Use Cases
This section describes the real-world scenarios Arx Runa is built to handle — what a user is trying to do, how Arx Runa helps, and what security guarantees apply.
Security Tiers
Arx Runa lets you choose how strongly each vault is protected when you create it:
| Tier | What you need to unlock | Best for |
|---|---|---|
| Tier 1 | Password only | Everyday use — accessible from any device |
| Tier 2 | Password + a specific USB file | High-value data — two factors required (password + physical USB key file); opt-in recovery phrase available |
Regardless of tier, the cloud never holds your encryption keys or unencrypted files.
Use Cases
| Scenario | |
|---|---|
| Personal File Backup | Back up sensitive files to any cloud provider. Only you can read them, even if the provider is breached. |
| Cross-Device Access | Access the same vault from multiple devices. Changes sync automatically without leaking filenames or structure. |
| Hardware Key & Recovery | Use a physical USB file as a second factor. Covers what happens if the USB or password is lost, and opt-in BIP-39 recovery phrase setup and use. |
| File Sharing | Share individual files with another person securely — without sharing your password or compromising the vault. |
| Multi-Destination Backup | Back up to multiple cloud providers simultaneously. Covers mirror and accumulating modes, cloud provider migration, and backup failure recovery. |
What Each Use Case Covers
Each use case document describes:
- Who is involved and what they are trying to do
- The step-by-step flow of a successful scenario
- What can go wrong and how Arx Runa handles it
- The security properties that must hold throughout
Design traceability (for developers and reviewers)
Sub-Question Traceability
| Sub-question | Description | Covered by |
|---|---|---|
| SQ1 | Encryption standards and key management | Use case 1 |
| SQ2 | USB hardware factor in authentication | Use case 3 |
| SQ3 | Chunking and sync without metadata leakage | Use cases 1, 2 |
| SQ4 | RAM-based UI / Zero-Trace | Use case 1 |
| SQ5 | File sharing in a zero-trust system | Use case 4 |