Delegation Tokens

With the latest Auth0 authentication pipeline, delegation tokens should not be used to exchange an ID token issued to one client for a new one issued to a different client, or to get a new ID token. For more information refer to Introducing OIDC Conformant Authentication > Delegation.

A delegation token should be obtained and used when a client program needs to call the API of an Application Addon, such as Firebase or SAP, registered and configured in Auth0, in the same tenant as the calling program.

Given an existing token, this endpoint will generate a new token signed with the target client's secret. This is used to flow the identity of the user from the application to an API.

The type of the delegation token will vary depending on the by provider. For example, if issued for Azure Blob Storage, it will be a SAS (Shared Access Signature). If it is for the Firebase Addon, it will be a JWT.

How to get a delegation token

The id_token for an authenticated user can be used with the Delegation endpoint to request a delegation token for a particular target. The target can be an application Addon configured in Auth0. The Addons for which this can be done are those that are not SAML or WS-Fed Addons and the Addon must be configured in Auth0 with secrets obtained from the Addon service, such as Firebase. Instructions for setting up the secrets are available from the Addon configuration page for each Addon. The secrets are used to sign the delegation token so that the Addon API can validate and trust the token.

The delegation endpoint allows the setting of several parameters which will govern the contents of the delegation token, including the target, the scope, the API to be called (api_type) and an additional free-form area for additional parameters.

See the Delegation endpoint for more information.

Auth0.js Example

For an example on how to get a new token for an addon that you have activated, using Auth0.js, refer to Delegation Token Request. Note that this example is for version 7 of the Auth0.js library; delegation is not supported in version 8 of Auth0.js.

Validity Period and Termination

The validity period and the ability to revoke a delegation token, varies by individual Addon. The documentation available from the provider of any Addon API should be consulted for further information.

Using Delegation Tokens with Public Clients

There is an important caveat to note when using the delegation endpoint with Public Clients.

If you call the Token endpoint from a Public Client, the id_token will be forcibly signed using RS256, even if the JsonWebToken Signature Algorithm in the Client settings is configured as HS256.

If you then subsequently call the delegation endpoint with that id_token, it will fail if the Client's JsonWebToken Signature Algorithm was configured as HS256. This is because delegation performs validation according to the Client's settings, but the id_token was issued with a different algorithm because of the forced algorithm change.

It is therefore important that if you intend to use delegation with a Public Client, that you configure the JsonWebToken Signature Algorithm of your client as RS256.

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