What Is Single Sign-On (SSO)?
Single sign-on (SSO) is a user authentication method that allows users to access multiple related applications and services with a single set of login credentials. Instead of creating and remembering separate usernames and passwords for each service, the user is required to log in only once and then gain access to all connected applications.
Besides improving and simplifying the login experience for the user, SSO is also beneficial to organizations. It’s an easy, affordable and secure way to maintain control over access to applications and services.
How does SSO authentication work?
It’s important to note that the SSO authentication process may vary depending on the SSO protocol (which we’ll talk about later) and the services that need protection.
But as a rule of thumb, SSO works by creating a central repository of user credentials and a secure protocol for communication between the user, the applications, and the repository. The user logs in to a single entry point, which verifies their credentials and then provides access to all the connected applications.
SSO can be implemented in different ways, but the most common approach is using identity providers (IdP). An IdP is an entity that authenticates users and authorizes their access to multiple applications.
Once a user logs in to the IdP, the user's identity is verified, and a token is generated that represents the user's session. This token is passed along with each request the user makes to a connected application, and the application uses it to verify the user's identity without requiring additional authentication.
Here’s a breakdown of the process:
User authentication: When a user tries to access an application or service that is protected by SSO, they are redirected to the SSO provider's login page. The user then enters their login credentials.
Verification of credentials: The SSO provider then verifies the user's credentials against its user database to ensure that the user is who they claim to be. If valid, it generates a token containing information about the user's identity.
Token distribution: The SSO provider sends the token to the user's browser, which then forwards it to the service that the user is trying to access.
Token validation: The service then validates the token to ensure that a trusted SSO provider issued it and has not been tampered with. If the token is valid, the user is granted access.
Subsequent access: Next time the user wants to access the service, the browser sends the token directly, bypassing the need for the user to enter their login credentials again.
Logout: When the user logs out of the SSO provider, the token is invalidated, and they can no longer access the protected services without re-entering their login credentials again.
SSO vs Password Managers
While both SSO and password managers aim to simplify the login experience for users, they work differently. We’ve already explained how SSO works, so to understand the difference between the two solutions, here’s a brief overview of how password managers like LastPass or 1Password work:
Password storage: The user stores all of their login credentials in the password manager, which is protected by a single master password.
Password generation: Many password managers include a password generator tool that can create strong, unique passwords for each of the user's online accounts.
Autofill: When the user visits a website that requires a login, the password manager automatically fills in the login credentials for the user.
The main difference between SSO and password managers is that password managers do not reduce the number of passwords users need to access applications. They make it more convenient for users to authenticate by auto-filling credentials, and they marginally improve security through auto-generated strong passwords. However, as recent password manager breaches have shown, the best password is often no password.
SSO, on the other hand, ensures that users only need one set of credentials – that of the IdP – to access a host of applications.
Examples of SSO authentication
SSO is widely used across the public and private sectors in industries like finance, retail and tech:
Enterprises: Large corporations use SSO to provide their employees with easy access to a wide range of internal applications and services, such as email, HR systems, CMS, and project management tools.
Educational Institutions: Universities and schools use SSO to provide students with access to their course materials, library resources, and other online services.
Healthcare Organizations: Hospitals and healthcare providers use SSO to provide their staff with secure, HIPAA-compliant access to electronic medical records, scheduling systems, and other critical applications.
Government Agencies: Some government agencies use SSO to provide citizens or employees with secure access to databases and other online systems, such as license renewals and tax returns.
How secure is SSO?
SSO is widely considered to be a secure and convenient authentication method. But like any technology, it comes with some risks and limitations.
Centralized identity management: This helps reduce the risk of identity-related security breaches, as well as make it easier to track and monitor user activity.
Extra layer of security: It’s easier for organizations to enforce strong password policies and multi-factor authentication.
Single point of failure: If an attacker gains access to a user's SSO credentials, they can gain access to all of the user's accounts.
Dependency on the SSO provider: If the SSO provider experiences a security breach or is unavailable, users may be unable to access their accounts.
There are many SSO protocols available, but here are a few of the ones with wide adoption:
SAML (Security Assertion Markup Language):SAML is a widely-used open-source XML standard for exchanging identity data between an IdP and service providers (SP). It’s mostly adopted by enterprises.
OAuth 2.0 (Open Authorization): As the name suggests, OAuth is designed for authorization instead of authentication. Unlike SAML, it uses JSON instead of XML. Supported by popular IdPs like Google and Facebook, it’s best used for consumer-facing mobile and website applications.
OIDC (OpenID Connect): OpenID Connect is another open standard that runs on top of OAuth, providing authentication.
ADFS (Active Directory Federation Services): ADFS is a Microsoft-specific solution for SSO, mostly adopted by organizations that use Microsoft technologies.
Each of these SSO protocols has its own unique features, benefits and drawbacks. So the best choice for an organization depends on its specific requirements and goals.
Should your business implement SSO?
If your business runs several services that are accessed by a large number of users (employees, vendors, consumers, etc.), then SSO is definitely worth considering. Here are a few benefits of SSO to remember when making the decision.
Improved user experience: There’s no need for users to remember and manage multiple usernames and passwords. This reduces password fatigue and creates a simple and quick login experience.
Increased security: Users are only required to authenticate once, reducing the risk of password-related security breaches.
Improved productivity: By reducing the time and effort required for employees to access the services they need, SSO can help improve overall productivity and efficiency.
Increased compliance: SSO helps organizations meet regulatory requirements for data privacy and security.
Enhanced user management: Administrators can more easily manage user access and can quickly revoke or modify it as needed. This reduces the risk of unauthorized access to sensitive information.
Improved integration: SSO simplifies the integration of different applications, as it provides a common method for authentication and authorization.
Easy SSO implementation with Descope
If you are building a business app, enterprise customers will expect your app to have SSO capabilities. However, learning and debugging protocols like SAML in-house can be extremely time-consuming and complex. Descope helps developers easily add SAML SSO capabilities to their B2B apps using a drag-and-drop workflow editor and a few lines of code.