What Is Single Sign-On and How Does It Work?

Managing separate usernames and passwords for every business application can quickly become frustrating. This is where Single Sign-On (SSO) can help. SSO allows users to authenticate once and access multiple connected applications without repeatedly entering their login credentials.

What Is Single Sign-On?

Single Sign-On is an authentication method that allows one login to provide access to multiple applications and services.

Instead of maintaining a separate password for every platform, users authenticate through a trusted Identity Provider (IdP). Once their identity is verified, connected applications can recognize that authentication and provide access based on the user's permissions.

For example, an employee could sign in using their company account and then access business applications such as Microsoft 365, Salesforce, Slack, or internal systems without completing a separate login for each service.

The important point is that SSO simplifies authentication, but it does not automatically determine what a user can access. Individual applications still control authorization and permissions.

How Does SSO Work?

A typical SSO process involves the user, an application, and an identity provider.

The process generally works like this:

1. The user opens an application that supports SSO.

2. The application redirects the user to the configured identity provider.

3. The user authenticates using a password, MFA, security key, or another supported method.

4. The identity provider verifies the user's identity.

5. The identity provider sends an authentication response to the application.

6. The application validates the response and creates a session for the user.

After this process, the user can access the application according to their assigned permissions.

If another connected application uses the same identity provider, the user may not have to authenticate again while their identity-provider session remains active.

Common SSO Protocols

SSO can be implemented using different protocols depending on the application's technology and requirements.

SAML is widely used for enterprise applications and web-based business services. It allows an identity provider to send an authentication assertion to a service provider.

OpenID Connect (OIDC) is commonly used with modern web and mobile applications. It is built on OAuth 2.0 and provides a way for applications to verify a user's identity.

OAuth 2.0 is primarily used for authorization. It allows applications to access protected resources without requiring users to provide their credentials directly.

Kerberos is a ticket-based authentication protocol commonly found in enterprise networks and Active Directory environments.

Although these technologies are often discussed together, they do not all serve exactly the same purpose. The right choice depends on the application's architecture and integration requirements.

Benefits of Single Sign-On

SSO can provide practical benefits for both users and IT teams.

Better User Experience

Users have fewer passwords to remember and fewer login screens to work through when accessing connected applications.

Centralized Access Management

IT teams can manage authentication policies through a central identity provider instead of maintaining independent authentication systems for every application.

Easier Onboarding and Offboarding

Centralized identity and group management can make it easier to provide access when employees join an organization and remove access when they leave.

Support for Stronger Security

SSO can work alongside security controls such as Multi-Factor Authentication, conditional access policies, monitoring, and least-privilege access.

Is SSO Secure?

SSO can improve security, but its effectiveness depends on how it is configured and managed.

Because authentication is centralized, protecting the identity provider is particularly important. A compromised identity-provider account could potentially provide access to multiple connected applications.

Organizations should use MFA, regularly review permissions, monitor authentication activity, maintain certificates and configuration data, and remove access promptly when users leave.

SSO applications should also be tested after configuration changes to identify problems with redirects, attributes, group assignments, or permissions.

SSO and B2B Ecommerce

SSO is useful beyond internal employee applications. It can also support B2B ecommerce customers, dealers, distributors, and partners.

For example, a manufacturer may operate an ecommerce storefront, dealer portal, CRM, and partner platform. Without SSO, users may need different credentials for each system.

With SSO, an authorized user can authenticate through their organization's identity provider and access connected systems without repeatedly signing in.

This can be particularly useful for businesses operating multiple storefronts or digital portals for different regions, brands, customer groups, or partners.

However, authentication and authorization remain separate. SSO confirms the user's identity, while the ecommerce application determines whether that user can view specific catalogs, pricing, orders, accounts, or other resources.

SSO Is More Than a Login Feature

Single Sign-On can simplify application access while giving organizations greater control over authentication. But successful implementation requires more than connecting an application to an identity provider.

Businesses need to consider the appropriate protocol, application compatibility, user and group mapping, provisioning, permissions, MFA, monitoring, and security policies.

When these elements are planned properly, SSO can provide a smoother authentication experience for users while supporting centralized identity management across enterprise applications and B2B ecommerce environments.