Consider deprecating old routes API

**Description**
Currently auth lacks proper encryption support.

**Proposed solution**
Add configurable encryption with sensible defaults.

**Priority**: Low/Medium

Start by reconciling the title's reference to the old routes API with the body’s authentication and encryption proposal. Locate the authentication and routes API entry points, then determine the supported encryption requirements and configuration boundaries. Done means the scope, defaults, and validation expectations are agreed before implementation.

Written by the indexing model from the issue text.