help SPs make access control decisions.