Update api documentation

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

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

**Priority**: Low/Medium

Start by locating the middleware implementation and the API documentation entry points in the repository. Define the encryption configuration and sensible defaults before changing behavior, then update the API documentation to match. Done means middleware encryption is configurable, defaults are documented, and the relevant checks pass.

Written by the indexing model from the issue text.