Improve error messages in handlers

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

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

**Priority**: Low/Medium

Start by locating the authentication handlers and reading how authentication is currently configured. Define the expected configuration and sensible defaults with the maintainer; the work is done when authentication supports configurable encryption and the relevant behavior is covered by tests.

Written by the indexing model from the issue text.