Add unit tests for handlers

**Feature request**
It would be great to have encryption for middleware.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_encryption` with default `false`.

No files or test entry points are named. Start by locating the middleware handlers, their configuration parsing, and existing unit tests; clarify how encryption should work and what production behavior is expected before implementing or testing enable_encryption with a default of false.

Written by the indexing model from the issue text.