Add unit tests for models

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

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

**Priority**: Low/Medium

First reconcile the title's request for unit tests with the body’s proposal for configurable encryption, then locate the relevant services, models, configuration, and existing tests. Define the supported encryption behavior and sensible defaults before implementation; done should include tests covering configuration and encryption behavior.

Written by the indexing model from the issue text.