Service Provider (SP) Mode

In SAML 2.0 (OASIS XML-based SSO standard), a Service Provider trusts an Identity Provider to authenticate users and issue signed assertions. Configure LumoAuth as a SAML SP to accept logins from external IdPs like Okta, Azure AD, OneLogin, PingIdentity, or ADFS. Use SP mode when users already have identities in a corporate directory and you want them to sign into LumoAuth-protected applications with those credentials.

SP-Initiated SSO Flow

In the SP-initiated flow, the user begins at your application and is redirected to the external IdP for authentication.

SP Metadata Endpoint

GET /orgs/\{orgId\}/saml/sp/metadata

Returns the SAML SP metadata XML document. Provide this URL to your external IdP to configure the integration automatically.

Example Request

curl https://app.lumoauth.dev/orgs/acme-corp/saml/sp/metadata

Response

MIICo...
                
            
        
        
        
        
        
            urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress

SSO Login Endpoint

GET /orgs/\{orgId\}/saml/sp/login

Initiates the SAML SSO flow by generating an AuthnRequest and redirecting the user to the configured external IdP.

Parameters

Parameter	Required	Description
RelayState	No	URL to redirect to after successful SSO

Example

url

https://app.lumoauth.dev/orgs/acme-corp/saml/sp/login
    ?RelayState=https://app.example.com/dashboard

Login with Specific IdP

GET /orgs/\{orgId\}/saml/sp/login/\{idpId\}

When multiple IdPs are configured, use this endpoint to specify which IdP to use:

url

https://app.lumoauth.dev/orgs/acme-corp/saml/sp/login/42

Assertion Consumer Service (ACS)

POST /orgs/\{orgId\}/saml/sp/acs

Receives and processes SAML Responses from the IdP. This endpoint:

• Validates the SAML Response signature
• Verifies the assertion audience and timestamps
• Extracts user attributes from the assertion
• Creates or updates the user (JIT provisioning)
• Establishes a session and redirects to RelayState

Request Body (from IdP)

Parameter	Description
SAMLResponse	Base64-encoded SAML Response XML
RelayState	Optional redirect URL preserved from AuthnRequest

Direct Calls Not Supported

The ACS endpoint only accepts SAML responses from configured IdPs. Do not call it directly — it is only meant to be invoked as part of the SSO redirect flow.

Single Logout (SLO)

GET/POST /orgs/\{orgId\}/saml/sp/slo

Handles Single Logout requests and responses. Supports both IdP-initiated and SP-initiated logout.

Configuration Guide

Step 1: Get Your SP Metadata

Copy your SP metadata URL and provide it to your external IdP:

Your SP Metadata

https://app.lumoauth.dev/orgs/{your-organization}/saml/sp/metadata

Step 2: Configure the External IdP

In your IdP's admin console, create a new SAML application with these settings:

Setting	Value
ACS URL	https://app.lumoauth.dev/orgs/\{organization\}/saml/sp/acs
Entity ID	https://app.lumoauth.dev/orgs/\{organization\}/saml/sp/metadata
NameID Format	emailAddress
SLO URL	https://app.lumoauth.dev/orgs/\{organization\}/saml/sp/slo

Step 3: Add the IdP to LumoAuth

1. Navigate to SAML IdPs in your organization portal
2. Click Add IdP
3. Enter the IdP's metadata:

• Entity ID: IdP's unique identifier
• SSO URL: IdP's Single Sign-On endpoint
• Certificate: IdP's X.509 signing certificate

4. Configure security and provisioning options
5. Save and test

Security Settings

Setting	Default	Description
Require Signed Responses	✓ Enabled	Verify the SAML response is signed by the IdP
Require Signed Assertions	✓ Enabled	Verify the assertion within the response is signed
Sign AuthnRequests	Disabled	Sign authentication requests sent to the IdP
Clock Skew Tolerance	180 seconds	Allowable time difference for assertion validation

Just-In-Time (JIT) Provisioning

JIT provisioning automatically creates user accounts on their first SAML login:

Setting	Description
JIT Provisioning Enabled	Create new users automatically on first login
Update User on Login	Sync user attributes from SAML on each login
Default Roles	Roles assigned to newly provisioned users

Attribute Mapping

SAML attributes are mapped to user fields automatically:

SAML Attribute	User Field
email, mail, emailAddress	Email
displayName, name, cn	Display Name
givenName, firstName	First Name
surname, lastName, sn	Last Name

Popular IdP Configuration

Okta

1. In Okta Admin, go to Applications → Create App Integration → SAML 2.0
2. Set Single sign on URL to your ACS URL
3. Set Audience URI to your SP Entity ID
4. Configure attribute statements (email, firstName, lastName)
5. Copy the IdP metadata URL from the Sign On tab

Azure AD / Entra ID

1. In Azure Portal, go to Enterprise Applications → New application → Non-gallery
2. Set up single sign-on → SAML
3. Enter your SP Entity ID and Reply URL (ACS)
4. Download the Federation Metadata XML

OneLogin

1. In OneLogin, go to Applications → Add App → SAML Custom Connector
2. Configure ACS URL and Audience
3. Download the IdP metadata

Error Responses

Error	Cause	Solution
Invalid Signature	IdP certificate mismatch	Update the IdP certificate in your configuration
Audience Mismatch	SP Entity ID doesn't match	Verify the Audience in IdP matches your SP Entity ID
Assertion Expired	Clock skew between servers	Sync server clocks or increase clock skew tolerance
No IdP Configured	Missing IdP configuration	Add the IdP configuration in the organization portal
Missing NameID	IdP not sending NameID	Configure NameID in the IdP application settings