Hello, everyone. Hi, I'm Rinku, a senior software engineer with extensive experience in authentication and identity management. Over these years, I worked with multiple organizations, helping them implement single sign on solutions using OO2, SAML, and other protocols. Today, I'll walk you through designing a seamless FSO system, the challenges we often face, and how to balance security, performance, and user experience. Not too long ago, enterprise authentication was simple. Each app had its own logging, but as the business has scaled, users were drowning in passwords and IT teams struggled with security gaps, complaints, risk, and access control issues. the SSO solves these challenges, but, implementing it correctly is very critical as a bad SSO system can become a security nightmare. Two dominant protocols for our SSO today are, The first one is OAuth2, which is a token based framework widely used in cloud and microservices architectures. And other one is the SAML, an older XML based standard, which is used in enterprises with legacy applications. Oh, is primarily used for a authorization and is common in mobile apps and web applications. you have probably used it when logging into website like Google, Facebook, Orth instead of creating a new account. And here is how it works. The user tries to log in to an app, known as the client app. The app then redirects the user to an authorization server, such as Google or Facebook, to authenticate. The user enters their credentials, and if successful, the authorization server grants the authorization code. And the app then exchanges this code for an access token. This access token is used to request protected resources from resource servers, such as APIs. And if the token is valid, the resource server grants the access. So in OAuth 2. 0, the user never shares their password with the application. Instead, the access is granted through a secure token. This makes OAuth ideal for scenarios like logging in with Google or accessing third party APIs securely. Now let's talk about SAML, which stands for Security Assertion Markup Language. Unlike OAuth, which is focused on API access, SAML is mainly used for single sign on in enterprise environments. For example, imagine you work for a company and need to log into multiple applications like AWS, Microsoft, or Salesforce. AWS, Instead of entering your credentials repeatedly, SAML allows you to log in once and access all these services. And here is how it works. The user tries to access the application known as a service provider. Instead of asking for a password, the service provider redirects the user to an identity provider such as Okta or Azure. The user enters their credentials on the identity provider login page. If it's successful, the IDP generates the SAML assertion, which is an XML based authentication token, and this SAML assertion is sent back to the service provider, which verifies it. If everything checks out, the user is logged in without entering their password again. in SAML SSO, the authentication happens at the identity provider, and the service provider trusts the SAML token to grant access. This method is widely used in corporate environments where the employees need secure and seamless access to multiple applications. A seamless SSO solution is not about logging in once. It needs to be secure, fast, and easy to use. So if any of these areas are neglected, the adoption rates drop and the security risk increases. The security is the backbone of any SSO system, so we must protect the identity providers and enforce multi factor authentication where necessary, and ensure the tokens are properly encrypted and expired. After a reasonable duration, the token leaks or, repay attacks can compromise the entire system if not managed properly, the performance is often overlooked in security discussion, but it is just as critical. A slow authentication process frustrate the users and increases abandonment rates by, caching tokens and optimizing authentication for so we can reduce the logging delays and keep the experience smooth. The user experience is what makes or breaks SSO adoption. So if users encounter frequent login prompts, inconsistent UI, or compatibility issues, they will either bypass SSO or complain to IT. A great SSO experience should feel invisible. The user must be able to log in once and gain access to all necessary systems without any interruptions. While SSO enhances security by reducing password fatigue and improving access management, it also introduces new security challenges. Let's explore the key risk organizations must address when implementing SSO. If the identity provider is compromised, every connected application is at risk. Since SSO centralizes authentication, An attacker who control, who gains control of the IDP essentially gets unrestricted access to all linked devices. This is why securing the IDP with strong access controls, MFA and continuous monitoring is critical. SSO relies on tokens instead of passwords. While this improves the security, it also makes tokens a high value target for the attackers. If an access token is stolen, it can be used to gain access to sensitive resources. Even worse, replay attacks allows attackers to reuse the valid tokens to hijack user sessions. Another major risk is man in the middle attacks, where an attacker intercepts token exchanges during authentication. If connections between the user, identity provider, and service provider are not properly secured, an adversary can steal or modify the authentication data. Now let's talk about best practices for securing your SSO system. While SSO improves convenience, it also becomes a prime target for attackers. To counter these threats, organizations must follow strict security best practices. First, we always use short lived access tokens. Tokens that last too long increases the risk of being stolen and misused. Instead We should use, we should, issue tokens with a short expiration time and use refresh tokens to extend access when needed. This way, even if an attacker gains access to a token, it becomes useless after a short period. Next is a multi factor authentication, which is a user's credentials are stolen, MFA ensures that a second verification step, such as a push notification, a one time password, or a biometric check is required before access is granted. This dramatically reduces the risk of unauthorized access, even if a password is compromised. Another security measure is token scoping. Not all tokens should have full access to all resources. Instead, we should limit the permissions of each token based on what the user or application actually needs. For example, a token issued to read user data should not be able to modify the system settings. This principle, known as the principle of least privilege, minimizes the damage in case of a breach. Finally, the security doesn't stop at authentication. Organizations must log and monitor authentication attempts for unusual behavior. If we notice repeated, failed login attempts, access from unusual locations, or, tokens being used, abnormally, we can take proactive measures such as blocking suspicious sessions or requiring additional verification. By implementing these best practices, we can significantly strengthen the security of SSO systems while maintaining a smooth user experience. A poorly optimized SSO system can cause slow login times and unnecessary delays in applications. Users expect a seamless experience and any lag in the authentication can lead to frustration and decreased adoption. So let's discuss the three key strategies to optimize performance in an SSO system. First, we can improve the speed by caching authentication tokens. So instead of focusing, focusing users to re authenticate every time they access a system, we store valid tokens temporarily. so this reduces the load on backend identity providers and allows for faster authentication. Next, to handle high traffic and prevent failures, we use load balancing for identity providers. This ensures that authentication requests are distributed effectively, preventing bottlenecks and improving system reliability. If one of the server experiences high demand, another can take over seamlessly. Finally, asynchronous token validation is a powerful way to enhance performance. Instead of making every authentication request block the application, we validate tokens asynchronously. This significantly speeds up API responses, ensuring that users can access their applications without any delay. By implementing these optimizations, we can create a faster, more scalable, and user friendly SSO experience. A seamless SSO experience also means reducing unnecessary logging prompts. The user should authenticate once per session without repeated logins. The branded login pages can enhance the trust and consistency by matching your application's design. Making the users feel they are in the right place. Finally, the session persistence ensures users stay logged in across services, avoiding disruptions and improving workflow efficiency. By focusing on these UX elements, we create a frictionless authentication experience that boosts the user's satisfaction and adoption. Many enterprises still rely on legacy applications that don't support modern authentication standards like OAuth 2. 0 or SAML. So to bridge this gap, we use SSO gateways, which act as a translator, converting the OAuth 2. 0 or SAML request into authentication methods that the legacy system understands. A complete migration can be disruptive. So instead of a big bang approach, we should gradually phase in SSO while maintaining existing authentication. Finally, before a full rollout, it's crucial to test backward compatibility to prevent system failures and ensure a smooth transition. SSO is constantly evolving and the future of authentication is shifting towards stronger security and user control. And one of the major trends is the zero trust model, where no user or device is implicitly trusted and the authentication is continuous rather than a one time check. Next, AI driven security is enhancing authentication by detecting anomalies in real time, identifying suspicious logging patterns, and preventing fraud before it happens. Finally, decentralized identity using blockchain technology is emerging. This allows the users to control their own credentials without relying on central authority, improving privacy, and reducing identity theft risk. These advancements will shape the next generation of SSO, making it more secure, intelligent, and user centric. Here are the key takeaways. SSO is more than just reducing logs. It's about enhancing security, scalability, and user experience first, choosing the right authentication, protocol exclusion, all 2.0 for. Finally, balance the security performance and usability by securing every authentication flow. A well designed SSO system strengthens security while providing a seamless user experience. Thank you so much for listening. And if you found this valuable, let's connect on LinkedIn or follow me for more insights. And I would love to hear your thoughts.