What is Single Sign-On (SSO)? All You Need to Know

You use many different applications every day. Each one asks you for a username and password. Keeping track of all these login details becomes a major headache. Single Sign-On (SSO) solves this big problem.

Single Sign-On (SSO) can be understood as an authentication process. This process allows a user to enter a single set of login credentials—like a username and password—to access multiple independent applications. Imagine one master key that unlocks every door you need to pass through. You enter the details once, and you are good to go for the rest of your session.

What is Single Sign-On (SSO)? 

Single Sign-On (SSO) is a session or user authentication service. This service permits you to use a single ID and password to access several applications. SSO helps you manage many user accounts and passwords. It reduces the time you spend logging in again and again.

What does Single Sign-On mean for your daily work? It means a smoother, faster, and less frustrating user experience. It also means you use stronger passwords because you only need to remember one.

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Comparison: Traditional Login vs. Single Sign-On

To understand the value of this technology, let us start by comparing it with the traditional login method.

What is Single Sign-On Authentication

Single Sign-On authentication refers to how the system verifies you as a valid user. It uses a trust relationship between two main entities:

1. Identity Provider (IdP): This system verifies your identity. It is the one that asks you for your username and password. Examples include services like Okta or Active Directory.
2. Service Provider (SP): This is the application or website you want to access, like a CRM or project management tool. It relies on the IdP to confirm your identity.

The IdP manages the authentication process. It checks your credentials against its user database. When you successfully log in, the IdP generates a security token. This token acts as your digital passport. The Service Provider accepts this token as proof that you are the person you claim to be.

SSO authentication relies heavily on security protocols. Why is Single Sign-On secure? It is secure because it does not share your password with every application. Only the Identity Provider ever sees your password.

Also Read: What is Biometric Authentication? Methods & Security Guide

How Single Sign-On Works?

To understand how Single Sign-On works, we must look at the step-by-step process. This process involves the user, the application (Service Provider or SP), and the central system (Identity Provider or IdP).

Let us explore the sequence of steps:

1. Initial Access

• The user tries to access a protected application, the Service Provider.
• The Service Provider immediately notices that the user has no active session or security token.

2. Redirection to the Identity Provider (IdP)

• The Service Provider directs the user's web browser to the Identity Provider's login service.
• This redirection includes a request for authentication. The SP essentially asks the IdP, "Please verify this user for me."

3. Authentication by the IdP

• The Identity Provider asks the user to enter their SSO login credentials.
• The user inputs their username and the single, master password.
• The IdP verifies these credentials against its centralized user directory. This process confirms your identity.

4. Token Generation

• Once the IdP confirms the user's identity, it creates a security token. This token is a small piece of digitally signed data. It contains information about the user, such as their username and access rights.
• This process often uses a standard security protocol.

5. Return to the Service Provider

• The Identity Provider sends the user's browser back to the Service Provider. The security token is included in this communication.
• The Service Provider receives this token.

6. Token Validation and Access Grant

• The Service Provider checks the digital signature on the token. It verifies that the token truly came from the trusted Identity Provider.
• If the validation succeeds, the Service Provider confirms the user's identity.
• The application grants the user access without asking for the username and password again. A secure session is established.

This systematic flow ensures that your sensitive credentials stay safe with the Identity Provider. The application, or Service Provider, only sees the proof of authentication—the token.

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Key Protocols that Facilitate SSO

Single Sign-On relies on several industry-standard protocols. These protocols define the structure of the communication and the security token. Knowing these helps you understand how does Single Sign-On work at a technical level.

1. Security Assertion Markup Language (SAML)

• SAML is the most common protocol for enterprise SSO.
• SAML can be understood as an XML-based framework. This framework exchanges authentication and authorization data between the IdP and the SP.
• The SAML assertion—the security token—proves that the IdP successfully authenticated the user.
• Due to the use of digital signatures, the Service Provider can ensure that the assertion has not been tampered with.

2. OpenID Connect (OIDC) and OAuth 2.0

• OAuth 2.0 is an authorization framework. It allows an application to gain limited access to a user's account on an HTTP service.
• OpenID Connect (OIDC) is an authentication layer. It sits on top of the OAuth 2.0 framework.
• OIDC can be used to verify the user's identity. It obtains basic profile information about the user.
• Many social media logins use this modern standard.

3. Kerberos

• Kerberos is a network authentication protocol. It uses secret-key cryptography.
• Kerberos is the SSO standard for many internal corporate networks.
• The user's password never travels across the network. Kerberos works on the principle of a trusted third party, called the Key Distribution Center (KDC).

Single Sign-On Integration: Types and Implementations

What is Single Sign-On integration? It refers to the technical steps involved in setting up the relationship between the IdP and the SP. How to implement Single Sign-On depends heavily on the type of applications you use.

1. Federation-Based SSO

• This is the most secure and modern approach. It uses protocols like SAML and OIDC.
• Integration is based on mutual trust and the exchange of cryptographically signed tokens.
• It works well for cloud applications and services outside the corporate network.

2. Agent-Based SSO

• This technique involves installing a small SSO agent or plug-in on the web server of the Service Provider.
• The agent intercepts the user's access request. It then communicates with the central SSO server to check for a valid session.
• This method is often used for in-house, legacy applications.

3. Password Vaulting (Less Common/Legacy)

• This approach stores all the user's application passwords in an encrypted vault.
• The SSO system automatically enters the username and password for the user when needed.
• While it achieves a form of single sign-on, it exposes the actual passwords to the system. This makes it less secure than token-based approaches.

Also Read: What is Click Fraud? Detection, Prevention & Tools

Benefits of Implementing SSO

Implementing SSO provides significant benefits to both the user and the organization.

1. Improved User Experience

• Users only need to remember one password. This reduces password fatigue.
• Access to different applications is instant and seamless.

2. Enhanced Security

• SSO encourages users to use a stronger, more complex single password. This is because they only have one to remember.
• It reduces the risk of phishing attacks. Users are less likely to enter their credentials on fake login pages when they know only the central IdP asks for them.
• Centralized logging allows the organization to track all access attempts in one place. This makes security audits and breach detection much easier.

3. Reduced IT Costs

• Password reset requests are the top reason for help desk calls. Single Sign-On significantly cuts down on these calls.
• The cost savings in IT support make the initial investment in SSO hardware or software worthwhile.

4. Simplified Compliance

• SSO helps companies meet regulatory requirements for user access control and data protection.
• The system automatically enforces password policies—such as complexity and expiration—across all integrated applications.

Managing SSO: Enabling and Disabling

The questions "Is Single Sign-On enabled?" and "How to enable Single Sign-On?" are common. The answers depend on your organization's setup.

How to Enable Single Sign-On

Enabling Single Sign-On involves a systematic process:

1. Select an Identity Provider (IdP): You choose a suitable IdP system, like Microsoft Azure AD, Okta, or Ping Identity. The IdP serves as the central authority.
2. Configure the IdP: You set up your corporate user directory within the IdP. This includes defining the user accounts and security policies.
3. Integrate Applications: For each application (Service Provider) you want to protect, you configure the connection. This means exchanging metadata and certificates with the IdP. This step defines the Single Sign-On integration.
4. Test and Deploy: You test the SSO connection for a small group of users. Once successful, you deploy it company-wide.

How to Disable Single Sign-On

In certain situations, you may need to disconnect a user or an application. How to disable Single Sign-On for a user is simple:

• You immediately deactivate or delete the user's account within the central Identity Provider.
• Because the Service Provider relies on the IdP for validation, the user loses access to all linked applications instantly. This makes SSO a powerful tool for rapid user off-boarding.

Disabling SSO for a specific application involves removing the trust configuration between that Service Provider and the IdP. The application then reverts to its original login method.

Conclusion

So, with the above discussion, we can say that Single Sign-On (SSO) is an essential technology for modern organizations. SSO is nothing but the master key to a streamlined and safer digital experience. It addresses the twin problems of user frustration and weak security. It simplifies your life by requiring you to remember only one strong set of credentials. For the company, it plays a vital role in reducing IT support costs and improving overall security posture.

You now understand what is Single Sign-On. You also see how Single Sign-On works using protocols like SAML and the core relationship between the Identity Provider and the Service Provider.

Our focus remains on delivering solutions that ensure your organizational identity is protected. We offer expert guidance to help you successfully plan and execute your Single Sign-On integration. 

Talk to our security specialists today to start building a future where your team works faster and safer.

Key Takeaways

• SSO requires only one set of credentials (username/password) to access multiple independent applications. This greatly improves user convenience.
• The Identity Provider (IdP) authenticates the user, then issues a secure, non-password token to the application (Service Provider).
• SSO enhances security because users create and use a single, strong password. It reduces common password-related cyber risks.
• Protocols like SAML and OIDC form the technical foundation for SSO, enabling secure communication between the IdP and applications.
• Implementing SSO reduces calls to the IT help desk for password resets, leading to significant cost savings and higher productivity.

Frequently Asked Questions (FAQs)

1. Is Single Sign-On Secure?

Single Sign-On is secure when implemented correctly. It prevents users from creating weak passwords for many different services. The SSO system enforces strong security measures. For example, it often requires multi-factor authentication (MFA) at the point of the single login. This adds an extra layer of protection to your master credential.

2. What is the difference between SSO and Multi-Factor Authentication (MFA)?

SSO is about convenience and reducing the number of times you log in. MFA is about increasing security by requiring multiple proofs of identity. You can, and should, use them together. When you use SSO, you typically use MFA only once, at the start of your day, to prove your identity to the IdP.

3. Does SSO store my password for every application?

No. This is a common misunderstanding. The Identity Provider (IdP) stores your master password. Individual applications (Service Providers) never see your password. They only receive a temporary security token from the IdP. This token confirms your identity without revealing your secret password.

4. What are the common challenges with SSO?

The main challenge is the "single point of failure". If the central Identity Provider goes down, you lose access to all linked applications. Therefore, it is essential to ensure the IdP system is highly available and redundant. Also, the initial Single Sign-On integration can be complex, especially with older, non-standard applications.