What is Single Sign-On (SSO)?

 

✅ What is Single Sign-On (SSO)?

Single Sign-On (SSO) is an authentication process that allows a user to log in once and gain access to multiple applications or systems without having to log in again for each of them.

👉 Example:

• You log into your Google account, and you automatically get access to Gmail, YouTube, Google Drive, Google Docs, etc., without signing in separately for each service.

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✅ How SSO Works — Step by Step:

Step	Description
1️⃣ User Login Request	The user visits an application (called the Service Provider, e.g., Gmail) and tries to log in.
2️⃣ Redirect to Identity Provider (IdP)	The application redirects the user to an Identity Provider (IdP) (e.g., Google Identity, Okta, Azure AD) to authenticate.
3️⃣ Authentication	The user enters login credentials only once at the Identity Provider.
4️⃣ Token/Session Creation	If the credentials are correct, the IdP creates a secure token (like SAML, OAuth, or OpenID Connect token).
5️⃣ Redirect Back	The user is redirected back to the application with the token.
6️⃣ Access Granted	The application validates the token, and the user gets access. Now the user can access other related applications without logging in again.

✅ SSO Common Terms:

• Identity Provider (IdP): Authenticates user identity (e.g., Okta, Google).

• Service Provider (SP): The application the user wants to access (e.g., Gmail, Salesforce).

• Token: A digitally signed document verifying user identity (SAML, OAuth, JWT).

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✅ Benefits of SSO:

• ✔️ One Login for multiple services

• ✔️ Better user experience

• ✔️ Reduced password fatigue

• ✔️ Stronger security controls at one central point

• ✔️ Easier IT management

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✅ Disadvantages of SSO:

• ❗ If SSO is compromised, all connected services are at risk.

• ❗ Initial setup can be complex.

• ❗ Dependency on Identity Provider availability.

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✅ Common SSO Protocols:

• SAML (Security Assertion Markup Language) → Popular in Enterprises

• OAuth 2.0 → Used by apps like Google, Facebook

• OpenID Connect → Built on top of OAuth 2.0 for identity verification

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