In this single sign-on (SSO) scenario, the service provider (SP) sends an authentication request to the identity provider (IdP) through HTTP POST. The returned SAML assertion redirects through the user's browser, and the response contains a SAML artifact.
- A user requests access to a protected SP resource. The user is not logged on to the site. The request redirects to the federation server to handle authentication.
- The federation server sends an HTML form back to the browser with a SAML request for authentication from the IdP. The HTML form automatically posts to the IdP's SSO service.
- If the user is not already logged on to the IdP site or needs to re-authenticate, The IdP asks for credentials, such as ID and password, and the user logs on.
- The user data store can provide additional information about the user for inclusion in the SAML response. The federation agreement between the IdP and the SP predetermines these attributes. See User attributes.
- The IdP federation server generates an assertion, creates an artifact, and sends an HTTP redirect containing the artifact through the browser to the SP's Assertion Consumer Service (ACS).
- The ACS extracts the source ID from the SAML artifact and sends an artifact-resolve message to the federation server's Artifact Resolution Service (ARS).
- The ARS sends a SAML artifact response message containing the previously-generated assertion.
- (Not shown) If the IdP returns a valid SAML assertion to the SP, a session is established on the SP and the browser is redirected to the target resource.