HCE tutorial

HCE tutorial
A simple wallet
By Jensen

Outline
• Running environment
• APDU format
• Registration HCE service
• Registration AID
• APDU command list
• Applet AID define
• APDU command define
• processCommandApdu
• Card Reader side, APDU define
• Card Reader side, send APDU
• Seek-for-android

Running environment
• Card reader side
• Java 8 (jre1.8.0.25)
• Android side
• Android 4.4.2
• Infocus M510
• IDE
• Eclipse 4.4.1
• Code download
• https://github.com/jensen0915/HCE_simple_wallet
• https://github.com/jensen0915/HCE_simple_wallet_carder

Application protocol data unit (APDU) format
Source: http://en.wikipedia.org/wiki/Smart_card_application_protocol_data_unit

Registration HCE service
<service
android:name="hce_demo.MyHostApduService"
android:exported="true"
android:permission="android.permission.BIND_NFC_SERVICE" >
<intent-filter>
<action android:name="android.nfc.cardemulation.action.HOST_APDU_SERVICE" />
</intent-filter>
<meta-data
android:name="android.nfc.cardemulation.host_apdu_service"
android:resource="@xml/apduservice" />
</service>

Registration AID
<host-apdu-service xmlns:android="http://schemas.android.com/apk/res/android"
android:description="@string/servicedesc"
android:requireDeviceUnlock="false" >
<aid-group
android:category="other"
android:description="@string/aiddescription" >
<aid-filter android:name="F0394148148100" />
</aid-group>
</host-apdu-service>

APDU command list
• Applet AID
• Add money
• Sub money
• Check balance

Applet AID define
private static final byte[] AID_SELECT_APDU = {
(byte) 0x00, // CLA (class of command)
(byte) 0xA4, // INS (instruction); A4 = select
(byte) 0x04, // P1 (parameter 1) (0x04: select by name)
(byte) 0x00, // P2 (parameter 2)
(byte) 0x07, // LC (length of data)
(byte) 0xF0, (byte) 0x39, (byte) 0x41, (byte) 0x48, (byte) 0x14, (byte) 0x81, (byte) 0x00,
(byte) 0x00 // LE (max length of expected result, 0 implies 256)
};

APDU command define
private boolean selectAddMoneyApdu(byte[] apdu) {
//(byte) 0x80, // CLA
//(byte) 0x01, // INS
//(byte) 0x00, // P1
//(byte) 0x00, // P2
return apdu.length >= 2 && apdu[0] == (byte) 0x80 && apdu[1] == (byte) 0x01
&& apdu[2] == (byte) 0x00 && apdu[3] == (byte) 0x00;
}
private boolean selectDebitApdu(byte[] apdu) {
//(byte) 0x80, // CLA
//(byte) 0x02, // INS
//(byte) 0x00, // P1
//(byte) 0x00, // P2
}

APDU command define (cont.)
private boolean selectCheckBalanceApdu(byte[] apdu) {
//(byte) 0x80, // CLA
//(byte) 0x03, // INS
//(byte) 0x00, // P1
//(byte) 0x00, // P2
}

processCommandApdu
@Override
public byte[] processCommandApdu(byte[] apdu, Bundle extras) {
String inboundApduDescription;
byte[] responseApdu;
if (Arrays.equals(AID_SELECT_APDU, apdu)) {
inboundApduDescription = "Application selected";
Log.i("HCEDEMO", inboundApduDescription);
byte[] answer = new byte[2];
answer[0] = (byte) 0x90;
responseApdu = answer;
return responseApdu;
}

else if (selectAddMoneyApdu(apdu)) {
Log.i("HCEDEMO", "ADD selected");
int length = apdu[4];
System.out.println("length = " + length);
walletBalance = (byte)(walletBalance + apdu[5]);
answer[2] = walletBalance;
}
else if (selectDebitApdu(apdu)) {
Log.i("HCEDEMO", "Debit selected");
int length = apdu[4];
System.out.println("length = " + length);
// balance can not be negative
if ( (byte)( (byte) walletBalance - apdu[5]) < (byte) 0 ) {
}

else if (selectCheckBalanceApdu(apdu)) {
Log.i("HCEDEMO", "check balance
selected");
answer[2] = walletBalance;
}
else {
Log.i("HCEDEMO", "Unknown command");
answer[0] = (byte) 0x6F;
}
}

Card Reader side, APDU define
//wallet
public static byte[] SelectAID = new byte[]{(byte) 0x00, (byte) 0xA4, (byte) 0x04, (byte) 0x00,
(byte) 0x07,
(byte) 0xF0, (byte) 0x39, (byte) 0x41, (byte) 0x48, (byte) 0x14, (byte) 0x81, (byte) 0x00, (byte)
0x00
};
public static byte[] addMoney = new byte[]{(byte) 0x80, (byte) 0x01, (byte) 0x00, (byte) 0x00,
(byte) 0x01, (byte) 0x64};
public static byte[] subMoney = new byte[]{(byte) 0x80, (byte) 0x02, (byte) 0x00, (byte) 0x00,
(byte) 0x01, (byte) 0x34};
public static byte[] checkBalance = new byte[]{(byte) 0x80, (byte) 0x03, (byte) 0x00, (byte)
0x00};

Card Reader side, send APDU
public static void main(String[] args) throws UnsupportedEncodingException {
TerminalFactory terminalFactory = TerminalFactory.getDefault();
try {
for (CardTerminal terminal : terminalFactory.terminals().list()) {
System.out.println(terminal.getName());
try {
Card card = terminal.connect("*");
CardChannel channel = card.getBasicChannel();
System.out.println("SelectAID ");
CommandAPDU command = new CommandAPDU(SelectAID);
ResponseAPDU response = channel.transmit(command);
byte recv[] = response.getBytes();
for (int i = 0; i < recv.length; i++) {
System.out.print(String.format("%02X", recv[i]));
}
System.out.println("");
}

Demo
• Expectation output
SelectAID
9000
addMoney
900028
subMoney
010200
check balance
900028

Seek-for-android
https://code.google.com/p/seek-for-android/

Install Open Mobile API
• The Eclipse development environment needs to be configured in
order to use the official SDK from Google as described in the Google
documentation. In addition, the SDK needs to have access to the
Open Mobile API addon package.
https://code.google.com/p/seek-for-android/wiki/UsingSmartCardAPI

AndroidManifest.xml
• <application
• Add
<uses-library android:name="org.simalliance.openmobileapi"
android:required="true" />
• <manifest
• Add
<uses-permission
android:name="org.simalliance.openmobileapi.SMARTCARD" />

Register SEService
• Abstract function

Binding SEService
• protected void onCreate(Bundle savedInstanceState) {

Connection to SIM (secure element)

Face a problem
• Execution result
• Reader openSession: service session is null.
• Unfortunately, we guess current open mobile API that doesn’t
support HCE.

HCE tutorial

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