Identity Provider SSO vs. Service Provider SSO

Written by Kelsey Kinzer on February 6, 2023

Share This Article

Today’s employees use multiple applications every day and don’t have the time or mental space to memorize hundreds of passwords.

Enter: Single sign-on (or SSO). Single sign-on models enable users to connect to web apps, file sharing systems, and cloud servers with just one set of credentials, reducing their mental load and speeding up the login process. SSO is ideal for admins, too, increasing their visibility and control and shrinking their queue of help tickets.

But when organizations start thinking about implementing SSO, they’re likely to come across two methods — identity-initiated SSO and service provider-initiated SSO.

To ensure you pick the right SSO technique for your company, we’ll explain what each of those terms means, their pros and cons, and how they differ. 

What Is IdP-Initiated SSO?

In plain terms, identity provider-initiated single sign-on uses an identity-as-a-service provider (IdP) to validate an authenticated user’s access to an application.

Organizations use identity providers to store user credentials and authenticate users who attempt to access the company’s network. Many identity providers are OpenLDAP or Microsoft Active Directory implementations, or a cloud-based IdP like JumpCloud.

In IdP-initiated SSO, users navigate to the company’s identity provider and click on the application they want to access. 

In the background, the identity provider sends a SAML authentication request to the service provider to ensure the end user has the appropriate access privileges. If the provider accepts the SAML response, the user can log into the application and start their session.

What Is SP-Initiated SSO?

Service provider-initiated SSO flips this scenario — a service provider requests authentication from an identity provider to validate an authenticated user’s access to an application.

When a user wants to log into an application, the application redirects the request to the company’s identity provider. The identity provider confirms the user’s identity and access level and sends a SAML response and assertion to the service provider, allowing the user to log in.

What’s the Difference Between IdP-Initiated SSO and SP-Initiated SSO?

The main difference between IdP-initiated SSO and SP-initiated SSO is where users start the login process. IdP-initiated login requests start in the identity provider, whereas SP-initiated login requests start in the application users want to access.

An IdP-initiated login looks something like this:

  1. A user logs into the identity provider.
  2. The user clicks on the application they want to access in the IP catalog.
  3. The identity provider packages the user’s identity, pertinent information, and what the user can access into an XML-based SAML assertion.
  4. The identity provider sends a secure reference to the SAML assertion to the service provider or through the user’s browser.
  5. The service provider reviews the assertion and accepts the assertion as valid.
  6. The user is logged into the application and can begin their work.

An SP-initiated login looks something like this:

  1. An unauthenticated user goes to the login page of the application they want to use.
  2. The service provider redirects the user to the identity provider.
  3. The identity provider creates a SAML assertion and sends it to the service provider.
  4. The service provider accepts the assertion.
  5. The user is logged into the application and can begin their work.

There are pros and cons to both methods of SSO initiation.

Pros and Cons of IdP-Initiated SSO


  • IdP is highly flexible, so IT teams can configure it to fit their specific use cases.
  • Some service providers can’t issue SAML requests, making IdP a necessary solution.


  • IdP-initiated SSO is susceptible to man-in-the-middle attacks where the attacker either intercepts or steals the SAML assertion.
  • Sometimes, IdP-initiated SSO can overwrite existing sessions within a service provider.

Pros and Cons of SP-Initiated SSO


  • Users can initiate their login straight from the application they want to use, rather than having to log into an identity provider first.
  • Since the service provider redirects the request, SP-initiated SSO doesn’t typically cause session overwriting.


  • Some service providers can’t issue SAML requests.
  • SP-initiated SSO may be more challenging to troubleshoot if there is an error on the service provider’s end. 

Mitigating the Risk of SAML IdP-Initiated SSO

There are three main ways of reducing the risk of man-in-the-middle attacks with IdP-initiated SSO:

  1. Use minimum possible response trust length – Part of SAML assertion validation involves reviewing when packages expire and when they were issued. Therefore, IT teams should configure their IdP with the minimum length of time to trust responses to leave less time for interception.
  1. Leverage replay detection – Some cyberattackers attempt to reuse SAML assertions to gain access to company applications. Installing a replay detection platform can reduce the chances of unauthorized access. These tools assess whether an assertion has already been seen, preventing it from being reused.
  1. Follow the specification – SAML 2.0 specifications include a section regarding unsolicited responses that can safeguard companies from SAML theft. IT teams should ensure that service providers in their IdP-initiated SSO workflow do not accept unsolicited SAML responses with an InResponseTo value. 

While none of these methods are sufficient when used alone, implementing all three together minimizes the possibility of a detrimental attack.

Secure IdP-Initiated SSO with JumpCloud

It’s important to note that both methods of single sign-on involve the use of an identity provider. When storing sensitive information in a third-party authentication service, you run the risk of the IdP mishandling data or being the target of a cyberattack. 

That’s why it’s critical to work with an SSO provider that can help you layer on additional security controls and IAM capabilities. JumpCloud is an IdP for the modern enterprise, securely connecting users to resources regardless of location, platform, or provider. JumpCloud supports globally used applications like Salesforce, Atlassian, and Google Workspace, file storage providers like Google Drive and Dropbox, as well as major servers like GCP and AWS.

JumpCloud protects users on the back end while providing an easy-to-use front end, giving both your IT team and employees an ideal SSO experience.


See more of JumpCloud’s capabilities and its overall pricing structure.

Kelsey Kinzer

Kelsey is a passionate storyteller and Content Writer at JumpCloud. She is particularly inspired by the people who drive innovation in B2B tech. When away from her screen, you can find her climbing mountains and (unsuccessfully) trying to quit cold brew coffee.

Continue Learning with our Newsletter