SP-Initiated SSO vs. IdP-Initiated SSO

Choosing between SP-initiated and IdP-initiated SSO isn’t just tech talk; the right choice can help to bolster your company’s security and productivity.

Market insights can be eye-opening. According to Fortune Business Insights, the global Single Sign-On (SSO) market is expected to grow as cybersecurity threats rise, making SSO a prime solution for organizations seeking to secure their systems.

In this article, we will be looking at which type of SSO solution (IdP-initiated or SP-initiated) can prove to be an ideal choice for your business. miniOrange offers SSO solutions that match your organization’s needs and align with the current market trends.

Basically, the bottom line is: the right SSO approach isn’t just smart, it is your ticket to the big leagues. If you fall behind, your competitors will sprint ahead.

What is Single Sign-On (SSO) Exactly?

Single Sign-On (SSO) is a security approach where users can gain access to multiple applications with just one set of credentials, enhancing convenience and security.

The users enter their credentials into an Identity Provider (IdP), and this IdP verifies the user credentials with those stored in a database like Active Directory. Once the credentials are confirmed, the user is granted access to the applications.

SSO operates on federated identity principles, sharing attributes across trusted systems using protocols like OpenID Connect (OIDC) and SAML 2.0. SSO has evolved since the 1990s, side-by-side with Lightweight Directory Access Protocol (LDAP) and Active Directory (AD), to meet the modern authentication needs.

What is an IdP-Initiated SSO?

An Identity Provider (IdP) is a trusted service that authenticates user identities and grants secure access to multiple applications. It centralizes the authentication process, boosting security and simplifying access management.

IdP-initiated SSO is a process where the user authentication request is initiated by IdPs such as Google Workspace, Okta, Microsoft Entra ID, or AWS. In simple terms, the IdP is the starting point for the user’s login journey.

What is SP-Initiated SSO?

In Identity and Access Management (IAM), a Service Provider (SP) can be a website, app, or service that a user wishes to access.

A SP depends on a trusted IdP for user authentication, and once an IdP confirms the user’s identity, the SP grants access to the resources to the users. Examples of service providers are project management tools, social handles, cloud-based apps, and more.

SP-initiated SSO is a process where the authentication request is initiated by the Service Provider (SPs).

How is IdP-Initiated Different from SP-Initiated SSO?

IdP SSO differs from SP-initiated SSO in various ways, from login flow to use cases. Let’s understand the difference in-depth.

Pros and Cons of IdP-Initiated SSO

Here’s a consolidated list of the benefits and drawbacks of using IdP-initiated SSO.

Pros

• Simple for users, as everything is centralized in one place.
• IdP is flexible, so it can be configured with multiple SPs to fit specific use cases.
• IdP-initiated login can be integrated with authentication solutions, such as passwordless, biometrics, 2FA, adaptive MFA, and more, exclusively offered by miniOrange.

Cons

• Vulnerable to the Man-in-the-Middle Attacks, where cybercriminals hamper SAML assertions.
• In case the login message is intercepted, then someone else (a harmful entity) can pretend to be the user.

Pros and Cons of SP-Initiated SSO

Here’s a brief outlook on the advantages and disadvantages of SP-initiated SSO.

Pros

• Users can log in straight from the app they want to use, instead of logging in from an IdP.
• There’s no session rewriting as SP-initiated SSO redirects requests to the IdP.

Cons

• Some SPs are not suitable for SAML requests, and these are Single-Page Applications (SPA), APIs, or consumer-facing apps.
• Difficult to troubleshoot if there’s an issue at the SP’s end.

IdP-Initiated SSO Workflow

In the IdP-initiated workflow, the user tries to log into an IdP like Google Workspace and then access their desired application or resources. Here’s how the workflow works:

1. User Authentication at IdP

• The user visits the IdP portal and logs in with credentials.
• The IdP verifies the identity against its database (AD or LDAP).

2. SAML Token Creation

• IdP generates a signed SAML assertion containing the user’s authentication information.
• This assertion includes the necessary user attributes for the SP.

3. Token Transmission

• IdP packages the assertion into an SAML response.
• The IdP sends a digitally signed response to the SP via HTTP POST.

4. SP Verification

• SP receives a SAML response.
• The service provider validates the IdP’s digital signature.
• Extraction and verification of SAML assertion by SP.

5. Access Authorization

• The SP checks the user’s permissions against access policies.
• Then the service provider grants access to the requested service if the validation is successful.

This workflow assures a smooth and secure login experience, reducing the need for multiple logins across different services.

SP-Initiated SSO Workflow

The SP-initiated SSO begins at the application the user wants to access, and the workflow is as follows:

1. Initial SP Access and Redirect

• The user tries to access the SP.
• The SP redirects an unauthenticated user to an IdP, along with a SAML request.

2. User Authentication

• The user arrives on the IdP login page.
• Credentials for verification are provided by the user.
• The IdP validates the credentials against the user database.

3. SAML Token Generation and Packaging

• The IdP creates a SAML assertion with the user’s authentication information.
• It then packages the assertion into a signed SAML response.
• The IdP also includes essential attributes for SP.

4. Token Transmission and Receipt

• IdP sends a signed SAML response to the SP via an HTTP Post.
• The SP receives it and then extracts the SAML assertion.
• IdP’s digital signature is verified by the SP.

5. Validation and Authorization

• The SP validates the SAML assertion against access policies.
• It checks the user’s permissions and roles.
• It grants access to the requested service if the user is verified; otherwise, the entry is denied.

This workflow can be a bit complex due to the initial redirection, but it is one of the go-to options for users logging directly into the specific applications.

Practical Use Cases of IdP and SP-Initiated SSO

Here’s a consolidated list of the areas where IdP-initiated and SP-initiated SSO can be implemented.

IdP-Initiated SSO Use Cases

IdP SSO finds its uses across four different industries, which are as follows:

• Corporate: Assure easy access to various internal and external apps/resources.
• Education: Seamless access to Learning Management Systems (LMS), such as Moodle, Coursera, Udemy, Blackboard, and more.
• Healthcare: Quick and secure access to patient portals, healthcare apps, and wellness applications.
• E-Commerce: Use a single ID to shop across multiple e-commerce platforms such as Shopify, Amazon, or Walmart.

SP-Initiated SSO Use Cases

SP-initiated SSO can be used for the following purposes:

• Federated Identity Scenarios: It is used for federated SSO, where the SP’s ability to check the user’s intent to access the apps makes it more secure.
• Customer-Facing Applications: Consumer-facing apps such as healthcare portals, banking, and e-commerce, where customers log in directly.
• Public-Facing Apps: Apps that the users access from various organizations, so they can log in directly and authenticate themselves with their organization’s IdP.

SP-Initiated vs. IdP-Initiated SSO: Which One to Choose?

IdP vs. SP, both of them differ from each other in a lot of ways. You can choose SP-initiated SSO when there’s a need to control the login process, and for consumer-facing applications. It also works best for environments demanding granular security, better audit trails, and compatibility with various IdPs.

IdP-initiated login works best for tightly controlled business organizations, centralized access scenes, and legacy software integrations.

How Can miniOrange Help?

miniOrange offers comprehensive SSO solutions, including SP-initiated, IdP-initiated, and Federated SSO to cater to the diverse authentication needs. miniOrange SSO solutions also support OAuth, JWT, and OpenID Connect protocols, and allow seamless integration with various applications.

Strengthen your organization’s defences with a product that supports both user experience and security. Also, avail additional features such as Multi-Factor Authentication (MFA) software, Risk-Based Authentication (RBA), phishing-resistant MFA, and more.

Connect with us today for a free SSO trial, and check out our flexible pricing options.

FAQs

When to use both IdP- and SP-initiated SSO?

Make use of IdP-initiated SSO when the authentication starts at the IdP login page, and use SP-initiated SSO when the users wish to grant access to an app directly.

How to mitigate the risk of SAML IdP-Initiated SSO?

Make sure that SAML assertions are validated and signed to prevent tampering, and allow assertions only for specific SPs. Further, use MFA to solidify security during logins, and allow SSO only from trusted IdPs to prevent unauthorized access. You can constantly track login attempts and anomalies for quick incident response. Also, set expiration times for SAML tokens to avoid session hijacking.

What is Identity Federation?

Identity federation is a process of establishing trust between various organizations to allow users to access across various apps with just one set of credentials.