Single Sign-On (SSO)

Single Sign-On (SSO) is an authentication and access control mechanism that allows a user to log in once and gain access to multiple applications or services without the need to provide separate sets of credentials (e.g., username and password) for each individual system.

In an SSO system, a user authenticates themselves once, and then a Trusted Identity Provider (IdP)|trusted identity provider (IdP) issues an authentication token. This token is used to verify the user's identity and grant access to various integrated applications or services without the need for additional login prompts.

The identity provider is responsible for authenticating users and issuing authentication tokens. It serves as the trusted source of user identities. Common IdPs include Active Directory, OAuth providers like Google or Facebook, and dedicated identity management systems.

The service provider is an application or system that relies on the IdP for user authentication. It trusts the IdP to provide accurate user identity information. Examples of SPs include web applications, cloud services, and internal company systems.

After a user successfully logs in to an IdP, the IdP issues an authentication token or assertion. This token is a proof of authentication and contains information about the user. The token is then presented to SPs to gain access without re-entering credentials.

The SSO flow is the process by which a user logs in once to the IdP and subsequently gains access to multiple SPs. The flow typically involves a series of redirects and token exchanges between the user, IdP, and SPs.

SSO systems often include session management mechanisms to keep track of authenticated sessions. This ensures that users remain authenticated as they navigate between different SPs during a session. SSO implementations commonly include security measures like Multi-Factor Authentication (MFA)|multi-factor authentication (MFA) to enhance user identity verification. MFA requires users to provide additional authentication factors beyond a password.

SSO simplifies the user experience by reducing the number of times users need to enter credentials. Users can access multiple services seamlessly. SSO allows organizations to implement stronger authentication methods like MFA, enhancing security. It also reduces the risk of users reusing weak passwords across multiple services.

SSO reduces the administrative overhead of managing user accounts and passwords for multiple systems. It simplifies user provisioning and deprovisioning. SSO systems often provide detailed audit logs and reporting capabilities, making it easier to monitor and track user access to various services.

Users are less likely to abandon or forget their credentials, leading to higher user adoption rates for applications and services.