LDAP vs SSO

LDAP and SSO are both used for user authentication, but they’re not the same.

LDAP is an open protocol for querying and maintaining data in directories while SSO is an authentication method that allows users to use one set of login credentials to log in to multiple apps.

SSO authentication relies on centralized directories that store user identities to verify users. Sometimes, these directories are LDAP-based directories but not always.

In this article, we'll break down what LDAP and SSO are, the pros and cons of each, and help you decide which authentication method is right for you.

LDAP vs SSO: Which is right for you + what are they?

Lightweight Directory Access Protocol (LDAP) is a protocol used for accessing and managing directory services over an IP network. It allows you to authenticate users by validating user credentials against an LDAP-based directory.

Single Sign-On (SSO) uses authentication protocols like SAML and OpenID Connect to let users log in once to a centralized directory provider and access multiple apps.

So which is right for you?

Use LDAP if you support on-premises deployments and want to allow your customers to authenticate users from an on-prem LDAP-based directory.

Use SSO if you’re building a cloud-based app and want your customers to log in users through SSO.

Use both LDAP and SSO together, if you want to allow SSO authentication from a centralized LDAP-based directory.

What is LDAP?

LDAP is a protocol, or a set of rules, that dictates how information can be accessed and managed over a network.

It is specifically designed for working with directory services. These directory services are centralized locations where user and device data are stored.

Its primary purpose is to enable and facilitate the searching and modifying of this directory information in a network, whether for user management, configuring services, or accessing resources.

However, it can also be used in user authentication when integrated with a directory like Active Directory.

Here’s how it works: When a user tries to access a system or application, the client (which could be an application) sends a request to the LDAP server to authenticate the user. The server then looks up the user's entry in the directory to verify their identity and determines what resources or access levels the user is permitted. This process involves authenticating users through their credentials and authorizing them based on the information stored in an LDAP directory.

Although LDAP is not an SSO solution itself, LDAP-based directories can act as a central repository for user credentials and attributes. SSO providers can leverage LDAP directories to authenticate users against this central directory via Kerberos.

Pros of LDAP

LDAP has the following benefits:

• Centralized management of identities: LDAP allows for the centralized management of user information, making it easier for admins to manage user accounts and permissions across the network.
• Scalability: It is highly scalable and capable of handling thousands of entries and modifications without significant performance degradation. Plus, you can set up LDAP clusters for even larger deployments, from a few dozen employees to a few hundred thousand.
• Fast reads: It’s designed to efficiently manage read, search, and lookup operations, making it exceptionally fast for retrieving information from the directory.
• Interoperability: LDAP is vendor-neutral. It’s supported by a wide range of applications, operating systems, and network devices, making it compatible with diverse IT environments.

Cons of LDAP

Below are some of the downsides of LDAP:

• Poor write operations performance: While LDAP is optimized for read operations, it can be less efficient when handling a high volume of write operations, such as updating or adding a large number of entries frequently.
• Complexity in management and setup: Setting up an LDAP server and directory requires skilled IT staff to configure and maintain, especially in larger environments with extensive security and customization needs. For example, modifying the LDAP schema to accommodate custom requirements can be complicated and, if not done carefully, may lead to issues with data integrity.

What is SSO?

Single Sign-On (SSO) is an authentication method that allows a user to access multiple applications from a single place instead of having to sign in separately to each app.

The primary goal of SSO is to streamline the user experience by reducing the need for multiple logins as they access various systems and services.

It's extremely beneficial for both security and convenience, limiting the number of times a user needs to authenticate and the number of authentication factors like passwords or passkeys the user needs to keep track of.

SSO works by establishing a trusted relationship between an authentication server, usually a part of your customer’s identity provider and your app. When a user first logs in, the SSO system authenticates the user against a central IdP.

Upon successful authentication, the IdP issues a token, which contains claims about the user's identity. Depending on the information within the claims, the app grants access to the user without further prompts.

SSO is enabled by various protocols, the most common ones being:

• SAML: An XML-based open standard for exchanging authentication and authorization data between an identity provider (IdP) and a service provider (SP).
  
  When a user attempts to access a service (SP), they are redirected to the IdP to sign in. Upon successful authentication, the IdP sends a SAML assertion (a form of token) back to the SP. This assertion contains the user’s identity and potentially authorization data, which the SP uses to grant access to the user.
  
  SAML is widely used in enterprise applications.

• OpenID Connect: OIDC is an authentication layer on top of OAuth 2.0, an authorization framework. It extends OAuth 2.0 to add authentication capabilities.
  
  Like SAML, when a user logs in via an IdP the IdP returns an ID token to the app, which is a JSON web token (JWT) that contains information about the authenticated session.
  
  OIDC is more lightweight, flexible, and better suited for mobile apps and APIs compared to SAML. It’s also way easier to implement.

Pros of SSO

SSO offers significant benefits for your customers including:

Convenience

After the initial sign-in, users can seamlessly navigate between different systems and applications without being prompted to log in again. This seamless movement improves productivity and user satisfaction, as it removes friction from the user experience.

SSO requires a centralized identity provider (IdP) that provides a single source of truth for user identities across the organizations. This simplifies the task of managing who has access to what, as all user data and permissions are maintained in one place.

Increased security

SSO can enhance security by enabling organizations to enforce strong authentication policies (like multi-factor authentication) centrally.

Additionally, with a centralized directory, SSO simplifies compliance with various regulatory requirements. It provides clear audit trails of access and authentication events, making it easier to demonstrate compliance with security policies and regulations.

Reduced IT costs

For your customers, SSO reduces costs associated with locked accounts. With fewer accounts to reset once users inevitably forget their authentication details, IT teams spend less time on support calls and unlocking accounts.

For you, as the service provider, SSO means you don’t have to worry about securing user identities in your system or building logic to authenticate users — your customer’s identity provider handles that for you. This saves you a huge chunk of engineering time while also reducing your security risk you have to take on.

Cons of SSO

Some of the disadvantages of SSO include:

Increased vulnerability

Having a centralized authentication system means there’s a single point of failure. If an attacker compromises your customer’s directory, they could gain access to your app. SSO also means a single set of credentials protects many applications, so if those credentials are stolen, the impact is greater.

Added implementation complexity

Your customers use different identity providers, each potentially using different SSO protocols (such as SAML, OAuth, OpenID Connect) or variations within those protocols.

As you build SSO authentication into your app, you’ll need to understand and implement the specific requirements of each IdP’s protocol, which can vary significantly in terms of the authentication flow, security requirements, and data formats. This process may not only take your engineering team so much time but can get quite complex.

What are LDAP and SSO used for?

LDAP is used to centralize user identities in a structured directory and manage access to all resources within an enterprise network.

SSO is used to simplify user access across multiple apps and services, allowing users to log in once and gain access to all the apps they have permission to.

LDAP vs SSO: FAQs

How to use SSO with LDAP?

LDAP is not an SSO protocol but a communication protocol for accessing directories. However, an SSO IdP can integrate with LDAP, allowing someone with an on-premises LDAP directory to use that directory and credentials to authenticate users.

What is the difference between LDAP and Active Directory?

LDAP is a protocol that allows for the querying and modification of directory services running over a network. It is platform-independent and can be used with various directory service implementations.

Active Directory (AD), from Microsoft, is one of the directory services that can use LDAP.

Can SSO work without LDAP?

Yes, SSO can work without LDAP. SSO is a high-level authentication scheme that can leverage various user directories (not just LDAP-based directories) and authentication protocols, including OAuth, OpenID Connect, and SAML.

Next steps

When it comes to SSO authentication, there are various protocols to choose from. In most cases, you’ll want to support SAML and OIDC, the two most popular SSO protocols.

One of the easiest and fastest ways to support these protocols is to use WorkOS. It lets you connect to multiple identity providers like Okta, OneLogin, and Microsoft Entra, with just a single API-based integration.

• Get started fast: With SDKs in every popular language, easy-to-follow documentation and Slack-based support, you can implement SSO in minutes rather than weeks.
• Support every protocol: With OAuth 2.0 integrations to popular providers like Google and Microsoft, compatibility with every major IdP, and full support for custom SAML/OIDC connections, WorkOS can support any enterprise customer out of the box.
• Avoid the back-and-forth: WorkOS’s Admin Portal takes the pain out of onboarding your customers’ IT teams and configuring your app to work with their identity provider.
• Pricing that makes sense: Unlike competitors who price by monthly active users, WorkOS charges a flat rate for each company you onboard — whether they bring 10 or 10,000 SSO users to your app.

Explore Unified SSO by WorkOS.