Custom claims provider reference

Artikkeli
07/26/2024

In this reference article, you can learn about the REST API schema and claims mapping policy structure for custom claim provider events.

Token issuance start event

The custom claims provider token issuance event allows you to enrich or customize application tokens with information from external systems. This information that can't be stored as part of the user profile in Microsoft Entra directory.

Component overview

To set up and, integrate a custom extension with your application requires multiple components to be connected. The following diagram shows a high level view of the configuration points, and relationships that are created to implement a custom extension.

You should have a REST API endpoint publicly available. In this diagram, it represented by Azure Function. The REST API generates and returns custom claims to the custom extension. It's associated with a Microsoft Entra application registration.
You require to configure a custom extension in Microsoft Entra ID, which is configured to connect to your API.
You require an application that receives the customized tokens. For example https://jwt.ms a Microsoft-owned web application that displays the decoded contents of a token.
The application, such as the https://jwt.ms must be registered into Microsoft Entra ID using app registration.
You must create an association between your application and your custom extension.
You can optionally secure the Azure Function with an authentication provider, in this article we use your Microsoft Entra ID.

REST API

Your REST API endpoint is responsible for interfacing with downstream services. For example, databases, other REST APIs, LDAP directories, or any other stores that contain the attributes you'd like to add to the token configuration.

The REST API returns an HTTP response to Microsoft Entra ID containing the attributes. Attributes that return by your REST API aren't automatically added into a token. Instead, an application's claims mapping policy must be configured for any attribute to be included in the token. In Microsoft Entra ID, a claims mapping policy modifies the claims emitted in tokens issued for specific applications.

REST API schema

To develop your own REST API for the token issuance start event, use the following REST API data contract. The schema describes the contract to design the request and response handler.

Your custom extension in Microsoft Entra ID makes an HTTP call to your REST API with a JSON payload. The JSON payload contains user profile data, authentication context attributes, and information about the application the user wants to sign-in. The id value in the following JSON is a Microsoft application that represents the Microsoft Entra authentication events service. The JSON attributes can be used to perform extra logic by your API. The request to your API is in the following format:

POST https://your-api.com/endpoint

{
    "type": "microsoft.graph.authenticationEvent.tokenIssuanceStart",
    "source": "/tenants/<Your tenant GUID>/applications/<Your Test Application App Id>",
    "data": {
        "@odata.type": "microsoft.graph.onTokenIssuanceStartCalloutData",
        "tenantId": "<Your tenant GUID>",
        "authenticationEventListenerId": "<GUID>",
        "customAuthenticationExtensionId": "<Your custom extension ID>",
        "authenticationContext": {
            "correlationId": "<GUID>",
            "client": {
                "ip": "30.51.176.110",
                "locale": "en-us",
                "market": "en-us"
            },
            "protocol": "OAUTH2.0",
            "clientServicePrincipal": {
                "id": "<Your Test Applications servicePrincipal objectId>",
                "appId": "<Your Test Application App Id>",
                "appDisplayName": "My Test application",
                "displayName": "My Test application"
            },
            "resourceServicePrincipal": {
                "id": "<Your Test Applications servicePrincipal objectId>",
                "appId": "<Your Test Application App Id>",
                "appDisplayName": "My Test application",
                "displayName": "My Test application"
            },
            "user": {
                "companyName": "Casey Jensen",
                "createdDateTime": "2016-03-01T15:23:40Z",
                "displayName": "Casey Jensen",
                "givenName": "Casey",
                "id": "90847c2a-e29d-4d2f-9f54-c5b4d3f26471", // Client ID representing the Microsoft Entra authentication events service
                "mail": "casey@contoso.com",
                "onPremisesSamAccountName": "caseyjensen",
                "onPremisesSecurityIdentifier": "<Enter Security Identifier>",
                "onPremisesUserPrincipalName": "Casey Jensen",
                "preferredLanguage": "en-us",
                "surname": "Jensen",
                "userPrincipalName": "casey@contoso.com",
                "userType": "Member"
            }
        }
    }
}

The REST API response format which Azure expects is in the following format, where the claims DateOfBirth and CustomRoles are returned to Azure:

{
    "data": {
        "@odata.type": "microsoft.graph.onTokenIssuanceStartResponseData",
        "actions": [
            {
                "@odata.type": "microsoft.graph.tokenIssuanceStart.provideClaimsForToken",
                "claims": {
                    "DateOfBirth": "01/01/2000",
                    "CustomRoles": [
                        "Writer",
                        "Editor"
                    ]
                }
            }
        ]
    }
}

When a B2B user from Fabrikam organization authenticates to Contoso's organization, the request payload sent to the REST API has the user element in the following format:

"user": {
    "companyName": "Fabrikam",
    "createdDateTime": "2022-07-15T00:00:00Z",
    "displayName": "John Wright",
    "id": "00aa00aa-bb11-cc22-dd33-44ee44ee44ee",
    "mail": "johnwright@fabrikam.com",
    "preferredDataLocation": "EUR",
    "userPrincipalName": "johnwright_fabrikam.com#EXT#@contoso.onmicrosoft.com",
    "userType": "Guest"
}

Supported data types

The following table shows the data types supported by Custom claims providers for the token issuance start event:

Data type	Supported
String	True
String array	True
Boolean	False
JSON	False

Claim size limitations

The maximum claim size that a claims provider can return is limited to 3KB. This is the sum of all the key and value pairs returned by the REST API.

Claims mapping policy

In Microsoft Entra ID, a claims mapping policy modifies the claims emitted in tokens issued for specific applications. It includes claims from your custom claims provider, and issuing them into the token.

{
    "ClaimsMappingPolicy": {
        "Version": 1,
        "IncludeBasicClaimSet": "true",
        "ClaimsSchema": [{
            "Source": "CustomClaimsProvider",
            "ID": "dateOfBirth",
            "JwtClaimType": "birthdate"
        },
        {
            "Source": "CustomClaimsProvider",
            "ID": "customRoles",
            "JwtClaimType": "my_roles"
        },
        {
            "Source": "CustomClaimsProvider",
            "ID": "correlationId",
            "JwtClaimType": "correlation_Id"
        },
        {
            "Source": "CustomClaimsProvider",
            "ID": "apiVersion",
            "JwtClaimType": "apiVersion"
        },
        {
            "Value": "tokenaug_V2",
            "JwtClaimType": "policy_version"
        }]
    }
}

The ClaimsSchema element contains the list of claims to be mapped with the following attributes:

Source describes the source of the attribute, the CustomClaimsProvider. Note, the last element contains a fixed value with the policy version, for testing purposes. Thus, the source attribute is omitted.
ID is the name of the claims at it returns from the Azure Function you created.

Important

The ID attribute's value is case sensitive. Make sure you type the claim name exactly as it returned by the Azure Function.
JwtClaimType is an optional name of claim in the emitted token for OpenID Connect app. It allows you to provide a different name that returns in the JWT token. For example, if the API response has an ID value of dateOfBirth, it can be emitted as birthdate in the token.

Once you create your claims mapping policy, the next step is to upload it to your Microsoft Entra tenant. Use the following claimsMappingPolicy Graph API in your tenant.

Important

The definition element should be an array with a single string value. The string should be the stringified and escaped version of your claims mapping policy. You can use tools like https://jsontostring.com/ to stringify your claims mapping policy.

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