BLE Security FAQ

Quick, practical answers for the most common BLE lab issues and misconceptions.

Pairing vs bonding: what is the difference?

Pairing negotiates keys now; bonding stores those keys so future connections can re-use trusted context.

Why do I get “insufficient authentication” or “insufficient encryption”?

The characteristic likely requires a stronger security state than your current connection. Pair correctly, ensure encryption is active, then retry the operation.

Why do services/characteristics appear to change?

Some devices expose additional functionality only after secure state is established. Also watch for client-side GATT caching issues.

Why do writes appear successful but device behavior does not change?

• Wrong value format or endian order
• Missing prerequisite command sequence
• Notification/indication not enabled for state updates
• Device rejects update internally without obvious client error

Can I read all BLE traffic by default?

No. Advertising is easy to observe, but connected encrypted traffic has stricter practical limits.

Best troubleshooting order?

1. Confirm signal stability and reconnect reliability.
2. Pair/bond intentionally and verify security state.
3. Re-discover services post-pairing.
4. Test one characteristic at a time with logging.
5. Cross-check behavior with a known-good client app.