Beamio NTAG 424 Init Tool

An iOS app built with SwiftUI for production-line initialization of NTAG 424 DNA NFC tags. Supports reading UID, deriving per-card SDM keys, and writing NDEF URL templates for the Beamio SUN (Secure Unique NFC) verification flow.

Features

• Read UID: Hold your device near an NTAG 424 DNA tag to read its UID
• One-tap Init: Complete production workflow
  1. Read UID
  2. Derive per-card SDM Key from Master Key + UID via KDF
  3. Write NDEF URL template (static part of SUN verification endpoint)
• Configurable parameters: Master Key, New Key0, SUN Base URL, etc.

Requirements

• iOS 13.0+
• iPhone with NFC support (iPhone 7 or later)
• NTAG 424 DNA tags (e.g. Gototags NFC PVC Card - NTAG 424 DNA)

Configuration

Parameter	Description
K_master	16-byte HEX, used to derive per-card SDM Key
New Key0	16-byte HEX, optional, for writing Key0x00 (admin)
SUN Base URL	Static part of NDEF URL template, e.g. https://api.beamio.app/nfc/sun

Usage

1. Open the app and fill in or confirm the default configuration
2. Read UID: Tap "Read UID" and hold your device near the tag (e.g. Gototags NTAG 424 DNA card)
3. Init Card: Tap "Init Card (One-tap)" and follow the prompts to hold near the tag twice:
   • First tap: Read UID, derive Key, prepare NDEF
   • Second tap: Write NDEF URL template

Gototags NTAG 424 DNA Cards

• 全新卡：留空「当前 Key0」，直接 Init
• 已预编码卡（Gototags 出厂卡等）：填写「当前 Key0」（向厂商获取）后 Init，可覆盖为我们的 Key2/SDM/NDEF 配置

Project Structure

NDEF/
├── NDEFApp.swift      # App entry point
├── ContentView.swift  # Main UI
├── NDEFWriter.swift  # NFC read/write, KDF derivation, NDEF write logic
└── Assets.xcassets   # App assets

Technical Details

• CoreNFC: NFCTagReaderSession for UID reading, NFCNDEFReaderSession for NDEF writing
• KDF: Placeholder uses SHA256 (BEAMIO_SDM || UID || masterKey); replace with AES-CMAC for production
• NDEF: Writes Well-Known URI records; URL template format is {base}?e=&c=&m= (SDM encData/counter/cmac placeholders)

TODO

• Write Key0x00 (optional)
• Write Key0x02 = derived SDM Key
• Configure SDM (encData with UID + counter + cmac)
• Lock permissions
• Integrate NTAG 424 DNA EV2 full command set

Permissions

The app requires NFCReaderUsageDescription for reading and writing NFC tags. A system permission prompt appears on first use.

Team

CONET-Labs / Beamio