Sunday, 14 Jul 2024

What Is Single Sign-On Authentication (SSO) And How Does It Work?

Single Sign-On (SSO) authentication is a crucial aspect of federated identity systems, providing a centralized login system for accessing various websites and services. In this post, we will explore the concept of SSO authentication, its implementation for the web, and how it works.

Federated Identity Glossary

Federated identity refers to the concept of a centralized or linked electronic identity. It involves handling various concerns such as authentication, authorization, user attributes exchange, and user management.

  • Authentication validates user credentials and establishes their identity.
  • Authorization determines access restrictions for users.
  • Attributes exchange involves sharing data across different user management systems to prevent data duplication.
  • User management involves the administration of user accounts.

SSO focuses exclusively on the authentication aspect of a federated identity system, establishing the user’s identity and sharing that information with each subsystem that requires it.

Single Sign-On (SSO) Authentication

SSO authentication solves the problem of sharing login information across different domains and allowing users who are already logged in on one domain to be automatically logged in on another domain. However, the same-origin policy enforced by browsers restricts cross-domain access to cookies and other locally stored data.

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SSO protocols address this restriction by sharing session information in different ways. A central domain handles the authentication process and shares the session with other domains. For example, a central domain can generate a signed JSON Web Token (JWT) encrypted using JSON Web Encryption (JWE). This token contains all the necessary information to identify the user for domains requiring authentication and cannot be modified by the client.

Whenever users visit a domain that requires authentication, they are redirected to the authentication domain. Since they are already logged in there, they can be immediately redirected back to the original domain with the appropriate authentication token.

SSO Authentication with Auth0

There are various implementations of SSO, such as OpenID Connect, Facebook Connect, SAML, and Microsoft Account. It is recommended to choose the simplest implementation for your development efforts. Interoperability between different SSO solutions can be achieved using frameworks like Auth0.

Auth0 acts as the authentication server and bridges different SSO frameworks, simplifying the integration of SSO into new or existing applications. It provides comprehensive documentation on SSO and offers SSO samples to facilitate integration.

Frequently Asked Questions

  • Q1: Can SSO be used in enterprise developments?

    • Yes, SSO, particularly SAML, is widely used in enterprise developments.
  • Q2: Is it possible to integrate multiple SSO solutions?

    • Yes, there are frameworks available that allow interoperability between different SSO solutions.
  • Q3: Does Auth0 support SSO implementation?

    • Yes, Auth0 acts as an authentication server and supports the integration of various SSO frameworks.
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SSO authentication is an essential aspect of decentralized systems, providing a solution for managing a growing number of users across multiple applications and services. Frameworks like OpenID Connect and services like Auth0 simplify the integration of SSO into new or existing applications. Consider incorporating SSO from the beginning when implementing authentication for your application or service.

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