Verification Channels

Choose the right communication channel for your mDL verification use case.

The mDL SDK supports three verification channels as defined by ISO 18013-5. Each channel has different characteristics suited to various use cases.

Channel	Best For	Range	Setup Complexity
QR Code	Most scenarios, easy UX	Visual range	Low
NFC	Quick tap verification	< 4cm	Medium
Bluetooth LE	Hands-free, larger data	~10m	Medium

QR Code Verification

QR code verification is the most common and easiest to implement. Your app displays a QR code that the mDL holder scans with their wallet app, which then responds with their credential data.

When to Use

General-purpose age or identity verification
Retail and hospitality environments
When NFC/BLE hardware isn't available
Remote or contactless verification

Implementation

Tip: For QR code generation, you can use libraries like ZXing or ML Kit Barcode Scanning.

NFC Verification

NFC verification allows the holder to tap their phone against your device. This provides a quick, intuitive experience similar to contactless payments.

When to Use

Point-of-sale terminals
Access control systems
Quick repeated verifications
When both devices have NFC

Check NFC Availability

Implementation

Bluetooth LE Verification

Bluetooth Low Energy (BLE) verification allows wireless communication over a longer range than NFC. This is useful for hands-free scenarios or when transferring larger amounts of data.

When to Use

Hands-free verification scenarios
When requesting large data like photos
Vehicle-based verification (drive-through)
When NFC isn't practical

Check BLE Availability

Implementation

Important: BLE verification requires location permissions on Android. Make sure to request ACCESS_FINE_LOCATION at runtime before starting BLE verification.

Channel Selection Best Practices

Consider these factors when choosing a verification channel:

Factor	QR	NFC	BLE
Device requirements	Camera only	NFC hardware	BLE hardware
User action	Scan QR code	Tap devices	Proximity
Data transfer speed	Limited	Moderate	Fast
Power consumption	Low	Very low	Moderate
Implementation effort	Simple	Moderate	Moderate

Multi-Channel Support

Your app can support multiple channels and let users choose, or automatically select based on device capabilities: