BASH script to run a SAML flow with cURL against the SSOCircle IDP (IDP) and the Fedlet Test SAML service provider (SP).

CLIENT accesses the SP (Initiate the SSO flow – this is typically a “sign in” button or simply a request to a protected page)
SP replies with a SAML AuthnRequest message (typically a 302 redirect to the IDP)
CLIENT follows the redirect and sends the SAML AuthnRequest message to IDP
If user is not already authenticated with the IDP
a. IDP redirects to the IDP login page
b. CLIENT submits credentials vial the login form to IDP
c. IDP authenticates the user and redirects the user to continue with SSO
IDP generates the SAML Response with the Assertion and sends it back to the CLIENT (typically this is a HTML page with an auto-posted form)
SKIPPED (will be implemented in Part II)
SKIPPED (will be implemented in Part II)
CLIENT continues posting the SAML Response message to the SP
SP receives the SAML Response message and authenticates the user based on the Assertion (if SSO is successful the SP typically replies with a “logged in” page or the protected content)
CLIENT receives the SP response and evaluates if the SSO flow was successful (user is logged in)