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115. What is single sign-on? How to implement it?

Single sign-on (SSO) is an authentication mechanism that allows users to authenticate only once, and access multiple applications or services without the need for separate authentication every time.

There are different ways to implement SSO, but the most common one is to use a third-party identity provider (IDP) that acts as the authentication source for all participating applications. The IDP generates a unique token for the user after authenticating them, which is then passed to the applications as proof of authentication. The applications can then verify the token with the IDP to grant access to the user.

Another way to implement SSO is using session sharing, where the user's session is shared between applications in the same domain. This can be done using cookies or by passing the session ID in the URL.

The pros of implementing SSO are improved user experience, simplified authentication process, and reduced administrative costs. However, there are also potential cons such as increased security risks and dependency on the reliability of the IDP.

To implement SSO, one can use standard protocols such as SAML, OAuth, or OpenID Connect, or use proprietary solutions with SDKs or plugins provided by the IDP vendor. It is important to ensure proper security and privacy controls are in place, and to test the implementation thoroughly before deployment.