Wearable Data Security: Protect User Privacy by Building a Secure Health Data Pipeline
Source: Dev.to
Why Database-Level Security Matters
In a traditional model, security logic often lives in the API. This means that a single bug in your server‑side code could expose one user’s heart‑rate data to another.
By using Row Level Security (RLS) within a platform like Supabase, you shift the gatekeeper to the database itself. This creates a secure‑by‑default environment where, even if a request bypasses the frontend, the database will reject any action that violates the user’s specific rules.
Building the Secure Pipeline
Creating a real‑time sync for wearable data (e.g., heart rate and step counts) requires a robust connection between the mobile app and the backend.
- The Backend Table – Every entry is linked to a unique
user_id. - The React Native Client – Initializes a client that uses encrypted storage to manage user sessions.
- The Real‑Time Subscription – Allows the app to listen for updates, ensuring the user sees their data the moment it is recorded by a wearable device.
Security Architecture Checklist
| Security Layer | Function | Benefit |
|---|---|---|
| User Authentication | Verifies identity via email/password. | Ensures only known users enter. |
| Row Level Security | Database‑level SQL policies. | Limits data access to the owner only. |
| Encrypted Storage | Persists sessions on the device. | Prevents local data hijacking. |
| Real‑Time Channels | Filters data streams by user ID. | Prevents data leaking across users. |
The Role of RLS Policies
The core of this security model lies in two specific SQL policies:
- SELECT policy – Ensures users can only view their own health history.
- INSERT policy – Prevents a user from maliciously adding data on behalf of someone else.
-- Example RLS policy condition
auth.uid() = user_idUsing auth.uid() = user_id acts as a mandatory filter. This approach embodies defense in depth, providing multiple layers of protection even if an API key is accidentally exposed.
Key Takeaways for Developers
- Security First – Move authorization logic from the API to the database for higher reliability.
- Real‑Time Efficiency – Use subscriptions to provide users with instant feedback on their health metrics.
- Scalable Privacy – RLS lets you manage thousands of users without increasing the complexity of your security code.
For a complete walkthrough of the code and a full report on building this pipeline, visit the WellAlly technical guide.