Single Sign-On (SSO) allows users to log in once and access multiple applications without repeated authentication. However, not all SSO flows work the same way, case in point - idP vs. SP initiated SSO.
These are the two main types of SSO that exist: IdP-Initiated SSO and SP-Initiated SSO. And while they serve a similar purpose, the way authentication is handled differs. So we’ll help make this a little easier to understand.
What Is IdP-Initiated SSO?
IdP-Initiated SSO or Single Sign On begins at the Identity Provider (IdP). The user first logs into the IdP, sending an authentication assertion to the Service Provider (SP) to allow access.
To do this, you navigate the page or domain provided by the identity provider, authenticate yourself, and then navigate to whatever tools you would want to use.
This is one of the more ideal SSO solutions for companies and enterprises that want centralized access and control to their tools and the conditions under which users have access to them.
IdP-Initiated SSO Workflow
- Step 1: The user would navigate to the IdP provided page for their company, the IDP in the case would be software like Infisign, Okta, or Microsoft Entra ID.
- Step 2: The IdP verifies the user's identity by using an authentication system like MFA or passwordless authentication.
- Step 3: The IdP generates a security assertion once the user is authenticated.
- Step 4: The user selects an application from the IdP’s dashboard.
- Step 5: The IdP sends the assertion to the SP.
- Step 6: The SP accepts the assertion and allows access.
Pros of IdP-Initiated SSO:
- Allows a login experience from a central portal.
- Reduces password fatigue and improves productivity.
- Works well in enterprise environments with multiple connected applications.
Cons of IdP-Initiated SSO:
- Less secure since users can be redirected without explicit authentication requests.
- Prone to session hijacking if not properly secured.
- Limited visibility into authentication requests for some service providers.
What Is SP-Initiated SSO?
SP-Initiated SSO starts when a user tries to access an application directly. The SP redirects the user to the IdP for authentication and then allows access.
In the case of this type of authentication, your company might have a number of tools that need additional authentication to log in to.
For instance, if you were to log in to your company’s Salesforce account and they have an IdP like Infisign or Entra ID, this would redirect you there and then grant access after you authenticate your identity with your IdP.
SP-Initiated SSO Workflow
- Step 1: The user attempts to log into the SP directly, this can be a software like Salesforce or even Hubspot.
- Step 2: Once you do this, the SP detects no active session and redirects the user to the IdP.
- Step 3: So to log you in, the IdP prompts the user to log in (if not already authenticated).
- Step 4: After this, the IdP verifies the user’s identity and sends an assertion to the SP.
- Step 5: Finally, the SP validates the assertion and allows access - the app for a specific timeframe based on the setting your company admin puts in place with your IdP.
Pros of SP-Initiated SSO:
- More secure since authentication is explicitly initiated by the SP.
- Better logging and visibility into authentication requests.
- Reduces unauthorized access risks compared to IdP-Initiated SSO.
Cons of SP-Initiated SSO:
- Requires an additional redirect, slightly increasing login time.
- Can be complex to configure across multiple service providers.
- It relies on the SP to correctly handle authentication requests.
IdP-Initiated SSO vs SP-Initiated SSO: Key Differences
Authentication Flow
- IdP-Initiated SSO starts from the IdP, while SP-Initiated SSO starts at the service provider.
- Or put in simple terms, when you try to login to the device, in the case of SP initiated SSO you go to the app, and the app redirects you to its SSO authentication system.
- For IdP initiated SSO, you first need to log in to the IdP platform, which then authenticates you on various different applications as needed.
Security Considerations
- In terms of security with IdP vs.SP-initated SSO, SP-Initiated SSO is generally more secure since the authentication request originates from the application itself.
- Also, in the case of IdP initiated SSO, they are more susceptible to session hijacking and relay attacks. But again, if your IdP has risk-based authentication and MFA, this will likely not be a problem at all.
- Both can be equally secure granted that there are advanced authentication systems in place like adaptive MFA, brute force protection, and risk-based access.
User Experience
IdP-Initiated SSO allows users to launch applications directly from a central portal.
- In this case IdP is a lot quicker to use - this allows users access to multiple applications from one dashboard.
- In the case of SP-initiated, since you go directly to the app, it definitely takes a little more time. However, it’s more secure for companies trying to avoid any miniscule chance of relay attacks or session hijacking.
When to use IdP initiated SSO vs SP initiated SSO
So the burning question is iDP vs. SP initiated SSO - which is better? The answer is that it depends entirely on your company, its tech stack, and its security needs.
IdP-Initiated SSO is useful for companies with multiple connected applications where users access software from a single dashboard.
However, SP-Initiated SSO is ideal when security is a priority, as it keeps authentication requests within the SP environment.
How to Set Up IdP and SP-Initiated SSO Without Security Risks
- Use encrypted authentication assertions: Using encrypted authentication assertions like SAML helps make sure that your tech stack and company data remains safe. In the case of tools that use OAuth pairing, this OIDC helps make sure additional non-sensitive user information is shared during authentication.
- Apply Multi-Factor Authentication (MFA) for added security: When you pair your SSO with an adaptive MFA framework in place, you make sure that it is an additional authentication proof that varies based on risk factors.
- Regularly review authentication logs to detect anomalies: IT admins need to set systems in place that allow them to review access logs to monitor for any odd access requests. Most IAM or CIAM software comes with these capabilities built in, and many even use AI to flag for unusual behaviour.
- Apply strict session timeout policies: Session timeout policies are a major aspect in making sure that unauthorized access is not a possibility. With your IdP admins and access policies need to be limited to specific periods and restricted based on inactivity.
How Infisign Supports SP-Initiated and IdP-Initiated SSO for Enterprises
IAM software like Infisign’s IAM Suite works with both IdP and SP-Initiated SSO, allowing zero-trust authentication with strong security measures.
With adaptive MFA, real-time access control, and API connections, Infisign helps businesses manage identities while keeping data safe. Also, it also supports non-SSO compatible web-based or legacy software.
Here are some of the major reasons you should consider Infisign:
- AI Access Assist: Infisign comes with AI-powered access management with AI interfaces that provision users based on existing policies, raising requests on platforms like Slack and Teams. It also can handle non-human identity authentication for complete security.
- Adaptive MFA: Adaptive MFA in Infisign makes sure that users are granted access after 2 or more authentications. The authentications required vary based on authentication-risk levels. This allows the use of biometrics, device passkeys, OTPs (email+SMS), push-notifications and even QR codes.
- 6000+ API + SDK Integrations: With more than 6000+ app integrations, Infisign is an Identity provider that is easy to implement with your existing tech stack. This is also helpful for growing companies still expanding the scope of the tools and operations.
- Automated User Provisioning: With user authentication that is automated, user-lifecycle management becomes a lot easier and can be done quicker with the usage of role-based access and attribute-based access control for thousands of users in one go.
- Universal Single-Sign On: Infisign allows users to log in to multiple applications in one go. For legacy and web-based applications, it comes with MPWA that enables the functionality of SSO on these without revealing the actual password to users.
- MPWA: Managed Password Authentication a system in Infisign that allows users to login to a web-based application that does not support SSO protocols.
- Network Access Gateway: Enable secure cloud access for on-premises applications using Infisign through the usage of network access gateways or NAG.
- Unlimited Directory Sync: Although most IAM or CIAM software require additional subscriptions or costs for directory synchronization, Infisign allows this functionality as many times as needed without any hidden costs.
Add Infisign’s SSO to Your Techstack in Under 4 Hours
Infisign’s deep integrations with 6000+ applications make adding it to your tech stack surprisingly quick - in under 4 hours. Aside from this, you can use it alongside your existing access management tools and security software.
SSO is an incredible tool when it comes to reducing user dropoffs and improving employee productivity. And with AI-access assist, MPWA and NAG access management Infisign makes access management all-encompassing.
Looking to simplify SSO for your business? Try Infisign today.
