Add unit tests for store

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

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

**Priority**: Low/Medium

Start by locating the core store implementation and the existing unit-test setup. Clarify whether the intended work is to add tests, configurable encryption support, or both, then define the expected defaults and encryption behavior before implementation. Done means the agreed store behavior is covered by unit tests.

Written by the indexing model from the issue text.