tangem-sdk-react-native

The Tangem card is a self-custodial hardware wallet for blockchain assets. The main functions of Tangem cards are to securely create and store a private key from a blockchain wallet and sign blockchain transactions. The Tangem card does not allow users to import/export, backup/restore private keys, thereby guaranteeing that the wallet is unique and unclonable.

• Getting Started
  • Requirements
  • Installation
  • iOS Notes
  • Android Notes
• Usage
  • Scan card
  • Sign
  • Wallet
    • Create Wallet
    • Purge Wallet
  • Authentication
    • Passcode
    • AccessCode
    • Reset User Codes
  • NFC Status

Getting Started

Requirements

iOS

iOS 13+ (CoreNFC is required), Xcode 11+

Android

Android with minimal SDK version of 21 and a device with NFC support

Installation

npm install tangem-sdk-react-native

Android Notes

Add the following intent filters and metadata tag to your app AndroidManifest.xml

<intent-filter>
    <action android:name="android.nfc.action.NDEF_DISCOVERED"/>
    <category android:name="android.intent.category.DEFAULT"/>
</intent-filter>

<intent-filter>
    <action android:name="android.nfc.action.TECH_DISCOVERED"/>
</intent-filter>

<meta-data android:name="android.nfc.action.TECH_DISCOVERED" android:resource="@xml/nfc_tech_filter" />

Create the file android/src/main/res/xml/nfc_tech_filter.xml and add the following content:

<resources>
   <tech-list>
       <tech>android.nfc.tech.IsoDep</tech>
       <tech>android.nfc.tech.Ndef</tech>
       <tech>android.nfc.tech.NfcV</tech>
   </tech-list>
</resources>

Example AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
         package="com.reactnativenfcdemo"
         android:versionCode="1"
         android:versionName="1.0">

   <uses-permission android:name="android.permission.INTERNET" />
   <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
   <uses-permission android:name="android.permission.NFC" />

<uses-sdk
           android:minSdkVersion="16"
           android:targetSdkVersion="22" />

<application
           android:name=".MainApplication"
           android:allowBackup="true"
           android:label="@string/app_name"
           android:icon="@mipmap/ic_launcher"
           android:theme="@style/AppTheme">
<activity
               android:name=".MainActivity"
               android:screenOrientation="portrait"
               android:label="@string/app_name"
               android:launchMode="singleTask"
               android:configChanges="keyboard|keyboardHidden|orientation|screenSize"
               android:windowSoftInputMode="adjustResize">

           <intent-filter>
               <action android:name="android.intent.action.MAIN" />
               <category android:name="android.intent.category.LAUNCHER" />
           </intent-filter>

           <intent-filter>
               <action android:name="android.nfc.action.NDEF_DISCOVERED"/>
               <category android:name="android.intent.category.DEFAULT"/>
           </intent-filter>

           <intent-filter>
               <action android:name="android.nfc.action.TECH_DISCOVERED"/>
           </intent-filter>

           <meta-data android:name="android.nfc.action.TECH_DISCOVERED" android:resource="@xml/nfc_tech_filter" />

       </activity>
       <activity android:name="com.facebook.react.devsupport.DevSettingsActivity" />

   </application>

</manifest>

iOS Notes

1. Add Swift Header Search Path to your app by following this steps:

• Open ios/YourAppName.xcodeproj in Xcode
• Right-click on Your App Name in the Project Navigator on the left, and click New File…
• Create a single empty Swift file to the project (make sure that Your App Name target is selected when adding)
• When Xcode asks, press Create Bridging Header and do not remove Swift file then.

2. Configure your app to detect NFC tags. Turn on Near Field Communication Tag Reading under the Capabilities tab for the project’s target (see Add a capability to a target). Note. When you adding Near Field Communication Tag Reading capability, Xcode generates entries in *.entitlement file. You should check that there are only the Tag string in formats array. Otherwise AppStore will reject your build when you try to upload it.

<key>com.apple.developer.nfc.readersession.formats</key>
<array>
    <string>TAG</string>
</array>

3. Add the NFCReaderUsageDescription key as a string item to the Info.plist file. For the value, enter a string that describes the reason the app needs access to the device’s NFC reader:

<key>NFCReaderUsageDescription</key>
<string>Some reason</string>

4. In the Info.plist file, add the list of the application identifiers supported in your app to the ISO7816 Select Identifiers (AIDs) information property list key. The AIDs of Tangem cards are: A000000812010208 and D2760000850101.

<key>com.apple.developer.nfc.readersession.iso7816.select-identifiers</key>
<array>
    <string>A000000812010208</string>
    <string>D2760000850101</string>
</array>

5. To prevent customers from installing apps on a device that does not support the NFC capability, add the following to the Info.plist code (Optional):

<key>UIRequiredDeviceCapabilities</key>
<array>
    <string>nfc</string>
</array>

Usage

Tangem SDK is a self-sufficient solution that implements a card abstraction model, methods of interaction with the card and interactions with the user via UI.

The easiest way to use the SDK is to call basic methods. The basic method performs one or more operations and, after that, calls completion block with success or error.

When calling basic methods, there is no need to show the error to the user, since it will be displayed on the NFC popup before it's hidden.

Start/Stop Session

Method RNTangemSdk.startSession() will allow to pass customized SDK config for every session operations.

calling method is required before running any other method in android, calling this method will ask the user to enable the NFC in case of NFC disabled.

const config = {
  attestationMode: "offline",
  defaultDerivationPaths: "m/44'/144'/0'/0/0",
};
RNTangemSdk.startSession();

It's recommended to check for NFC status before running any other method and call this method again in case of disabled NFC

Method RNTangemSdk.stopSession() will stop NFC Manager and also clear the passed config from startSession method and it's recommended to be called to stop the session.

RNTangemSdk.stopSession();

Scan card

Method RNTangemSdk.scanCard() is needed to obtain information from the Tangem card. Optionally, if the card contains a wallet (private and public key pair), it proves that the wallet owns a private key that corresponds to a public one.

RNTangemSdk.scanCard();

Sign

Method RNTangemSdk.sign() allows you to sign one or multiple hashes. The SIGN command will return a corresponding array of signatures.

var cardId = "bb03000000000004";
var hahses = [
  "44617461207573656420666f722068617368696e67",
  "4461746120666f7220757365642068617368696e67",
];

RNTangemSdk.sign({ cardId, hashes });

Wallet

Create Wallet

Method RNTangemSdk.createWallet() will create a new wallet on the card. A key pair WalletPublicKey / WalletPrivateKey is generated and securely stored in the card.

var cardId = "bb03000000000004";

RNTangemSdk.createWallet({ cardId });

Purge Wallet

Method RNTangemSdk.purgeWallet() deletes all wallet data.

var cardId = "bb03000000000004";

RNTangemSdk.purgeWallet({ cardId });

Authentication

Set Passcode

Method RNTangemSdk.setPasscode() allows to set or change passcode on the card. Passcode protects signing and operations that can alter security parameters. Passcode may be enabled or disabled during card configuration at the factory. Also, it’s possible to prohibit removing the passcode from the card once it’s set.

var cardId = "bb03000000000004";

RNTangemSdk.setPasscode({ cardId });

Set AccessCode

Method RNTangemSdk.setAccessCode() allows to set or change acccessCode on the card. If Access code is set on the card, all commands, including Scan Card, will require to sumbit this code. So if the Access code is lost, there is no way to recover the data or even retrieve the public key. Access codes may be enabled or disabled during card configuration at the factory. Also, it’s possible to prohibit removing the access code from the card once it’s set.

var cardId = "bb03000000000004";

RNTangemSdk.setAccessCode({ cardId });

Reset User Codes

Method RNTangemSdk.resetUserCodes() resets both access code and passcode if they were set.

var cardId = "bb03000000000004";

RNTangemSdk.resetUserCodes({ cardId });

NFC Status

Get status

Method RNTangemSdk.getNFCStatus() will return current NFC Status which is supported on the device or is NFC enabled on the device.

RNTangemSdk.getNFCStatus();

Listen on events [Android]

with RNTangemSdk.addListener() you should be able to add listener on the certain events

Supported Events: NFCStateChange

const nfcListener = RNTangemSdk.addListener("NFCStateChange", (enabled) => {
  console.log(enabled);
});

// remove listener
if (nfcListener) {
  nfcListener.remove();
}