If you are trying to understand what is SAML authentication, the basic idea is fairly simple. SAML allows an application to rely on a trusted identity provider to verify a user's identity instead of handling that login itself. This is one of the reasons SAML is widely used for enterprise Single Sign-On (SSO).
SAML, or Security Assertion Markup Language, provides a standard way for an Identity Provider (IdP) and a Service Provider (SP) to exchange information about a user's authentication and identity.
What Is SAML Authentication?
SAML authentication is a way for one system to confirm a user's identity to another system without requiring the user to maintain a separate login for every application.
So, what is SAML in practical terms? It is an open standard that uses XML-based messages to exchange authentication, attribute, and authorization information between trusted systems. SAML is commonly used for enterprise SSO, where an organization's Identity Provider authenticates employees and connected applications act as Service Providers.
SAML stands for Security Assertion Markup Language. The name can sound more complicated than the concept itself. The important part is that SAML defines how identity information is packaged and exchanged between systems that already have a trust relationship.
For example, an employee may already be signed in through the organization's identity platform. When they open a connected business application, the application can use SAML to receive information confirming that the user has been authenticated.
The application does not need to ask the employee for another application-specific password.
Why Is SAML Authentication Used?
Managing separate usernames and passwords for every business application quickly becomes difficult. Employees may use email, CRM, HR, collaboration, finance, and other cloud applications throughout the day.
SAML gives organizations a way to centralize authentication through an Identity Provider while allowing users to access connected applications through SSO.
This has practical benefits for both users and IT teams. Users have fewer separate passwords to manage, while administrators can apply authentication policies from the identity system rather than managing credentials independently inside every application.
SAML is particularly useful when an organization needs to provide SSO across different security domains or connect enterprise applications to a central identity provider.
How Does SAML Authentication Work?
The SAML authentication flow usually involves the user's browser, the Service Provider, and the Identity Provider.
A common SP-initiated flow starts when the user tries to access an application. The application sends a SAML request to the IdP. After authenticating the user, the IdP returns a SAML response containing an assertion. The Service Provider validates that response and creates a session for the user.
Step 1 – User Requests Access to an Application
The user opens an application that requires authentication. If the application does not have an active session for that user, it starts the SAML login process.
Step 2 – Identity Provider Authenticates the User
The user is directed to the Identity Provider. If they are not already authenticated, the IdP asks them to sign in.
The IdP may also apply additional security controls, such as MFA, before completing authentication.
Step 3 – Identity Provider Generates a SAML Assertion
After successful authentication, the IdP creates a SAML assertion. This is an XML-based statement containing information about the authenticated user and the authentication event. Depending on the configuration, it can also contain user attributes and authorization-related information.
Step 4 – Service Provider Validates the Assertion
The SAML response is sent back to the Service Provider, usually through the user's browser.
The SP validates the response and assertion before accepting it. This includes checking the digital signature and other conditions defined by the SAML configuration.
Step 5 – User Gains Access
If the response passes validation, the application creates a session for the user and provides access to the requested resource.
From the user's perspective, the process may simply look like being signed in automatically.
Core Components of SAML Authentication
There are a few terms you need to understand to make sense of a SAML setup.
Identity Provider (IdP)
The Identity Provider is responsible for authenticating the user and providing identity information to applications.
Examples include enterprise identity platforms such as Microsoft Entra ID, Okta, and Ping Identity.
Service Provider (SP)
The Service Provider is the application or service the user wants to access. It relies on the IdP to verify the user's identity.
A SaaS application, internal business application, or enterprise web application can act as an SP.
SAML Assertion
A SAML assertion is the statement issued by the IdP about the user. It can contain authentication information, user attributes, and authorization decision information.
The SP uses this information to decide whether it should establish a session for the user.
Metadata and Digital Certificates
SAML metadata allows the IdP and SP to share configuration information, including identifiers, endpoints, supported services, and key information used for signing or encryption.
Digital certificates are also used to establish trust and verify signed SAML messages.
What Is a SAML Assertion?
A SAML assertion is an XML-based statement made by an Identity Provider about a subject, usually the user.
SAML defines different types of statements that can appear in assertions:
- Authentication Assertion: Provides information about how and when the user was authenticated.
- Attribute Assertion: Provides information about the user, such as an email address, department, or role.
- Authorization Decision Assertion: Communicates an authorization decision related to access to a resource.
These statements allow the Service Provider to receive information from the IdP without having to authenticate the user independently.
What Is SAML 2.0?
SAML 2.0 is the version of SAML most commonly associated with modern enterprise SSO. It was approved as an OASIS Standard in 2005 and defines the syntax and semantics for XML-encoded assertions covering authentication, attributes, and authorization.
When people search for SAML 2.0 authentication, they are generally referring to authentication and SSO flows built using the SAML 2.0 standard.
SAML 2.0 also provides standardized profiles and mechanisms for federation and browser-based SSO, which helped make it practical for applications and identity providers from different vendors to work together.
Benefits of SAML Authentication
SAML is still widely used in enterprise environments because it addresses several common identity and access requirements.
- Single Sign-On: Users can access connected applications without maintaining a separate login for each one.
- Centralized identity: Authentication can be handled through a central Identity Provider.
- Better user experience: Users spend less time entering credentials across applications.
- Reduced password fatigue: Fewer application-specific passwords are required.
- Enterprise integration: SAML allows applications from different vendors to participate in a federated authentication setup.
- Security controls: Authentication policies, including MFA where supported by the IdP, can be applied before access is granted.
- Simpler access management: Administrators can manage application access through the identity platform.
SAML's role is particularly useful in enterprise environments where many applications need to rely on the same identity system. Microsoft Entra, for example, supports SAML-based SSO for enterprise applications.
SAML vs Other Authentication Technologies
SAML is often discussed alongside OAuth, OpenID Connect, and LDAP, but these technologies do different jobs.
SAML vs OAuth: SAML is commonly used for browser-based enterprise authentication and SSO. OAuth is an authorization framework designed to let an application obtain limited access to resources without receiving the user's password.
SAML vs LDAP: LDAP is commonly used to access and manage directory information. SAML is designed for exchanging authentication and identity information between trusted systems.
It is also worth separating authentication from authorization. Authentication answers "Who is this user?" while authorization determines what that user is allowed to access.
For modern applications, OpenID Connect (OIDC) is another important option. OIDC builds an authentication layer on OAuth 2.0 and is commonly used for modern web and mobile applications. SAML remains widely used where enterprise application compatibility and federation are important.
Conclusion
SAML authentication provides a standard way for an Identity Provider to communicate a user's authenticated identity to a Service Provider. Its main role is to support trusted authentication and SSO between separate systems.
Understanding the relationship between the IdP, SP, SAML request, SAML response, and SAML assertion makes the technology much easier to understand. For organizations connecting multiple enterprise applications to a central identity platform, SAML 2.0 remains an established option for federated authentication and SSO.
FAQs for what is SAML Authentication
What is SAML?
SAML stands for Security Assertion Markup Language. It is an open standard used to exchange authentication and identity information between trusted systems.
What does SAML stand for?
SAML stands for Security Assertion Markup Language.
How does SAML work?
The application sends an authentication request to the IdP, the IdP authenticates the user and returns a SAML response, and the application validates the response before granting access.
What is a SAML assertion?
A SAML assertion is an XML-based statement from the Identity Provider containing information about an authenticated user.
What is SAML 2.0?
SAML 2.0 is the widely used version of the SAML standard for exchanging authentication, attribute, and authorization information.
What is SAML SSO?
SAML SSO uses the SAML standard to let users authenticate through an Identity Provider and access connected applications without signing in separately to each one.
What is a SAML Identity Provider?
A SAML Identity Provider authenticates users and sends identity information to Service Providers through SAML messages.