External authentication for S3 credentials — supported or planned?

[abdeldjalil-fellah]

We're evaluating RustFS as an update-distribution server. Our users live in an external licensing service, and we'd like RustFS to validate S3 access-key/secret auth against it instead of the internal IAM store.

The docs cover internal IAM and OIDC/STS, but that doesn't apply to plain SigV4 key-pair auth from S3 clients (rclone, SDKs). Is there — or is there planned — an external-auth hook, similar to MinIO's identity plugin or SFTPGo's external-auth hook (HTTP endpoint / executable called per login)?

Current workaround is mirroring users into RustFS via the admin API; a hook would remove the need for two synced user stores.