Article Contents

Overview
Barcode Formats
Supported Formats by Platform
Format Specifications
QR Code
Aztec
PDF417
Code 128
Barcode Recommendations
Apple Wallet Barcode Configuration
JSON Structure
Format Values
Encoding Options
Multiple Barcodes
watchOS Considerations
Google Wallet Barcode Configuration
JSON Structure
Type Values
Rotating Barcodes
NFC Specifications
Platform Comparison
Requirements
JSON Configuration
encryptionPublicKey Format
Express Mode
Requirements
Compatible Terminal Providers
Configuration
Smart Tap Behavior
Scanner Recommendations
For Wallet Passes
Testing Considerations
Security Considerations
Barcode Security
NFC Security
Common Mistakes
Sources

Technical Reference

Barcode & NFC Reference

Daniel Baudino

Updated January 20, 2026

TL;DR: Technical specifications for barcodes and NFC in Apple Wallet and Google Wallet passes.

Both platforms support QR, Aztec, PDF417, and Code 128
Use 2D barcodes (QR, Aztec, PDF417) for smartphone screens
NFC requires Apple/Google certification and compatible terminals
Apple: Value Added Services (VAS) protocol
Google: Smart Tap protocol
Rotating barcodes supported for enhanced security

Overview

This reference covers barcode formats and NFC specifications for wallet passes. Both platforms support similar barcode types, but NFC implementations differ significantly.

Key distinction: Barcodes work with any compatible scanner. NFC requires certified terminals and approved credentials.

Barcode Formats

Supported Formats by Platform

Format	Apple Wallet	Google Wallet	Type	Best For
QR Code	Yes	Yes	2D	General purpose, high capacity
Aztec	Yes	Yes	2D	Compact, no quiet zone needed
PDF417	Yes	Yes	2D	High density, boarding passes
Code 128	Yes (iOS 9+)	Yes	1D	Legacy systems

Format Specifications

Specification	Value
Data capacity	4,296 alphanumeric chars
Error correction	L (7%), M (15%), Q (25%), H (30%)
Quiet zone	4 modules minimum
Best for	General purpose, URLs, large payloads

Specification	Value
Data capacity	3,832 alphanumeric chars
Error correction	5% to 95% configurable
Quiet zone	Not required
Best for	Space-constrained, mobile ticketing

Specification	Value
Data capacity	1,850 alphanumeric chars
Error correction	9 levels (0-8)
Structure	Multi-row stacked
Best for	Boarding passes, IDs, high-density data

Specification	Value
Data capacity	Variable (ASCII 128)
Type	Linear (1D)
watchOS support	No (Apple)
Best for	Legacy scanner compatibility

Barcode Recommendations

Use 2D barcodes (QR, Aztec, PDF417) for wallet passes: - Better scanning on LCD screens - Higher data capacity - More reliable in real-world conditions - Supported by optical scanners

Avoid 1D barcodes unless required: - Laser scanners struggle with LCD screens - Lower data capacity - More susceptible to damage/distortion

Apple Wallet Barcode Configuration

JSON Structure

json

{
  "barcodes": [
    {
      "format": "PKBarcodeFormatQR",
      "message": "PASS123456789",
      "messageEncoding": "iso-8859-1",
      "altText": "PASS123456789"
    }
  ]
}

Format Values

Format Constant	Barcode Type
PKBarcodeFormatQR	QR Code
PKBarcodeFormatAztec	Aztec
PKBarcodeFormatPDF417	PDF417
PKBarcodeFormatCode128	Code 128

Encoding Options

Encoding	Use Case
iso-8859-1	Most scanners (recommended)
utf-8	Unicode support

Note: Most barcode scanners use ISO 8859-1 or Windows-1252 encoding. Unicode is poorly supported by scanning systems.

Multiple Barcodes

iOS 9+ uses the barcodes array. For backwards compatibility with iOS 8:

json

{
  "barcode": {
    "format": "PKBarcodeFormatQR",
    "message": "PASS123456789",
    "messageEncoding": "iso-8859-1"
  },
  "barcodes": [
    {
      "format": "PKBarcodeFormatQR",
      "message": "PASS123456789",
      "messageEncoding": "iso-8859-1"
    }
  ]
}

watchOS Considerations

Code 128 not supported
Rectangular barcodes rotated to portrait
Barcode placed at bottom of pass

Google Wallet Barcode Configuration

JSON Structure

json

{
  "barcode": {
    "type": "QR_CODE",
    "value": "PASS123456789",
    "alternateText": "PASS123456789"
  }
}

Type Values

Type Constant	Barcode Type
QR_CODE	QR Code
AZTEC	Aztec
PDF_417	PDF417
CODE_128	Code 128
TEXT_ONLY	No barcode, text display

Rotating Barcodes

Google Wallet supports rotating barcodes for enhanced security:

Supported Formats	Not Supported
QR_CODE	AZTEC
PDF_417	CODE_128

Behavior: - Barcode pattern refreshes every ~60 seconds - Screenshots become invalid quickly - Requires backend integration for validation

NFC Specifications

Platform Comparison

Aspect	Apple Wallet	Google Wallet
Protocol	Value Added Services (VAS)	Smart Tap
Certification	Required from Apple	Required from Google
Payload size	64 bytes	Varies
Express Mode	Supported	N/A
Hands-free	Yes (with Express Mode)	Yes (with Smart Tap)

Apple Wallet NFC (VAS)

NFC Certificate — Apply through Apple Developer Program (~4 weeks approval)
Compatible terminal — VAS protocol support required
Enhanced Passbook certificate — Included in NFC-enabled pass signing

json

{
  "nfc": {
    "message": "CUSTOMER_ID_12345",
    "encryptionPublicKey": "MDkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDIgAC..."
  }
}

Requirement	Specification
Format	Base64-encoded X.509 SubjectPublicKeyInfo
Key type	ECDH public key
Curve	P256 (secp256r1)
Form	Compressed (x-coordinate only)

Generation command: bash openssl ec -in private.pem -pubout -conv_form compressed

Express Mode allows NFC passes to work without unlocking the device: - Must be enabled by user - Works with Face ID, Touch ID, or passcode devices - Ideal for high-throughput access control

Google Wallet NFC (Smart Tap)

Smart Tap certification — Required from Google
Compatible terminal — From certified provider
Redemption Issuer configuration — Collector ID and keys

Advanced Card Systems Ltd.
Contactless Technologies B.V.
Intercard Inc.
Ubiquiti Inc.
UIC Payworld Inc.

Passes must include redemptionIssuers property in the class:

json

{
  "redemptionIssuers": ["1234567890123456789"]
}

Only one pass transmitted per tap
If multiple eligible passes, user sees selection carousel
Terminal authenticates using collector keys
Data transmitted in encrypted form

Scanner Recommendations

For Wallet Passes

Scanner Type	LCD Compatibility	Recommendation
Optical (2D imager)	Excellent	Recommended
Camera-based	Good	Acceptable
Laser	Poor	Not recommended

Testing Considerations

Multiple angles — Test scanning at various tilts
Brightness levels — Low/high screen brightness
Distance — Near and far scanning range
Speed — Fast scan scenarios (gate throughput)

Security Considerations

Barcode Security

Risk	Mitigation
Screenshot sharing	Rotating barcodes
Barcode copying	One-time use validation
Replay attacks	Time-stamped payloads

NFC Security

Feature	Purpose
Encrypted transmission	Prevents interception
Terminal authentication	Prevents rogue readers
Certificate requirements	Limits abuse
Payload encryption	Protects sensitive data

Common Mistakes

Using laser scanners — Most cannot read LCD screens reliably.

Choosing 1D barcodes — Lower reliability and capacity for mobile.

Skipping NFC certification — Passes won't work without proper setup.

Ignoring encoding — Wrong encoding causes scan failures.

No fallback — NFC fails, no barcode backup visible.

Sources

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Barcode & NFC Reference

Overview

Barcode Formats

Supported Formats by Platform

Format Specifications

Barcode Recommendations

Apple Wallet Barcode Configuration

JSON Structure

Format Values

Encoding Options

Multiple Barcodes

watchOS Considerations

Google Wallet Barcode Configuration

JSON Structure

Type Values

Rotating Barcodes

NFC Specifications

Platform Comparison

Apple Wallet NFC (VAS)

Google Wallet NFC (Smart Tap)

Scanner Recommendations

For Wallet Passes

Testing Considerations

Security Considerations

Barcode Security

NFC Security

Common Mistakes

Sources

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