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SAML vs. OpenID vs. OAuth vs. LDAP: Decoding SSO protocols

Take a deep dive into single sign-on (SSO) protocols. Find out why UserLock SSO takes advantage of SAML vs. OpenID/OAuth/LDAP in Active Directory environments.

Published Sep 27, 2023
SAML vs OpenID vs OAuth vs LDAP

Each time you enjoy the streamlined experience of logging into various apps using just one set of credentials, you’re likely crossing paths with SAML. This key technology powers single sign-on (SSO). This process of single sign-on is where the SAML vs. OpenID vs. OAutH vs. LDAP SSO debate comes into play.

Think of it as your time-saver, eliminating the hassle of separate logins for each application. But how does SAML measure up against other big names in the authentication arena, like OpenID, OAuth, and LDAP?

In today’s digital landscape, where security converges with ease of access and considerations of SSO and Active Directory, understanding the nuances between these protocols is not just a technical hobby — it’s a necessity for everyone. Let’s unpack the distinctions between SAML and its counterparts, demystify the lingo and dig into the mechanisms.

Understanding SAML in the SSO and Active Directory landscape

SAML, standing for Security Assertion Markup Language, is an open standard that eases the authentication experience. Utilizing the Extensible Markup Language (XML) framework creates standards for communication between an entity that authenticates a user’s identity and the specific service or application. SAML vs. OpenID vs. OAutH vs. LDAP SSO is critical in this context.

In essence, SAML facilitates seamless integration of identity authentication and authorization for specific web services.

Take for example our imaginary company TechWorld Inc., a global tech company, facing the challenge of managing user logons across multiple web applications. They integrate SAML with their existing Active Directory to streamline access and enhance security, enabling single sign-on (SSO) capabilities.

Now, their IT help desk receives dramatically less password reset requests, and employees are happy to quickly and easily access the tools they need to get their work done. SSO also allows for centralized user management, an added bonus to the secure, seamless access for employees. As a result, SAML proves essential for efficient user authentication in the modern SSO landscape at TechWorld.

SSO protocols and identity management: SAML vs. all rivals

Over time, SSO protocols have evolved to include multiple standards, each serving a different purpose in the complex choreography of authentication and authorization. OAuth, OpenID Connect, and LDAP form the core of the SAML vs. OpenID vs. OAutH vs. LDAP SSO discussion, and can all be contrasted with SAML (Security Assertion Markup Language).

A framework for authorization vs. federated authentication

The main difference between OAuth 2.0, OpenID Connect, and SAML is their area of specialization. As a framework for authorization, OAuth 2.0 enables secure delegated access to protected resources. OpenID Connect and SAML, on the other hand, specialize in federated authentication, allowing users to verify their identity across multiple services. However, their mechanisms and typical use cases differ.

OAuth2 vs. OpenID Connect

As an extension of OAuth 2.0, OpenID Connect uses JSON Web Tokens (JWT) to provide additional standardization where OAuth 2.0 allows flexibility. In consumer websites and mobile apps, OpenID Connect allows users to log into an Identity Provider (IdP) like Google and access other connected services without signing in separately.


The SAML protocol uses an XML-based messaging format. With a corporate IdP, users can access multiple services, such as Salesforce or Workday, without re-authenticating. In addition to verifying a user’s identity, it relays their permissions.

So, what does all this mean in terms of SSO for Active Directory identities? Basically, SAML allows on-premises AD users to access multiple web applications, like Microsoft 365, using only their AD credentials.

LDAP (Lightweight Directory Access Protocol) stores user credentials and group data within a company. Unlike SAML, OAuth, or OpenID Connect, applications can access LDAP for user data and permissions.

Best Use Cases for SAML vs. OpenID vs. OAuth vs. LDAP

Authentication and authorization protocols ensure secure and efficient service access. Choosing the standard best adapted to your use case, whether SAML, OpenID, OAuth, or LDAP, can be a challenge.

To help organizations make an informed decision, we outline the typical use cases for each.

SAML (Security Assertion Markup Language)

An open standard based on XML that simplifies authentication across domains. With single sign-on (SSO), enterprises can provide seamless access to multiple applications using one set of credentials for their employees.

When to use it: SAML is ideal for organizations that require web-based SSO across multiple applications. For companies that have partnerships with third-party vendors, it facilitates secure access without constant reauthentication.


A decentralized authentication protocol, OpenID facilitates user authentication through third-party identity providers. It enables users to unify their digital identities.

When to use it: OpenID is best for consumer-facing applications. This is an excellent choice for organizations offering users familiar credentials, such as those from Google or Facebook.


OAuth serves as an authorization framework instead of traditional authentication. Access to specific user data is delegated without exposing passwords, focusing on delegated resource access.

When to use it: Opt for OAuth when developing third-party apps that require access to user data on another platform but you don’t want to handle or store user passwords. For instance, a third-party app needing to post tweets on a user’s behalf on Twitter would use OAuth.

LDAP (Lightweight Directory Access Protocol)

As a directory service protocol, LDAP specializes in searching and managing user directories. Combining LDAP and SSO isn't inherent to LDAP, but it is crucial for information lookup and organization.

When to use it: LDAP is the go-to for organizations that want to maintain a centralized directory of users, especially in on-premises environments. It is widely used in corporate settings to manage and look up information about users, like contact details or membership groups.

Consider your organization's specific needs

It’s essential to consider your organization’s specific needs and objectives before choosing SAML, OpenID, OAuth, or LDAP, especially when considering SSO and Active Directory. By recognizing each protocol’s strengths and ideal use cases, you can best create the most secure and efficient experience for both end users and your IT team.

Take for example, another imaginary company GlobalTech Enterprises, seeking to optimize its digital interactions, evaluated four authentication and authorization standards. They adopted SAML for web-based SSO across corporate applications, ensuring seamless access without constant reauthentication.

For consumer-facing applications, they used OpenID, allowing user logins with familiar credentials like Google. Meanwhile, OAuth was chosen for third-party apps requiring user data access without handling passwords, and LDAP was used internally for centralized user directory management.

How SAML and SSO strengthen Active Directory

When combined with SAML SSO, Active Directory (AD) can remain your central hub for user management, even for access to web applications. But how exactly does this SAML-Active Directory integration work? Let’s delve into the mechanics:

  • User login: A user attempts to access a web application (known as a Service Provider or SP). If not already authenticated, the SP directs the user to the Identity Provider (IdP) – in this case, a system using Active Directory.

  • Authentication request: The IdP checks if the user has an active session. If not, it prompts the user for their AD credentials.

  • Authentication with AD: The IdP verifies the provided credentials against the Active Directory database. If the certificates are valid, the IdP constructs a SAML assertion, a package of user information.

  • SAML assertion creation: This SAML assertion, encoded in XML format, contains details about the user’s identity, session data, and other necessary attributes. It vouches for the authenticity of the user.

  • Assertion transmission: The IdP sends this SAML assertion back to the Service Provider.

  • SP verification: The SP evaluates the SAML assertion. If it’s valid (and the assertion confirms the user’s permission to access the service), the SP grants access to the user.

  • Access granted: The user can now seamlessly interact with the web application without undergoing further login prompts, courtesy of the SSO mechanism.

Enhanced security is one of the major benefits of SAML and AD integration. A significant amount of credential exposure is prevented since user credentials aren’t directly passed to the SP.

Additionally, Active Directory’s centralization ensures that user access can be managed uniformly, simplifying administrative tasks and strengthening security.

For example, another imaginary company, MegaCorp. Integrating SAML with their existing Active Directory (AD) revolutionized their web app logon experience. When users accessed a web application, the system used AD as the Identity Provider (IdP) to validate credentials and construct a SAML assertion.

This XML-encoded assertion, containing user details, was sent to the Service Provider, eliminating the need for direct credential exposure and subsequent logins — the integration streamlined user access across web applications, boosting both security and productivity.

Simplify authentication with UserLock SSO

As hybrid IT ecosystems mature, getting a handle on protocols like SAML, OpenID, OAuth, and LDAP is more crucial than ever. In the process, integrating SSO with Active Directory becomes paramount.

For Active Directory environments, SAML stands out as a robust choice. It simplifies authentication while maintaining security layers.

What about UserLock SSO? With UserLock, you can maximize SAML’s potential to provide fluid access without compromising security. Not only does UserLock allow authentication stay on-premise, but it also lets you combine MFA with SSO. The result? You get all the benefits of strong authentication to your line-of-business apps, without the hassle.

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