What Is SSO (Single-Sign-On)?

SSO (Single-Sign-On) is an advanced user authentication mechanism designed to enhance the user experience and bolster security. At its core, SSO lets users access multiple applications or platforms using just a single set of credentials, typically a username and password. This not only eliminates the need to remember multiple passwords but also streamlines the sign-in process for various services. Over time, the concept of SSO has evolved, branching out into different configurations and applications, making it a cornerstone in the digital authentication landscape.

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SSO operates primarily through a federated identity management system, often referred to as identity federation. One of the renowned frameworks in this domain is OAuth, which serves as an intermediary. Instead of sharing a user's password, OAuth grants third-party services an access token, safeguarding the user's sensitive login information. When a user tries to access a particular application, the service provider collaborates with the identity provider to authenticate the user's credentials. Once authenticated, the user can freely access the application without any further prompts.

Various protocols underpin SSO services. Kerberos, for instance, employs a ticket-granting ticket (TGT) mechanism, ensuring users aren't repeatedly prompted for credentials. On the other hand, Security Assertion Markup Language (SAML) is a distinct protocol that exchanges user authentication and authorization data securely across platforms. Furthermore, smart card-based SSO configurations use cards embedded with sign-in data, further simplifying the login process.

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SAML (Security Assertion Markup Language) is a robust authentication protocol widely embraced in enterprise environments to streamline user access to various applications, like CRM systems, through a single sign-on (SSO) process. Read more about SAML here.

SSO and password managers both aim to simplify the user authentication process. However, SSO offers a unified method for users to access multiple applications with one set of credentials. In contrast, password managers store individual passwords for various services, automatically inputting them upon request.

While SSO enhances user convenience, it does introduce potential security vulnerabilities. If a malevolent actor gains access to a user's SSO credentials, they can infiltrate all associated applications. Therefore, it's paramount to bolster SSO with added layers of security, such as two-factor authentication (2FA) or multifactor authentication.

Platforms like Facebook, Google, and LinkedIn offer Social SSO, allowing users to log into third-party platforms using their social media credentials. While this provides a seamless login experience, it does pose potential security risks, as a breach in one platform could jeopardize others.

Integrating passkeys with SSO provides a modern, secure authentication method. By combining the two, users benefit from the streamlined login of SSO and the enhanced security of passkeys. Platforms like Corbado seamlessly integrate these features, ensuring users enjoy a convenient yet secure digital experience.

IdP-initiated means that the login process begins at the Identity Provider (IdP), sending a SAML assertion to the Service Provider (SP). In contrast, SP-initiated SSO starts when a user attempts to access a service directly at the SP's site, redirecting him to the IdP to log in.