Client secret hashed in source identity provider

[dan]

We're migrating from an identity provider (Duende) that hashes the client secret when the client credentials grant is used.

How can we migrate these secrets to FusionAuth entities?

[dan]

No perfect options, but a few workarounds possible

• a connector-like proxy which would intercept Client Credentials requests from their customers and use business logic to validate the client secret against the stored Duende hash.
• stand up a simple proxy in front of the Duende that logs the plaintext client secrets for a period of time before migration (protect these logs of course)
• go to each client and ask them to use a new FusionAuth specific client secret (analogous to resetting user passwords)

More details on the first option. It requires these steps/prereqs:

FusionAuth Entities Setup

• The customer should create new FusionAuth Entities that correlate to the Client ID of all APIs and services currently associated with Duende. For now, let FusionAuth generate a random Client Secret.
• Custom Attribute for Migration: Store a custom attribute such as migration: false on entity.data for all newly created Entities.

Migration Steps

• API/Service Requests Token: The API or service calls Duende's token endpoint.
• Proxy Interception: The customer's proxy intercepts the client credentials request and searches FusionAuth Entities to find the matching Entity by Client ID.
• Migration Check: Use an if/else logic to check if migration: false exists for this client ID. If so, the proxy service proceeds with the client credentials request to Duende using the Client ID and Secret (in plain text).
• JWT Validation: If Duende responds with a JWT, this confirms the Client Secret is correct. The proxy service discards Duende's JWT and then calls the Entity API to update the correct Client Secret and set migration: true on the entity.data object.
• Complete Migration: The proxy service calls FusionAuth's token endpoint to complete the Client Credentials grant. The proxy service then returns a JWT to the end customer’s API/service, migration is complete.

Which of these make sense depend on how many clients you have, your dev teams bandwidth, and your security posture.