test adding exception info to the RuntimeException in RuntimeException

add support for BLS

.gitignore

@@ -1,8 +1,11 @@
 *.iml
 .gradle
+.vscode
 /local.properties
 .idea
 .DS_Store
 /build
 /captures
+/desktop/bin
+lib/bin
 .externalNativeBuild

LICENSE

@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
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+      on Your own behalf and on Your sole responsibility, not on behalf
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+
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+   Copyright [yyyy] [name of copyright owner]
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+
+   Unless required by applicable law or agreed to in writing, software
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+   limitations under the License.

README.md

@@ -15,7 +15,7 @@ You can import the SDK in your Gradle or Maven project using [Jitpack.io](https:
 
 ```groovy
 dependencies {
-  implementation 'com.github.status-im.status-keycard-java:android:2.1.1'
+  implementation 'com.github.status-im.status-keycard-java:android:3.0.2'
 }
 ```
 
@@ -23,6 +23,6 @@ dependencies {
 
 ```groovy
 dependencies {
-  implementation 'com.github.status-im.status-keycard-java:desktop:2.1.1'
+  implementation 'com.github.status-im.status-keycard-java:desktop:3.0.2'
 }
 ```

android/build.gradle

@@ -8,8 +8,8 @@ android {
     defaultConfig {
         minSdkVersion 19
         targetSdkVersion 28
-        versionCode 201
-        versionName "2.0.1"
+        versionCode 304
+        versionName "3.0.4"
     }
 
     compileOptions {

android/src/main/AndroidManifest.xml

@@ -4,6 +4,11 @@
 
     <uses-permission android:name="android.permission.NFC" />
     <uses-permission android:name="android.permission.INTERNET" />
-    <uses-feature android:name="android.hardware.nfc.hce" android:required="true" />
+    <uses-permission android:name="android.permission.BLUETOOTH"/>
+    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
+    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
+
+    <uses-feature android:name="android.hardware.nfc.hce" android:required="false" />
+    <uses-feature android:name="android.hardware.bluetooth_le" android:required="false"/>
 
 </manifest>

android/src/main/java/im/status/keycard/android/LedgerBLEChannel.java

@@ -0,0 +1,169 @@
+package im.status.keycard.android;
+
+import android.bluetooth.*;
+import android.content.Context;
+import im.status.keycard.io.*;
+
+import java.io.IOException;
+import java.util.UUID;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.TimeUnit;
+
+public class LedgerBLEChannel implements CardChannel {
+  final public static UUID LEDGER_UUID = UUID.fromString("13D63400-2C97-0004-0000-4C6564676572");
+  final public static UUID LEDGER_REQ_UUID = UUID.fromString("13D63400-2C97-0004-0002-4C6564676572");
+  final public static UUID LEDGER_RSP_UUID = UUID.fromString("13D63400-2C97-0004-0001-4C6564676572");
+
+  final private static int BLE_WRITE_FAILED = -1;
+  final private static int BLE_WRITE_STARTED = 0;
+  final private static int BLE_WRITE_FINISHED = 1;
+
+  final private static int BLE_TIMEOUT = 2000;
+
+
+  final private BluetoothGatt bluetoothGatt;
+  private BluetoothGattCharacteristic reqChar;
+  private boolean connected;
+  private int mtuSize;
+  private int writeStatus;
+  private LinkedBlockingQueue<byte[]> readQueue;
+
+  public LedgerBLEChannel(Context context, BluetoothDevice device, CardListener listener) {
+    this.connected = false;
+    this.mtuSize = 20;
+    this.readQueue = new LinkedBlockingQueue<>();
+    this.writeStatus = BLE_WRITE_FINISHED;
+    final CardChannel channel = this;
+
+    this.bluetoothGatt = device.connectGatt(context, false, new BluetoothGattCallback() {
+      @Override
+      public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
+        if (connected  == (newState ==  BluetoothProfile.STATE_CONNECTED)) {
+          return;
+        }
+
+        connected = newState == BluetoothProfile.STATE_CONNECTED;
+
+        if (connected) {
+          bluetoothGatt.discoverServices();
+        } else {
+          (new Thread() {
+            @Override
+            public void run() {
+              listener.onDisconnected();
+            }
+          }).start();
+        }
+      }
+
+      @Override
+      public void onServicesDiscovered(BluetoothGatt gatt, int status) {
+        BluetoothGattService service = bluetoothGatt.getService(LEDGER_UUID);
+
+        if (service == null) {
+          bluetoothGatt.disconnect();
+          connected = false;
+          return;
+        }
+
+        reqChar = service.getCharacteristic(LEDGER_REQ_UUID);
+        BluetoothGattCharacteristic rsp = service.getCharacteristic(LEDGER_RSP_UUID);
+        bluetoothGatt.setCharacteristicNotification(rsp, true);
+
+        BluetoothGattDescriptor rspDesc = rsp.getDescriptors().get(0);
+        rspDesc.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
+        gatt.writeDescriptor(rspDesc);
+      }
+
+      @Override
+      public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
+        writeStatus = status == BluetoothGatt.GATT_SUCCESS ? BLE_WRITE_FINISHED : BLE_WRITE_FAILED;
+      }
+
+      @Override
+      public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
+        reqChar.setValue(new byte[] {0x08, 0x00, 0x00, 0x00, 0x00});
+        bluetoothGatt.writeCharacteristic(reqChar);
+      }
+
+      @Override
+      public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
+        byte[] rsp = characteristic.getValue();
+
+        if (rsp[0] == 0x08) {
+          mtuSize = rsp[5];
+          (new Thread() {
+            @Override
+            public void run() {
+              listener.onConnected(channel);
+            }
+          }).start();
+          return;
+        }
+
+        readQueue.offer(rsp);
+      }
+    });
+  }
+
+  @Override
+  public APDUResponse send(APDUCommand cmd) throws IOException {
+    return LedgerUtil.send(cmd, mtuSize, false, new LedgerUtil.Callback() {
+      @Override
+      public void write(byte[] chunk) throws IOException {
+        writeStatus = BLE_WRITE_STARTED;
+        reqChar.setValue(chunk);
+        bluetoothGatt.writeCharacteristic(reqChar);
+
+        long timeout = 0;
+        while(writeStatus == BLE_WRITE_STARTED || timeout >= BLE_TIMEOUT) {
+          try {
+            Thread.sleep(10);
+            timeout += 10;
+          } catch (InterruptedException e) {
+            throw new IOException("write interrupted");
+          }
+        }
+
+        if (writeStatus != BLE_WRITE_FINISHED) {
+          throw new IOException("write operation failed");
+        }
+      }
+
+      @Override
+      public void read(byte[] chunk) throws IOException {
+        try {
+          byte[] data = readQueue.poll(BLE_TIMEOUT, TimeUnit.MILLISECONDS);
+
+          if (data == null) {
+            throw new IOException("read timeout");
+          }
+
+          System.arraycopy(data, 0, chunk, 0, Math.min(data.length, chunk.length));
+        } catch (InterruptedException e) {
+          throw new IOException("read timeout");
+        }
+      }
+    });
+  }
+
+  @Override
+  public boolean isConnected() {
+    return connected;
+  }
+
+  @Override
+  public int pairingPasswordPBKDF2IterationCount() {
+    return 10;
+  }
+
+  public void close() {
+    bluetoothGatt.close();
+  }
+
+  @Override
+  protected void finalize() throws Throwable {
+    close();
+    super.finalize();
+  }
+}

android/src/main/java/im/status/keycard/android/LedgerBLEManager.java

@@ -0,0 +1,90 @@
+package im.status.keycard.android;
+
+import android.app.Activity;
+import android.bluetooth.*;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import im.status.keycard.globalplatform.Crypto;
+import im.status.keycard.io.CardListener;
+
+import java.util.UUID;
+
+public class LedgerBLEManager {
+  private static final int REQUEST_ENABLE_BT = 1;
+
+  final private BluetoothAdapter bluetoothAdapter;
+  final private Activity activity;
+  private CardListener cardListener;
+
+  static {
+    Crypto.addBouncyCastleProvider();
+  }
+
+  public LedgerBLEManager(Activity context) {
+    this.activity = context;
+    final BluetoothManager bluetoothManager = (BluetoothManager) context.getSystemService(Context.BLUETOOTH_SERVICE);
+    this.bluetoothAdapter = bluetoothManager.getAdapter();
+  }
+
+  public void ensureBLEEnabled() {
+    if (!bluetoothAdapter.isEnabled()) {
+      Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
+      activity.startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
+    }
+  }
+
+  public void startScan(BluetoothAdapter.LeScanCallback cb) {
+    bluetoothAdapter.startLeScan(new UUID[] { LedgerBLEChannel.LEDGER_UUID}, cb);
+  }
+
+  public void stopScan(BluetoothAdapter.LeScanCallback cb) {
+    bluetoothAdapter.stopLeScan(cb);
+  }
+
+  public void connectDevice(BluetoothDevice device) {
+    if (device.getBondState() != BluetoothDevice.BOND_BONDED) {
+      final IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_BOND_STATE_CHANGED);
+      activity.registerReceiver(new BroadcastReceiver() {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+          final BluetoothDevice d = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
+          final int bondState = intent.getIntExtra(BluetoothDevice.EXTRA_BOND_STATE, -1);
+
+          if (!d.getAddress().equals(device.getAddress())) {
+            return;
+          }
+
+          if (bondState == BluetoothDevice.BOND_BONDED) {
+            activity.unregisterReceiver(this);
+            // connect/disconnect to make bond permanent
+            device.connectGatt(activity, false, new BluetoothGattCallback() {
+              @Override
+              public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
+                if (newState == BluetoothGatt.STATE_CONNECTED) {
+                  gatt.disconnect();
+                  onConnected(device);
+                }
+              }
+            });
+          }
+        }
+      }, filter);
+
+      device.createBond();
+    } else {
+      onConnected(device);
+    }
+  }
+
+  private void onConnected(BluetoothDevice device) {
+    if (cardListener != null) {
+      new LedgerBLEChannel(activity, device, cardListener);
+    }
+  }
+
+  public void setCardListener(CardListener cardListener) {
+    this.cardListener = cardListener;
+  }
+}

demo-android/build.gradle

@@ -6,8 +6,8 @@ android {
         applicationId "im.status.keycard.demo"
         minSdkVersion 19
         targetSdkVersion 28
-        versionCode 201
-        versionName "2.0.1"
+        versionCode 300
+        versionName "3.0.0"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
     }
     buildTypes {

demo-android/src/main/java/im/status/keycard/app/MainActivity.java

@@ -1,9 +1,12 @@
 package im.status.keycard.app;
 
+import android.bluetooth.BluetoothAdapter;
+import android.bluetooth.BluetoothDevice;
 import android.nfc.NfcAdapter;
 import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
 import android.util.Log;
+import im.status.keycard.android.LedgerBLEManager;
 import im.status.keycard.demo.R;
 import im.status.keycard.io.CardChannel;
 import im.status.keycard.io.CardListener;
@@ -17,6 +20,8 @@ public class MainActivity extends AppCompatActivity {
 
   private NfcAdapter nfcAdapter;
   private NFCCardManager cardManager;
+  //private LedgerBLEManager cardManager;
+  //private boolean connected;
 
   @Override
   protected void onCreate(Bundle savedInstanceState) {
@@ -24,7 +29,7 @@ public class MainActivity extends AppCompatActivity {
     setContentView(R.layout.activity_main);
     nfcAdapter = NfcAdapter.getDefaultAdapter(this);
     cardManager = new NFCCardManager();
-
+    //cardManager = new LedgerBLEManager(this);
     cardManager.setCardListener(new CardListener() {
       @Override
       public void onConnected(CardChannel cardChannel) {
@@ -159,6 +164,19 @@ public class MainActivity extends AppCompatActivity {
       }
     });
     cardManager.start();
+    /*connected = false;
+    cardManager.startScan(new BluetoothAdapter.LeScanCallback() {
+      @Override
+      public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {
+        if (connected) {
+          return;
+        }
+
+        connected = true;
+        cardManager.stopScan(this);
+        cardManager.connectDevice(device);
+      }
+    });*/
   }
 
   @Override

desktop/build.gradle

@@ -1,5 +1,19 @@
+import org.gradle.plugins.ide.eclipse.model.AccessRule
+
 apply plugin: 'java'
 apply plugin: 'maven'
+apply plugin: 'eclipse'
+
+eclipse {
+    classpath {
+        file {
+            whenMerged {
+                def jre = entries.find { it.path.contains 'org.eclipse.jdt.launching.JRE_CONTAINER' }
+                jre.accessRules.add(new AccessRule('0', 'javax/smartcardio/**'))
+            }
+        }
+    }
+}
 
 dependencies {
     compile project(':lib')

desktop/src/main/java/im/status/keycard/desktop/LedgerUSBChannel.java

@@ -3,158 +3,38 @@ package im.status.keycard.desktop;
 import im.status.keycard.io.APDUCommand;
 import im.status.keycard.io.APDUResponse;
 import im.status.keycard.io.CardChannel;
+import im.status.keycard.io.LedgerUtil;
 import org.hid4java.HidDevice;
 
-import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 
 public class LedgerUSBChannel implements CardChannel {
   private static final int HID_BUFFER_SIZE = 64;
-  private static final int LEDGER_DEFAULT_CHANNEL = 1;
-  private static final int TAG_APDU = 0x05;
   private static final int READ_TIMEOUT = 20000;
 
   private HidDevice hidDevice;
 
   public LedgerUSBChannel(HidDevice hidDevice) {
     this.hidDevice = hidDevice;
-
   }
 
   @Override
   public APDUResponse send(APDUCommand cmd) throws IOException {
-    ByteArrayOutputStream response = new ByteArrayOutputStream();
-
-    int offset = 0;
-
-    byte[] command = wrapCommandAPDU(cmd.serialize());
-
-    byte[] chunk = new byte[HID_BUFFER_SIZE];
-
-    while(offset != command.length) {
-      System.arraycopy(command, offset, chunk, 0, HID_BUFFER_SIZE);
-
-      if (hidDevice.write(chunk, HID_BUFFER_SIZE, (byte) 0x00) < 0) {
-        throw new IOException("Write failed");
+    return LedgerUtil.send(cmd, HID_BUFFER_SIZE, true, new LedgerUtil.Callback() {
+      @Override
+      public void write(byte[] chunk) throws IOException {
+        if (hidDevice.write(chunk, chunk.length, (byte) 0x00) < 0) {
+          throw new IOException("Write failed");
+        }
       }
 
-      offset += HID_BUFFER_SIZE;
-    }
-
-    byte[] responseData = null;
-
-    while ((responseData = unwrapResponseAPDU(response.toByteArray())) == null) {
-      if (hidDevice.read(chunk, READ_TIMEOUT) < 0) {
-        throw new IOException("Read failed");
+      @Override
+      public void read(byte[] chunk) throws IOException {
+        if (hidDevice.read(chunk, READ_TIMEOUT) < 0) {
+          throw new IOException("Read failed");
+        }
       }
-
-      response.write(chunk, 0, HID_BUFFER_SIZE);
-    }
-
-    return new APDUResponse(responseData);
-  }
-
-  private byte[] unwrapResponseAPDU(byte[] data) throws IOException {
-    if ((data == null) || (data.length < 7 + 5)) {
-      return null;
-    }
-
-    int sequenceIdx = 0;
-    int offset = checkResponseHeader(data, 0, sequenceIdx);
-
-    int  responseLength = ((data[offset++] & 0xff) << 8);
-    responseLength |= (data[offset++] & 0xff);
-
-    if (data.length < 7 + responseLength) {
-      return null;
-    }
-
-    ByteArrayOutputStream response = new ByteArrayOutputStream();
-
-    int blockSize = (responseLength > HID_BUFFER_SIZE - 7 ? HID_BUFFER_SIZE - 7 : responseLength);
-    response.write(data, offset, blockSize);
-    offset += blockSize;
-
-    while (response.size() != responseLength) {
-      sequenceIdx++;
-
-      if (offset == data.length) {
-        return null;
-      }
-
-      offset = checkResponseHeader(data, offset, sequenceIdx);
-
-      blockSize = (responseLength - response.size() > HID_BUFFER_SIZE - 5 ? HID_BUFFER_SIZE - 5 : responseLength - response.size());
-      if (blockSize > data.length - offset) {
-        return null;
-      }
-      response.write(data, offset, blockSize);
-      offset += blockSize;
-    }
-
-    return response.toByteArray();
-  }
-
-  private int checkResponseHeader(byte[] data, int offset, int sequenceIdx) throws IOException {
-    if (data[offset++] != (LEDGER_DEFAULT_CHANNEL >> 8)) {
-      throw new IOException("Invalid channel");
-    }
-
-    if (data[offset++] != (LEDGER_DEFAULT_CHANNEL & 0xff)) {
-      throw new IOException("Invalid channel");
-    }
-
-    if (data[offset++] != TAG_APDU) {
-      throw new IOException("Invalid tag");
-    }
-
-    if (data[offset++] != (sequenceIdx >> 8)) {
-      throw new IOException("Invalid sequence");
-    }
-
-    if (data[offset++] != (sequenceIdx & 0xff)) {
-      throw new IOException("Invalid sequence");
-    }
-    return offset;
-  }
-
-  private byte[] wrapCommandAPDU(byte[] command) {
-    ByteArrayOutputStream output = new ByteArrayOutputStream();
-
-    int sequenceIdx = 0;
-    int offset = 0;
-    writeCommandHeader(output, sequenceIdx);
-    sequenceIdx++;
-
-    output.write(command.length >> 8);
-    output.write(command.length);
-    int blockSize = (command.length > (HID_BUFFER_SIZE - 7) ? (HID_BUFFER_SIZE - 7) : command.length);
-    output.write(command, offset, blockSize);
-    offset += blockSize;
-
-    while (offset != command.length) {
-      writeCommandHeader(output, sequenceIdx);
-      sequenceIdx++;
-
-      blockSize = ((command.length - offset) > (HID_BUFFER_SIZE - 5) ? (HID_BUFFER_SIZE - 5) : (command.length - offset));
-      output.write(command, offset, blockSize);
-      offset += blockSize;
-    }
-
-    if ((output.size() % HID_BUFFER_SIZE) != 0) {
-      byte[] padding = new byte[HID_BUFFER_SIZE - (output.size() % HID_BUFFER_SIZE)];
-      output.write(padding, 0, padding.length);
-    }
-
-    return output.toByteArray();
-  }
-
-  private void writeCommandHeader(ByteArrayOutputStream output, int sequenceIdx) {
-    output.write(LEDGER_DEFAULT_CHANNEL >> 8);
-    output.write(LEDGER_DEFAULT_CHANNEL);
-    output.write(TAG_APDU);
-    output.write(sequenceIdx >> 8);
-    output.write(sequenceIdx);
+    });
   }
 
   @Override

desktop/src/main/java/im/status/keycard/desktop/LedgerUSBManager.java

@@ -11,7 +11,8 @@ public class LedgerUSBManager implements HidServicesListener {
   }
 
   private static final int VID = 0x2c97;
-  private static final int PID = 0x0001;
+  private static final int[] PIDS = { 0x0001, 0x0004 };
+
   private static final int SCAN_INTERVAL_MS = 500;
   private static final int PAUSE_INTERVAL_MS = 5000;
 
@@ -34,10 +35,13 @@ public class LedgerUSBManager implements HidServicesListener {
   public void start() {
     hidServices.start();
 
-    HidDevice hidDevice = hidServices.getHidDevice(VID, PID, null);
+    for (int pid : PIDS) {
+      HidDevice hidDevice = hidServices.getHidDevice(VID, pid, null);
 
-    if (hidDevice != null) {
-      listener.onConnected(new LedgerUSBChannel(hidDevice));
+      if (hidDevice != null) {
+        listener.onConnected(new LedgerUSBChannel(hidDevice));
+        break;
+      }
     }
   }
 
@@ -49,7 +53,7 @@ public class LedgerUSBManager implements HidServicesListener {
   public void hidDeviceAttached(HidServicesEvent event) {
     HidDevice hidDevice = event.getHidDevice();
 
-    if (hidDevice.isVidPidSerial(VID, PID, null)) {
+    if (isLedger(hidDevice)) {
       listener.onConnected(new LedgerUSBChannel(hidDevice));
     }
 
@@ -62,10 +66,18 @@ public class LedgerUSBManager implements HidServicesListener {
 
   @Override
   public void hidFailure(HidServicesEvent event) {
-    HidDevice hidDevice = event.getHidDevice();
-
-    if (hidDevice.isVidPidSerial(VID, PID, null)) {
+    if (isLedger(event.getHidDevice())) {
       listener.onDisconnected();
     }
   }
+
+  private boolean isLedger(HidDevice hidDevice) {
+    for (int pid : PIDS) {
+      if (hidDevice.isVidPidSerial(VID, pid, null)) {
+        return true;
+      }
+    }
+
+    return false;
+  }
 }

lib/src/main/java/im/status/keycard/applet/ApplicationInfo.java

@@ -118,6 +118,14 @@ public class ApplicationInfo {
    * @return the string representation of the application version
    */
   public String getAppVersionString() {
+    return getAppVersionString(appVersion);
+  }
+
+  /**
+   * A formatted application version.
+   * @return the string representation of the application version
+   */
+  static String getAppVersionString(short appVersion) {
     return (appVersion >> 8) + "." + (appVersion & 0xff);
   }
 
@@ -148,18 +156,38 @@ public class ApplicationInfo {
     return capabilities;
   }
 
+  /**
+   * Returns true if the device supports the Secure Channel capability.
+   *
+   * @return true or false
+   */
   public boolean hasSecureChannelCapability() {
     return (capabilities & CAPABILITY_SECURE_CHANNEL) == CAPABILITY_SECURE_CHANNEL;
   }
 
+  /**
+   * Returns true if the device supports the Key Management capability.
+   *
+   * @return true or false
+   */
   public boolean hasKeyManagementCapability() {
     return (capabilities & CAPABILITY_KEY_MANAGEMENT) == CAPABILITY_KEY_MANAGEMENT;
   }
 
+  /**
+   * Returns true if the device supports the Credentials Management capability.
+   *
+   * @return true or false
+   */
   public boolean hasCredentialsManagementCapability() {
     return (capabilities & CAPABILITY_CREDENTIALS_MANAGEMENT) == CAPABILITY_CREDENTIALS_MANAGEMENT;
   }
 
+  /**
+   * Returns true if the device supports the NDEF capability.
+   *
+   * @return true or false
+   */
   public boolean hasNDEFCapability() {
     return (capabilities & CAPABILITY_NDEF) == CAPABILITY_NDEF;
   }

lib/src/main/java/im/status/keycard/applet/BIP32KeyPair.java

@@ -1,6 +1,5 @@
 package im.status.keycard.applet;
 
-import org.bouncycastle.crypto.digests.KeccakDigest;
 import org.bouncycastle.math.ec.ECPoint;
 
 import javax.crypto.Mac;
@@ -171,12 +170,13 @@ public class BIP32KeyPair {
     return data;
   }
 
+  /**
+   * Returns the public key as an Ethereum address.
+   *
+   * @return the Ethereum address
+   */
   public byte[] toEthereumAddress() {
-    KeccakDigest digest = new KeccakDigest(256);
-    digest.update(publicKey, 1, (publicKey.length - 1));
-    byte[] hash = new byte[32];
-    digest.doFinal(hash, 0);
-    return Arrays.copyOfRange(hash,12, hash.length);
+    return Ethereum.toEthereumAddress(publicKey);
   }
 
   /**

lib/src/main/java/im/status/keycard/applet/BLS.java

@@ -0,0 +1,863 @@
+package im.status.keycard.applet;
+
+import java.math.BigInteger;
+import java.security.DigestException;
+import java.security.MessageDigest;
+import java.util.Arrays;
+
+public class BLS {
+  public static byte[] hash(byte[] msg) {
+    Fp[][] u = hashToField(msg, 2);
+    PointG2 q0 = isogenyMapG2(mapToCurveSimpleSWU9mod16(new Fp2(u[0][0], u[0][1])));
+    PointG2 q1 = isogenyMapG2(mapToCurveSimpleSWU9mod16(new Fp2(u[1][0], u[1][1])));
+    PointG2 r = q0.add(q1).clearCofactor();
+    return r.toByteArray(false);
+  }
+
+  public static byte[] compress(byte[] g2) {
+    return new PointG2(g2).toByteArray(true);
+  }
+
+  private BLS() {}
+
+  final static byte DST[] = {
+    (byte) 0x42, (byte) 0x4C, (byte) 0x53, (byte) 0x5F, (byte) 0x53, (byte) 0x49, (byte) 0x47, (byte) 0x5F,
+    (byte) 0x42, (byte) 0x4C, (byte) 0x53, (byte) 0x31, (byte) 0x32, (byte) 0x33, (byte) 0x38, (byte) 0x31,
+    (byte) 0x47, (byte) 0x32, (byte) 0x5F, (byte) 0x58, (byte) 0x4D, (byte) 0x44, (byte) 0x3A, (byte) 0x53,
+    (byte) 0x48, (byte) 0x41, (byte) 0x2D, (byte) 0x32, (byte) 0x35, (byte) 0x36, (byte) 0x5F, (byte) 0x53,
+    (byte) 0x53, (byte) 0x57, (byte) 0x55, (byte) 0x5F, (byte) 0x52, (byte) 0x4F, (byte) 0x5F, (byte) 0x4E,
+    (byte) 0x55, (byte) 0x4C, (byte) 0x5F, (byte) 0x2B,
+  };
+
+  final private static int L = 64;
+  final private static int M = 2;
+  final private static int SHA256_DIGEST_SIZE = 32;
+
+  final private static BigInteger P = new BigInteger("1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffaaab", 16);
+  final private static BigInteger P_MINUS_9_DIV_16 = P.pow(2).subtract(BigInteger.valueOf(9)).divide(BigInteger.valueOf(16));
+  final private static BigInteger CURVE_X = new BigInteger("d201000000010000", 16);
+
+  final private static Fp rv1 = new Fp("6af0e0437ff400b6831e36d6bd17ffe48395dabc2d3435e77f76e17009241c5ee67992f72ec05f4c81084fbede3cc09");
+  final private static Fp ev1 = new Fp("699be3b8c6870965e5bf892ad5d2cc7b0e85a117402dfd83b7f4a947e02d978498255a2aaec0ac627b5afbdf1bf1c90");
+  final private static Fp ev2 = new Fp("8157cd83046453f5dd0972b6e3949e4288020b5b8a9cc99ca07e27089a2ce2436d965026adad3ef7baba37f2183e9b5");
+  final private static Fp ev3 = new Fp("ab1c2ffdd6c253ca155231eb3e71ba044fd562f6f72bc5bad5ec46a0b7a3b0247cf08ce6c6317f40edbc653a72dee17");
+  final private static Fp ev4 = new Fp("aa404866706722864480885d68ad0ccac1967c7544b447873cc37e0181271e006df72162a3d3e0287bf597fbf7f8fc1");
+
+  final private static Fp PSI2_C1 = new Fp("1a0111ea397fe699ec02408663d4de85aa0d857d89759ad4897d29650fb85f9b409427eb4f49fffd8bfd00000000aaac");
+
+  final private static Fp2[] xnum = new Fp2[] {
+    new Fp2(new Fp("5c759507e8e333ebb5b7a9a47d7ed8532c52d39fd3a042a88b58423c50ae15d5c2638e343d9c71c6238aaaaaaaa97d6"),
+            new Fp("5c759507e8e333ebb5b7a9a47d7ed8532c52d39fd3a042a88b58423c50ae15d5c2638e343d9c71c6238aaaaaaaa97d6")),
+    new Fp2(Fp.ZERO,
+            new Fp("11560bf17baa99bc32126fced787c88f984f87adf7ae0c7f9a208c6b4f20a4181472aaa9cb8d555526a9ffffffffc71a")),
+    new Fp2(new Fp("11560bf17baa99bc32126fced787c88f984f87adf7ae0c7f9a208c6b4f20a4181472aaa9cb8d555526a9ffffffffc71e"),
+            new Fp("8ab05f8bdd54cde190937e76bc3e447cc27c3d6fbd7063fcd104635a790520c0a395554e5c6aaaa9354ffffffffe38d")),
+    new Fp2(new Fp("171d6541fa38ccfaed6dea691f5fb614cb14b4e7f4e810aa22d6108f142b85757098e38d0f671c7188e2aaaaaaaa5ed1"),
+            Fp.ZERO),    
+  };
+
+  final private static Fp2[] xden = new Fp2[] {
+    new Fp2(Fp.ZERO,
+            new Fp("1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffaa63")),
+    new Fp2(new Fp(0xc),
+            new Fp("1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffaa9f")),
+    Fp2.ONE,
+    Fp2.ZERO,    
+  };  
+
+  final private static Fp2[] ynum = new Fp2[] {
+    new Fp2(new Fp("1530477c7ab4113b59a4c18b076d11930f7da5d4a07f649bf54439d87d27e500fc8c25ebf8c92f6812cfc71c71c6d706"),
+            new Fp("1530477c7ab4113b59a4c18b076d11930f7da5d4a07f649bf54439d87d27e500fc8c25ebf8c92f6812cfc71c71c6d706")),
+    new Fp2(Fp.ZERO,
+            new Fp("5c759507e8e333ebb5b7a9a47d7ed8532c52d39fd3a042a88b58423c50ae15d5c2638e343d9c71c6238aaaaaaaa97be")),
+    new Fp2(new Fp("11560bf17baa99bc32126fced787c88f984f87adf7ae0c7f9a208c6b4f20a4181472aaa9cb8d555526a9ffffffffc71c"),
+            new Fp("8ab05f8bdd54cde190937e76bc3e447cc27c3d6fbd7063fcd104635a790520c0a395554e5c6aaaa9354ffffffffe38f")),
+    new Fp2(new Fp("124c9ad43b6cf79bfbf7043de3811ad0761b0f37a1e26286b0e977c69aa274524e79097a56dc4bd9e1b371c71c718b10"),
+            Fp.ZERO),    
+  };
+
+  final private static Fp2[] yden = new Fp2[] {
+    new Fp2(new Fp("1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffa8fb"),
+            new Fp("1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffa8fb")),
+    new Fp2(Fp.ZERO,
+            new Fp("1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffa9d3")),
+    new Fp2(new Fp(0x12),
+            new Fp("1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffaa99")),
+    new Fp2(Fp.ONE, Fp.ZERO),    
+  }; 
+
+  final private static Fp2[][] ISOGENY_COEFFICIENTS = new Fp2[][] { xnum, xden, ynum, yden };  
+
+  final private static Fp2[] FP2_ROOTS_OF_UNITY = new Fp2[] {
+    Fp2.ONE,
+    new Fp2(rv1, rv1.neg()),
+    new Fp2(Fp.ZERO, Fp.ONE),
+    new Fp2(rv1, rv1),
+    new Fp2(Fp.ONE.neg(), Fp.ZERO),
+    new Fp2(rv1.neg(), rv1),
+    new Fp2(Fp.ZERO, Fp.ONE.neg()),
+    new Fp2(rv1.neg(), rv1.neg()),
+  };
+
+  final private static Fp2[] FP2_ETAs = new Fp2[] {
+    new Fp2(ev1, ev2),
+    new Fp2(ev2.neg(), ev1),
+    new Fp2(ev3, ev4),
+    new Fp2(ev4.neg(), ev3),
+  };
+
+  private static byte[] strxor(byte[] b0, byte[] b1, int b1off) {
+    byte[] xored = new byte[b0.length];
+    for (int i = 0; i < xored.length; i++) {
+      xored[i] = (byte) (b0[i] ^ b1[i + b1off]);
+    }
+
+    return xored;
+  }
+
+  private static byte[] expandMessage(byte[] msg, byte[] DST, int len) {
+    MessageDigest md;
+    try {
+      md = MessageDigest.getInstance("SHA256");
+    } catch (Exception e) {
+      throw new RuntimeException("SHA256 missing");
+    }
+
+    int ell = (len + (SHA256_DIGEST_SIZE - 1)) / SHA256_DIGEST_SIZE;
+
+    md.update(new byte[SHA256_DIGEST_SIZE * 2]);
+    md.update(msg);
+    md.update(new byte[] { (byte) ((len >> 8) & 0xff), (byte) (len & 0xff), (byte) 0 });
+    md.update(DST);
+    byte[] b0 = md.digest();
+    byte[] b = new byte[ell * SHA256_DIGEST_SIZE];
+
+    for (int i = 0; i < ell; i++) {
+      if (i == 0) {
+        md.update(b0);
+      } else {
+        md.update(strxor(b0, b, ((i - 1) * SHA256_DIGEST_SIZE)));
+      }
+
+      md.update((byte) (i + 1));
+      md.update(DST);
+
+      try {
+        md.digest(b, (i * SHA256_DIGEST_SIZE), SHA256_DIGEST_SIZE);
+      } catch (DigestException e) {
+        throw new RuntimeException("SHA256 error");
+      }
+    }
+
+    return Arrays.copyOf(b, len);
+  }
+
+  private static Fp[][] hashToField(byte[] msg, int count) {
+    byte[] uniformBytes = expandMessage(msg, DST, count * M * L);
+    Fp[][] u = new Fp[count][M];
+    for (int i = 0; i < count; i++) {
+      for (int j = 0; j < M; j++) {
+        int off = (L * (j + (i * M)));
+        u[i][j] = new Fp(Arrays.copyOfRange(uniformBytes, off, off + L));
+      }
+    }
+    return u; 
+  }
+
+  private static PointG2 isogenyMapG2(PointG2 point) {
+    Fp2[] zPowers = new Fp2[] {point.z, point.z.square(), point.z.pow(3)};
+    Fp2[] mapped = new Fp2[] {Fp2.ZERO, Fp2.ZERO, Fp2.ZERO, Fp2.ZERO};
+
+    for (int i = 0; i < ISOGENY_COEFFICIENTS.length; i++) {
+      Fp2[] kI = ISOGENY_COEFFICIENTS[i];
+      mapped[i] = kI[3];
+      Fp2[] arr = new Fp2[] { kI[2], kI[1], kI[0] };
+      for (int j = 0; j < arr.length; j++) {
+        Fp2 kIJ = arr[j];
+        mapped[i] = mapped[i].mul(point.x).add(zPowers[j].mul(kIJ));
+      }
+  
+    }
+
+    mapped[2] = mapped[2].mul(point.y);
+    mapped[3] = mapped[3].mul(point.z);
+  
+    Fp2 z2 = mapped[1].mul(mapped[3]);
+    Fp2 x2 = mapped[0].mul(mapped[3]);
+    Fp2 y2 = mapped[1].mul(mapped[2]);
+
+    return new PointG2(x2, y2, z2);  
+  }
+
+  private static SqrtDivFp2Res sqrtDivFp2(Fp2 u, Fp2 v) {
+    Fp2 v7 = v.pow(7);
+    Fp2 uv7 = u.mul(v7);
+    Fp2 uv15 = uv7.mul(v7.mul(v));
+    Fp2 gamma = uv15.pow(P_MINUS_9_DIV_16).mul(uv7);
+
+    for (int i = 0; i < 4; i++) {
+      Fp2 candidate = FP2_ROOTS_OF_UNITY[i].mul(gamma);
+      if (candidate.square().mul(v).sub(u).isZero()) {
+        return new SqrtDivFp2Res(true, candidate);
+      }
+    }
+
+    return new SqrtDivFp2Res(false, gamma);
+  }  
+
+  private static PointG2 mapToCurveSimpleSWU9mod16(Fp2 t) {
+    Fp2 iso3a = new Fp2(new Fp(0), new Fp(240));
+    Fp2 iso3b = new Fp2(new Fp(1012), new Fp(1012));
+    Fp2 iso3z = new Fp2(new Fp(-2), new Fp(-1));
+    Fp2 t2 = t.square();
+    Fp2 iso3zt2 = iso3z.mul(t2);
+    Fp2 ztzt = iso3zt2.add(iso3zt2.square());
+    Fp2 denominator = iso3a.mul(ztzt).neg();
+    Fp2 numerator = iso3b.mul(ztzt.add(Fp2.ONE));
+
+    if (denominator.isZero()) {
+      denominator = iso3z.mul(iso3a);
+    }
+
+    Fp2 v = denominator.pow(3);
+    Fp2 u = numerator.pow(3)
+      .add(iso3a.mul(numerator).mul(denominator.square()))
+      .add(iso3b.mul(v));
+    
+    SqrtDivFp2Res sqrtCandidateOrGamma = sqrtDivFp2(u, v);
+
+    Fp2 y = null;
+
+    if (!sqrtCandidateOrGamma.success) {
+      u = iso3zt2.pow(3).mul(u);
+      Fp2 sqrtCandidateX1 = sqrtCandidateOrGamma.value.mul(t.pow(3));
+
+      for (int i = 0; i < FP2_ETAs.length; i++) {
+        Fp2 etaSqrtCanditate = FP2_ETAs[i].mul(sqrtCandidateX1);
+        if (etaSqrtCanditate.square().mul(v).sub(u).isZero()) {
+          y = etaSqrtCanditate;
+          numerator = numerator.mul(iso3zt2);
+          break;
+        }
+      }
+    } else {
+      y = sqrtCandidateOrGamma.value;
+    }
+
+    if (y == null) {
+      throw new RuntimeException("Hash to Curve - Optimized SWU failed");
+    }
+
+    if (t.sgn0() != y.sgn0()) {
+      y = y.neg();
+    }
+
+    y = y.mul(denominator);
+    return new PointG2(numerator, y, denominator);
+  }
+
+  static class Fp {
+    final static Fp ZERO = new Fp(BigInteger.ZERO);
+    final static Fp ONE = new Fp(BigInteger.ONE);
+    final static int SIZE = 48;
+
+    private BigInteger i;
+
+    Fp(byte[] b) {
+      this(new BigInteger(1, b));
+    }
+
+    Fp(long i) {
+      this(BigInteger.valueOf(i));
+    }
+
+    Fp(BigInteger i) {
+      this.i = i.mod(P);
+    }
+
+    Fp(String hex) {
+      this(new BigInteger(hex, 16));
+    }
+
+    Fp mul(Fp b) {
+      return new Fp(this.i.multiply(b.i));
+    }
+
+    Fp add(Fp b) {
+      return new Fp(this.i.add(b.i));
+    }
+
+    Fp sub(Fp b) {
+      return new Fp(this.i.subtract(b.i));
+    }
+
+    Fp neg() {
+      return new Fp(this.i.negate());
+    }
+
+    Fp square() {
+      return new Fp(this.i.pow(2));
+    }
+    
+    Fp inv() {
+      return new Fp(i.modInverse(P));   
+    } 
+
+    boolean isZero() {
+      return this.i.signum() == 0;
+    }
+
+    void serialize(byte[] out, int off) {
+      byte[] encoded = i.toByteArray();
+      int padding = SIZE - encoded.length;
+      System.arraycopy(encoded, 0, out, off + padding, encoded.length);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      if (o == this) {
+        return true;
+      }
+
+      if (!(o instanceof Fp)) {
+        return false;
+      }
+
+      Fp b = (Fp) o;
+      return b.i.equals(this.i); 
+    }
+  }
+
+  static class Fp2 {
+    final static Fp[] FROBENIUS_COEFFICIENTS = new Fp[] {
+      Fp.ONE,
+      new Fp("1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffaaaa")
+    };
+
+    final static Fp2 ZERO = new Fp2(Fp.ZERO, Fp.ZERO);
+    final static Fp2 ONE = new Fp2(Fp.ONE, Fp.ZERO);
+
+    final static int SIZE = Fp.SIZE * 2;
+
+    private Fp re;
+    private Fp im;
+
+    Fp2(Fp re, Fp im) {
+      this.re = re;
+      this.im = im;
+    }
+
+    Fp2(byte[] buf, int off) {
+      this(new Fp(Arrays.copyOfRange(buf, off + Fp.SIZE, off + Fp2.SIZE)), new Fp(Arrays.copyOfRange(buf, off, off + Fp.SIZE)));
+    }
+
+    int sgn0() {
+      boolean sign0 = this.re.i.testBit(0);
+      return sign0 || (this.re.isZero() && this.im.i.testBit(0)) ? 1 : 0;
+    }
+
+    Fp2 square() {
+      Fp a = this.re.add(this.im);
+      Fp b = this.re.sub(this.im);
+      Fp c = this.re.add(this.re);
+      return new Fp2(a.mul(b), c.mul(this.im));
+    }
+
+    Fp2 pow(long n) {
+      return this.pow(BigInteger.valueOf(n));
+    }
+
+    Fp2 pow(BigInteger n) {
+      if (n.signum() == 0) return Fp2.ONE;
+      if (n.equals(BigInteger.ONE)) return this;
+
+      Fp2 p = Fp2.ONE;
+      Fp2 d = this;
+
+      int bitLength = n.bitLength();
+      for (int i = 0; i < bitLength; i++) {
+        if (n.testBit(i)) {
+          p = p.mul(d);
+        }
+
+        d = d.square();
+      }
+
+      return p;      
+    }
+
+    boolean isZero() {
+      return this.re.isZero() && this.im.isZero();
+    }
+
+    Fp2 mul(Fp2 b) {
+      Fp t1 = this.re.mul(b.re);
+      Fp t2 = this.im.mul(b.im);
+      return new Fp2(t1.sub(t2), this.re.add(this.im).mul(b.re.add(b.im)).sub(t1.add(t2)));
+    }
+
+    Fp2 mul(long b) {
+      return mul(new Fp(b));
+    }
+
+    Fp2 mul(Fp b) {
+      return new Fp2(this.re.mul(b), this.im.mul(b));
+    }   
+
+    Fp2 add(Fp2 b) {
+      return new Fp2(this.re.add(b.re), this.im.add(b.im));
+    }
+
+    Fp2 sub(Fp2 b) {
+      return new Fp2(this.re.sub(b.re), this.im.sub(b.im));
+    }
+
+    Fp2 neg() {
+      return new Fp2(this.re.neg(), this.im.neg());
+    }  
+
+    Fp2 inv() {
+      Fp factor = this.re.square().add(this.im.square()).inv();
+      return new Fp2(factor.mul(this.re), factor.mul(this.im.neg()));
+    } 
+
+    Fp2 mulByNonresidue() {
+      return new Fp2(this.re.sub(this.im), this.re.add(this.im));
+    }
+
+    Fp2 frobeniusMap(int power) {
+      return new Fp2(this.re, this.im.mul(FROBENIUS_COEFFICIENTS[power % 2]));
+    }
+
+    void serialize(byte[] out, int off) {
+      this.im.serialize(out, off);
+      this.re.serialize(out, Fp.SIZE + off);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      if (o == this) {
+        return true;
+      }
+
+      if (!(o instanceof Fp2)) {
+        return false;
+      }
+
+      Fp2 b = (Fp2) o;
+      return b.re.equals(this.re) && b.im.equals(this.im); 
+    }
+  }
+
+  static class Fp6 {
+    final static Fp2[] FROBENIUS_COEFFICIENTS_1 = new Fp2[] {
+      Fp2.ONE,
+      new Fp2(
+        Fp.ZERO,
+        new Fp("1a0111ea397fe699ec02408663d4de85aa0d857d89759ad4897d29650fb85f9b409427eb4f49fffd8bfd00000000aaac")
+      ),
+      new Fp2(
+        new Fp("00000000000000005f19672fdf76ce51ba69c6076a0f77eaddb3a93be6f89688de17d813620a00022e01fffffffefffe"),
+        Fp.ZERO
+      ),
+      new Fp2(Fp.ZERO, Fp.ONE),
+      new Fp2(
+        new Fp("1a0111ea397fe699ec02408663d4de85aa0d857d89759ad4897d29650fb85f9b409427eb4f49fffd8bfd00000000aaac"),
+        Fp.ZERO
+      ),
+      new Fp2(
+        Fp.ZERO,
+        new Fp("00000000000000005f19672fdf76ce51ba69c6076a0f77eaddb3a93be6f89688de17d813620a00022e01fffffffefffe")
+      ),
+    };
+
+    final static Fp2[] FROBENIUS_COEFFICIENTS_2 = new Fp2[] {
+      Fp2.ONE,
+      new Fp2(
+        new Fp("1a0111ea397fe699ec02408663d4de85aa0d857d89759ad4897d29650fb85f9b409427eb4f49fffd8bfd00000000aaad"),
+        Fp.ZERO
+      ),
+      new Fp2(
+        new Fp("1a0111ea397fe699ec02408663d4de85aa0d857d89759ad4897d29650fb85f9b409427eb4f49fffd8bfd00000000aaac"),
+        Fp.ZERO
+      ),
+      new Fp2(
+        new Fp("1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffaaaa"),
+        Fp.ZERO
+      ),
+      new Fp2(
+        new Fp("00000000000000005f19672fdf76ce51ba69c6076a0f77eaddb3a93be6f89688de17d813620a00022e01fffffffefffe"),
+        Fp.ZERO
+      ),
+      new Fp2(
+        new Fp("00000000000000005f19672fdf76ce51ba69c6076a0f77eaddb3a93be6f89688de17d813620a00022e01fffffffeffff"),
+        Fp.ZERO
+      ),
+    };
+
+    final static Fp6 ZERO = new Fp6(Fp2.ZERO, Fp2.ZERO, Fp2.ZERO);
+    final static Fp6 ONE = new Fp6(Fp2.ONE, Fp2.ZERO, Fp2.ZERO);
+
+    private Fp2 c0;
+    private Fp2 c1;
+    private Fp2 c2;
+
+    Fp6(Fp2 c0, Fp2 c1, Fp2 c2) {
+      this.c0 = c0;
+      this.c1 = c1;
+      this.c2 = c2;
+    }
+
+    Fp6 add(Fp6 b) {
+      return new Fp6(this.c0.add(b.c0), this.c1.add(b.c1), this.c2.add(b.c2));
+    }
+
+    Fp6 sub(Fp6 b) {
+      return new Fp6(this.c0.sub(b.c0), this.c1.sub(b.c1), this.c2.sub(b.c2));
+    }
+  
+    Fp6 mul(Fp6 b) {
+      Fp2 t0 = this.c0.mul(b.c0);
+      Fp2 t1 = this.c1.mul(b.c1);
+      Fp2 t2 = this.c2.mul(b.c2);
+      
+      return new Fp6(
+        t0.add(this.c1.add(this.c2).mul(b.c1.add(b.c2)).sub(t1.add(t2)).mulByNonresidue()),
+        c0.add(c1).mul(b.c0.add(b.c1)).sub(t0.add(t1)).add(t2.mulByNonresidue()),
+        t1.add(c0.add(c2).mul(b.c0.add(b.c2)).sub(t0.add(t2)))
+      );
+    }
+
+    Fp6 mulByNonresidue() {
+      return new Fp6(this.c2.mulByNonresidue(), this.c0, this.c1);
+    } 
+    
+    Fp6 mulByFp2(Fp2 b) {
+      return new Fp6(this.c0.mul(b), this.c1.mul(b), this.c2.mul(b));
+    }
+  
+    Fp6 square() {
+      Fp2 t0 = this.c0.square();
+      Fp2 t1 = this.c0.mul(this.c1).mul(2);
+      Fp2 t3 = this.c1.mul(this.c2).mul(2);
+      Fp2 t4 = this.c2.square();
+
+      return new Fp6(
+        t3.mulByNonresidue().add(t0),
+        t4.mulByNonresidue().add(t1),
+        t1.add(this.c0.sub(this.c1).add(this.c2).square()).add(t3).sub(t0).sub(t4)
+      );
+    }
+
+    Fp6 neg() {
+      return new Fp6(this.c0.neg(), this.c1.neg(), this.c2.neg());
+    }  
+  
+    Fp6 inv() {
+      Fp2 t0 = this.c0.square().sub(this.c2.mul(this.c1).mulByNonresidue());
+      Fp2 t1 = this.c2.square().mulByNonresidue().sub(this.c0.mul(this.c1));
+      Fp2 t2 = this.c1.square().sub(this.c0.mul(this.c2));
+      Fp2 t4 = this.c2.mul(t1).add(this.c1.mul(t2)).mulByNonresidue().add(this.c0.mul(t0)).inv();
+      return new Fp6(t4.mul(t0), t4.mul(t1), t4.mul(t2));
+    }
+
+    Fp6 frobeniusMap(int power) {
+      return new Fp6(
+        this.c0.frobeniusMap(power),
+        this.c1.frobeniusMap(power).mul(FROBENIUS_COEFFICIENTS_1[power % 6]),
+        this.c2.frobeniusMap(power).mul(FROBENIUS_COEFFICIENTS_2[power % 6])
+      );
+    }  
+  }
+
+  static class Fp12 {
+    final static Fp2[] FROBENIUS_COEFFICIENTS = new Fp2[] {
+      Fp2.ONE,
+      new Fp2(
+        new Fp("1904d3bf02bb0667c231beb4202c0d1f0fd603fd3cbd5f4f7b2443d784bab9c4f67ea53d63e7813d8d0775ed92235fb8"),
+        new Fp("00fc3e2b36c4e03288e9e902231f9fb854a14787b6c7b36fec0c8ec971f63c5f282d5ac14d6c7ec22cf78a126ddc4af3")
+      ),
+      new Fp2(
+        new Fp("00000000000000005f19672fdf76ce51ba69c6076a0f77eaddb3a93be6f89688de17d813620a00022e01fffffffeffff"),
+        Fp.ZERO
+      ),
+      new Fp2(
+        new Fp("135203e60180a68ee2e9c448d77a2cd91c3dedd930b1cf60ef396489f61eb45e304466cf3e67fa0af1ee7b04121bdea2"),
+        new Fp("06af0e0437ff400b6831e36d6bd17ffe48395dabc2d3435e77f76e17009241c5ee67992f72ec05f4c81084fbede3cc09")
+      ),
+      new Fp2(
+        new Fp("00000000000000005f19672fdf76ce51ba69c6076a0f77eaddb3a93be6f89688de17d813620a00022e01fffffffefffe"),
+        Fp.ZERO
+      ),
+      new Fp2(
+        new Fp("144e4211384586c16bd3ad4afa99cc9170df3560e77982d0db45f3536814f0bd5871c1908bd478cd1ee605167ff82995"),
+        new Fp("05b2cfd9013a5fd8df47fa6b48b1e045f39816240c0b8fee8beadf4d8e9c0566c63a3e6e257f87329b18fae980078116")
+      ),
+      new Fp2(
+        new Fp("1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffaaaa"),
+        Fp.ZERO
+      ),
+      new Fp2(
+        new Fp("00fc3e2b36c4e03288e9e902231f9fb854a14787b6c7b36fec0c8ec971f63c5f282d5ac14d6c7ec22cf78a126ddc4af3"),
+        new Fp("1904d3bf02bb0667c231beb4202c0d1f0fd603fd3cbd5f4f7b2443d784bab9c4f67ea53d63e7813d8d0775ed92235fb8")
+      ),
+      new Fp2(
+        new Fp("1a0111ea397fe699ec02408663d4de85aa0d857d89759ad4897d29650fb85f9b409427eb4f49fffd8bfd00000000aaac"),
+        Fp.ZERO
+      ),
+      new Fp2(
+        new Fp("06af0e0437ff400b6831e36d6bd17ffe48395dabc2d3435e77f76e17009241c5ee67992f72ec05f4c81084fbede3cc09"),
+        new Fp("135203e60180a68ee2e9c448d77a2cd91c3dedd930b1cf60ef396489f61eb45e304466cf3e67fa0af1ee7b04121bdea2")
+      ),
+      new Fp2(
+        new Fp("1a0111ea397fe699ec02408663d4de85aa0d857d89759ad4897d29650fb85f9b409427eb4f49fffd8bfd00000000aaad"),
+        Fp.ZERO
+      ),
+      new Fp2(
+        new Fp("05b2cfd9013a5fd8df47fa6b48b1e045f39816240c0b8fee8beadf4d8e9c0566c63a3e6e257f87329b18fae980078116"),
+        new Fp("144e4211384586c16bd3ad4afa99cc9170df3560e77982d0db45f3536814f0bd5871c1908bd478cd1ee605167ff82995")
+      ),
+    };
+
+    final static Fp12 ZERO = new Fp12(Fp6.ZERO, Fp6.ZERO);
+    final static Fp12 ONE = new Fp12(Fp6.ONE, Fp6.ZERO);
+
+    private Fp6 c0;
+    private Fp6 c1;
+
+    Fp12(Fp6 c0, Fp6 c1) {
+      this.c0 = c0;
+      this.c1 = c1;
+    }
+
+    Fp12 add(Fp12 b) {
+      return new Fp12(this.c0.add(b.c0), this.c1.add(b.c1));
+    }
+
+    Fp12 sub(Fp12 b) {
+      return new Fp12(this.c0.sub(b.c0), this.c1.sub(b.c1));
+    }
+  
+    Fp12 mul(Fp12 b) {
+      Fp6 t1 = this.c0.mul(b.c0);
+      Fp6 t2 = this.c1.mul(b.c1);
+
+      return new Fp12(
+        t1.add(t2.mulByNonresidue()),
+        this.c0.add(this.c1).mul(b.c0.add(b.c1)).sub(t1.add(t2))
+      );
+    }
+  
+    Fp12 mulByFp2(Fp2 b) {
+      return new Fp12(this.c0.mulByFp2(b), this.c1.mulByFp2(b));
+    }
+  
+    Fp12 square() {
+      Fp6 ab = this.c0.mul(this.c1);
+
+      return new Fp12(
+        this.c1.mulByNonresidue().add(this.c0).mul(this.c0.add(this.c1)).sub(ab).sub(ab.mulByNonresidue()),
+        ab.add(ab)
+      );
+    }
+  
+    Fp12 inv() {
+      Fp6 t = this.c0.square().sub(this.c1.square().mulByNonresidue()).inv();
+      return new Fp12(this.c0.mul(t), this.c1.mul(t).neg());
+    }
+  
+    Fp12 frobeniusMap(int power) {
+      Fp6 r0 = this.c0.frobeniusMap(power);
+      Fp6 r1 = this.c1.frobeniusMap(power);
+      Fp2 coeff = FROBENIUS_COEFFICIENTS[power % 12];
+      return new Fp12(
+        r0,
+        new Fp6(r1.c0.mul(coeff), r1.c1.mul(coeff), r1.c2.mul(coeff))
+      );
+    }
+  }
+
+  static class SqrtDivFp2Res {
+    private boolean success;
+    private Fp2 value;
+
+    SqrtDivFp2Res(boolean success, Fp2 value) {
+      this.success = success;
+      this.value = value;
+    }
+  }
+
+  static class PointG2 {
+    final static Fp6 UT_ROOT = new Fp6(Fp2.ZERO, Fp2.ONE, Fp2.ZERO);
+    final static Fp12 WSQ = new Fp12(UT_ROOT, Fp6.ZERO);
+    final static Fp12 WCU = new Fp12(Fp6.ZERO, UT_ROOT);
+    final static Fp12 WSQ_INV = WSQ.inv();
+    final static Fp12 WCU_INV = WCU.inv();
+
+    final static PointG2 ZERO = new PointG2(Fp2.ONE, Fp2.ONE, Fp2.ZERO);
+
+    private Fp2 x;
+    private Fp2 y;
+    private Fp2 z;
+
+    PointG2(Fp2 x, Fp2 y, Fp2 z) {
+      this.x = x;
+      this.y = y;
+      this.z = z;
+    }
+
+    PointG2(byte[] buf) {
+      this.x = new Fp2(buf, 0);
+      this.y = new Fp2(buf, Fp2.SIZE);
+      this.z = Fp2.ONE;
+    }
+
+    PointG2 add(PointG2 b) {
+      if (this.isZero()) {
+        return b;
+      } else if (b.isZero()) {
+        return this;
+      }
+
+      Fp2 x1 = this.x;
+      Fp2 y1 = this.y;
+      Fp2 z1 = this.z;
+      Fp2 x2 = b.x;
+      Fp2 y2 = b.y;
+      Fp2 z2 = b.z;
+      Fp2 u1 = y2.mul(z1);
+      Fp2 u2 = y1.mul(z2);
+      Fp2 v1 = x2.mul(z1);
+      Fp2 v2 = x1.mul(z2);
+      if (v1.equals(v2) && u1.equals(u2)) {
+        return this.doubleP();
+      }
+
+      if (v1.equals(v2)) {
+        return PointG2.ZERO;
+      }
+
+      Fp2 u = u1.sub(u2);
+      Fp2 v = v1.sub(v2);
+      Fp2 vv = v.square();
+      Fp2 vvv = vv.mul(v);
+      Fp2 v2vv = v2.mul(vv);
+      Fp2 w = z1.mul(z2);
+      Fp2 a = u.square().mul(w).sub(vvv).sub(v2vv.add(v2vv));
+      Fp2 x3 = v.mul(a);
+      Fp2 y3 = u.mul(v2vv.sub(a)).sub(vvv.mul(u2));
+      Fp2 z3 = vvv.mul(w);
+      return new PointG2(x3, y3, z3);
+    }
+
+    private PointG2 doubleP() {
+      Fp2 w = this.x.square().mul(3);
+      Fp2 s = this.y.mul(this.z);
+      Fp2 ss = s.square();
+      Fp2 sss = ss.mul(s);
+      Fp2 b = this.x.mul(this.y).mul(s);
+      Fp2 h = w.square().sub(b.mul(8));
+      Fp2 x3 = h.mul(s).mul(2);
+      Fp2 y3 = w.mul(b.mul(4).sub(h)).sub(
+        this.y.square().mul(8).mul(ss)
+      );
+      Fp2 z3 = sss.mul(8);
+      return new PointG2(x3, y3, z3);
+    }
+
+    private boolean isZero() {
+      return this.z.isZero();
+    }
+
+    PointG2 clearCofactor() {
+      PointG2 t1 = this.mulCurveX();
+      PointG2 t2 = this.psi();
+      PointG2 t3 = this.doubleP();
+      t3 = t3.psi2();
+      t3 = t3.sub(t2);
+      t2 = t1.add(t2);
+      t2 = t2.mulCurveX();
+      t3 = t3.add(t2);
+      t3 = t3.sub(t1);
+      PointG2 q = t3.sub(this);
+      return q;
+    }
+
+    private PointG2 sub(PointG2 p) {
+      return this.add(p.neg());
+    }
+
+    private PointG2 neg() {
+      return new PointG2(x, y.neg(), z);
+    }
+
+    private PointG2 psi2() {
+      PointG2 p = toAffine();
+      return new PointG2(p.x.mul(PSI2_C1), p.y.neg(), p.z);
+    }
+
+    private PointG2 psi() {
+      PointG2 p = toAffine();
+      Fp2 x2 = WSQ_INV.mulByFp2(p.x).frobeniusMap(1).mul(WSQ).c0.c0;
+      Fp2 y2 = WCU_INV.mulByFp2(p.y).frobeniusMap(1).mul(WCU).c0.c0;
+      return new PointG2(x2, y2, p.z);
+    }
+
+    private PointG2 mulCurveX() {
+      return this.mulUnsafe(CURVE_X).neg();
+    }
+
+    private PointG2 mulUnsafe(BigInteger n) {
+      PointG2 point = PointG2.ZERO;
+      PointG2 d = this;
+
+      int bitLength = n.bitLength();
+      for (int i = 0; i < bitLength; i++) {
+        if (n.testBit(i)) {
+          point = point.add(d);
+        }
+
+        d = d.doubleP();
+      }
+
+      return point;
+    }
+
+    PointG2 toAffine() {
+      Fp2 invZ = this.z.inv();
+      return new PointG2(this.x.mul(invZ), this.y.mul(invZ), Fp2.ONE);
+    }
+
+    byte[] toByteArray(boolean compressed) {
+      PointG2 p = this.toAffine();
+      byte[] result = new byte[Fp2.SIZE * (compressed ? 1 : 2)];
+      p.x.serialize(result, 0);
+
+      if (compressed) {
+        result[0] |= (byte) 0x80;
+        BigInteger tmp = p.y.im.isZero() ? p.y.re.i.shiftLeft(1) : p.y.im.i.shiftLeft(1);
+        if (tmp.compareTo(P) > 0) {
+          result[0] |= 0x20;
+        }
+      } else {
+        p.y.serialize(result, Fp2.SIZE);
+      }
+
+      return result;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      if (o == this) {
+        return true;
+      }
+
+      if (!(o instanceof PointG2)) {
+        return false;
+      }
+
+      PointG2 p = (PointG2) o;
+      return p.x.equals(this.x) && p.y.equals(this.y) && p.z.equals(this.z); 
+    }
+  }
+}

lib/src/main/java/im/status/keycard/applet/CardDuplicator.java

@@ -1,141 +0,0 @@
-package im.status.keycard.applet;
-
-import im.status.keycard.io.APDUException;
-import im.status.keycard.io.CardChannel;
-import im.status.keycard.io.WrongPINException;
-
-import java.io.IOException;
-import java.security.SecureRandom;
-import java.util.HashSet;
-
-/**
- * Class helping with the card duplication process. Depending on the client's role, only some of the methods are relevant.
- */
-public class CardDuplicator {
-  private byte[] secret;
-  private KeycardCommandSet cmdSet;
-  private DuplicatorCallback cb;
-
-  private HashSet<byte[]> startedDuplication;
-  private HashSet<byte[]> addedEntropy;
-  private HashSet<byte[]> finishedDuplication;
-
-  /**
-   * Creates a CardDuplicator object. Regardless of the role of the client, this object must be kept and used for the
-   * entire duplication session. It cannot be reused for multiple sessions.
-   * 
-   * @param cmdSet the CommandSet to use
-   * @param cb the callback object for backups. This is needed only on the client performing steps requiring pairing
-   *           and authentication. Clients which only add entropy should pass null
-   */
-  public CardDuplicator(KeycardCommandSet cmdSet, DuplicatorCallback cb) {
-    this.cmdSet = cmdSet;
-    this.cb = cb;
-    this.startedDuplication = new HashSet<>();
-    this.addedEntropy = new HashSet<>();
-    this.finishedDuplication = new HashSet<>();
-
-    this.secret = new byte[32];
-    SecureRandom random = new SecureRandom();
-    random.nextBytes(this.secret);
-  }
-
-  /**
-   * Creates a CardDuplicator object. Only suitable for clients performing the role of adding entropy.
-   *
-   * @param channel the APDU channel
-   */
-  public CardDuplicator(CardChannel channel) {
-    this(new KeycardCommandSet(channel), null);
-  }
-
-  private ApplicationInfo selectAndCheck(HashSet<byte[]> processed) throws APDUException, IOException {
-    ApplicationInfo appInfo = new ApplicationInfo(cmdSet.select().checkOK().getData());
-
-    if (!processed.add(appInfo.getInstanceUID())) {
-      throw new IllegalStateException("The requested action has been already performed on this card");
-    }
-
-    return appInfo;
-  }
-
-  private void preamble(HashSet<byte[]> processed) throws IOException, APDUException {
-    ApplicationInfo appInfo = selectAndCheck(processed);
-
-    Pairing pairing = cb.getPairing(appInfo);
-
-    if (pairing == null) {
-      throw new APDUException("The given card is not paired");
-    }
-
-    cmdSet.setPairing(pairing);
-    cmdSet.autoOpenSecureChannel();
-    ApplicationStatus appStatus = new ApplicationStatus(cmdSet.getStatus(KeycardCommandSet.GET_STATUS_P1_APPLICATION).checkOK().getData());
-    int remainingAttempts = appStatus.getPINRetryCount();
-
-    while(remainingAttempts > 0) {
-      try {
-        cmdSet.verifyPIN(cb.getPIN(appInfo, remainingAttempts)).checkAuthOK();
-        break;
-      } catch(WrongPINException e) {
-        remainingAttempts = e.getRetryAttempts();
-      }
-    }
-
-    if (remainingAttempts <= 0) {
-      throw new APDUException("Card blocked");
-    }
-  }
-
-  /**
-   * Starts duplication session. Must be used on all cards taking part of in the duplication process.
-   *
-   * @param clientCount the number of clients which will be adding entropy for the key, including this one
-   *
-   * @throws IOException communication error
-   * @throws APDUException unexpected card response
-   * @throws IllegalStateException this card has already been used
-   */
-  public void startDuplication(int clientCount) throws IOException, APDUException, IllegalStateException {
-    preamble(startedDuplication);
-    cmdSet.duplicateKeyStart(clientCount, secret).checkOK();
-  }
-
-  /**
-   * Exports key. Must be used on the card designated as the source for the duplication.
-   *
-   * @throws IOException communication error
-   * @throws APDUException unexpected card response
-   */
-  public byte[] exportKey() throws IOException, APDUException, IllegalStateException {
-    preamble(finishedDuplication);
-    return cmdSet.duplicateKeyExport().checkOK().getData();
-  }
-
-  /**
-   * Imports key. Must be used on all cards designated as the target for the duplication.
-   *
-   * @param key the key to import
-   * @return the key UID
-   * @throws IOException communication error
-   * @throws APDUException unexpected card response
-   * @throws IllegalStateException this card has already been used
-   */
-  public byte[] importKey(byte[] key) throws IOException, APDUException, IllegalStateException {
-    preamble(finishedDuplication);
-    return cmdSet.duplicateKeyImport(key).checkOK().getData();
-  }
-
-  /**
-   * Adds entropy. Must be used on all cards taking part in the backup process. Each client taking part must use this
-   * exactly once, except for the client which started the backup.
-   *
-   * @throws IOException communication error
-   * @throws APDUException unexpected card response
-   * @throws IllegalStateException this card has already been used
-   */
-  public void addEntropy() throws IOException, APDUException, IllegalStateException {
-    selectAndCheck(addedEntropy);
-    cmdSet.duplicateKeyAddEntropy(secret).checkOK();
-  }
-}

lib/src/main/java/im/status/keycard/applet/CashApplicationInfo.java

@@ -0,0 +1,62 @@
+package im.status.keycard.applet;
+
+/**
+ * Parses the response from a SELECT command sent to the Cash applet.
+ */
+public class CashApplicationInfo {
+  public static final byte TLV_PUB_DATA = (byte) 0x82;
+
+  private byte[] pubKey;
+  private short appVersion;
+  private byte[] pubData;
+
+  /**
+   * Constructs an object by parsing the TLV data.
+   *
+   * @param tlvData the raw response data from the card
+   * @throws IllegalArgumentException the TLV does not follow the allowed format
+   */
+  public CashApplicationInfo(byte[] tlvData) throws IllegalArgumentException {
+    TinyBERTLV tlv = new TinyBERTLV(tlvData);
+
+    tlv.enterConstructed(ApplicationInfo.TLV_APPLICATION_INFO_TEMPLATE);
+    pubKey = tlv.readPrimitive(ApplicationInfo.TLV_PUB_KEY);
+    appVersion = (short) tlv.readInt();
+    pubData = tlv.readPrimitive(TLV_PUB_DATA);
+  }
+
+  /**
+   * The public key of the wallet.
+   *
+   * @return the public key
+   */
+  public byte[] getPubKey() {
+    return pubKey;
+  }
+
+  /**
+   * The application version, encoded as a short. The msb is the major revision number and the lsb is the minor one.
+   *
+   * @return the application version
+   */
+  public short getAppVersion() {
+    return appVersion;
+  }
+
+  /**
+   * A formatted application version.
+   * @return the string representation of the application version
+   */
+  public String getAppVersionString() {
+    return ApplicationInfo.getAppVersionString(appVersion);
+  }
+
+  /**
+   * The public data of the cash applet.
+   *
+   * @return the public key
+   */
+  public byte[] getPubData() {
+    return pubData;
+  }
+}

lib/src/main/java/im/status/keycard/applet/CashCommandSet.java

@@ -0,0 +1,68 @@
+package im.status.keycard.applet;
+
+import im.status.keycard.io.APDUCommand;
+import im.status.keycard.io.APDUResponse;
+import im.status.keycard.io.CardChannel;
+
+import java.io.IOException;
+
+/**
+ * Command set for the Cash applet.
+ */
+public class CashCommandSet {
+  private final CardChannel apduChannel;
+
+  /**
+   * Creates a CashCommandSet using the given APDU Channel
+   * @param apduChannel APDU channel
+   */
+  public CashCommandSet(CardChannel apduChannel) {
+    this.apduChannel = apduChannel;
+  }
+
+  /**
+   * Selects a Cash instance. The applet is assumed to have been installed with its default AID. The returned data is
+   * a public key which must be used to initialize the secure channel.
+   *
+   * @return the raw card response
+   * @throws IOException communication error
+   */
+  public APDUResponse select() throws IOException {
+    APDUCommand selectApplet = new APDUCommand(0x00, 0xA4, 4, 0, Identifiers.CASH_INSTANCE_AID);
+    return apduChannel.send(selectApplet);
+  }
+
+  /**
+   * Sends a SIGN APDU.
+   *
+   * @param data the data to sign
+   * @return the raw card response
+   * @throws IOException communication error
+   */
+  public APDUResponse sign(byte[] data, byte p2) throws IOException {
+    APDUCommand sign = new APDUCommand(0x80, KeycardCommandSet.INS_SIGN, 0x00, p2, data);
+    return apduChannel.send(sign);
+  }
+
+  /**
+   * Sends a SIGN APDU. This signs a precomputed hash with ECDSA so the input must be exactly 32-bytes long.
+   *
+   * @param data the data to sign
+   * @return the raw card response
+   * @throws IOException communication error
+   */
+  public APDUResponse sign(byte[] data) throws IOException {
+    return sign(data, KeycardCommandSet.SIGN_P2_ECDSA);
+  }
+
+  /**
+   * Sends a SIGN APDU. The message can be any length, and it is mapped to a point on G2 internally.
+   *
+   * @param data the data to sign
+   * @return the raw card response
+   * @throws IOException communication error
+   */
+  public APDUResponse signBLS(byte[] data) throws IOException {
+    return sign(BLS.hash(data), KeycardCommandSet.SIGN_P2_BLS12_381);
+  }
+}

lib/src/main/java/im/status/keycard/applet/DuplicatorCallback.java

@@ -1,24 +0,0 @@
-package im.status.keycard.applet;
-
-/**
- * Callback interface for duplication procedure.
- */
-public interface DuplicatorCallback {
-  /**
-   * Must return the pairing for the current card, represented by the applicationInfo parameter. If no pairing
-   * could be found, null must be returned.
-   *
-   * @param applicationInfo the application info template of the currently inserted card
-   * @return the pairing info or null
-   */
-  Pairing getPairing(ApplicationInfo applicationInfo);
-
-  /**
-   * Must return the PIN for the current card. This method can prompt the user or return a cached value.
-   *
-   * @param applicationInfo the application info template of the currently inserted card
-   * @param remainingAttempts the number of remaining PIN attempts
-   * @return the PIN
-   */
-  String getPIN(ApplicationInfo applicationInfo, int remainingAttempts);
-}

lib/src/main/java/im/status/keycard/applet/Ethereum.java

@@ -0,0 +1,19 @@
+package im.status.keycard.applet;
+
+import org.bouncycastle.crypto.digests.KeccakDigest;
+
+import java.util.Arrays;
+
+public class Ethereum {
+  private Ethereum() {
+
+  }
+
+  public static byte[] toEthereumAddress(byte[] publicKey) {
+    KeccakDigest digest = new KeccakDigest(256);
+    digest.update(publicKey, 1, (publicKey.length - 1));
+    byte[] hash = new byte[32];
+    digest.doFinal(hash, 0);
+    return Arrays.copyOfRange(hash,12, hash.length);
+  }
+}

lib/src/main/java/im/status/keycard/applet/Identifiers.java

@@ -13,6 +13,9 @@ public class Identifiers {
   public static final byte[] NDEF_AID = Hex.decode("A000000804000102");
   public static final byte[] NDEF_INSTANCE_AID = Hex.decode("D2760000850101");
 
+  public static final byte[] CASH_AID = Hex.decode("A000000804000103");
+  public static final byte[] CASH_INSTANCE_AID = Hex.decode("A00000080400010301");
+
   /**
    * Gets the instance AID of the default instance of the Keycard applet.
    *

lib/src/main/java/im/status/keycard/applet/KeycardCommandSet.java

@@ -28,10 +28,11 @@ public class KeycardCommandSet {
   static final byte INS_GENERATE_MNEMONIC = (byte) 0xD2;
   static final byte INS_REMOVE_KEY = (byte) 0xD3;
   static final byte INS_GENERATE_KEY = (byte) 0xD4;
-  static final byte INS_DUPLICATE_KEY = (byte) 0xD5;
   static final byte INS_SIGN = (byte) 0xC0;
   static final byte INS_SET_PINLESS_PATH = (byte) 0xC1;
   static final byte INS_EXPORT_KEY = (byte) 0xC2;
+  static final byte INS_GET_DATA = (byte) 0xCA;
+  static final byte INS_STORE_DATA = (byte) 0xE2;
 
   public static final byte CHANGE_PIN_P1_USER_PIN = 0x00;
   public static final byte CHANGE_PIN_P1_PUK = 0x01;
@@ -53,6 +54,18 @@ public class KeycardCommandSet {
   static final byte DUPLICATE_KEY_P1_EXPORT = 0x02;
   static final byte DUPLICATE_KEY_P1_IMPORT = 0x03;
 
+  static final byte SIGN_P1_CURRENT_KEY = 0x00;
+  static final byte SIGN_P1_DERIVE = 0x01;
+  static final byte SIGN_P1_DERIVE_AND_MAKE_CURRENT = 0x02;
+  static final byte SIGN_P1_PINLESS = 0x03;
+
+  public static final byte SIGN_P2_ECDSA = 0x00;
+  public static final byte SIGN_P2_BLS12_381 = 0x01;
+
+  public static final byte STORE_DATA_P1_PUBLIC = 0x00;
+  public static final byte STORE_DATA_P1_NDEF = 0x01;
+  public static final byte STORE_DATA_P1_CASH = 0x02;
+
   public static final int GENERATE_MNEMONIC_12_WORDS = 0x04;
   public static final int GENERATE_MNEMONIC_15_WORDS = 0x05;
   public static final int GENERATE_MNEMONIC_18_WORDS = 0x06;
@@ -154,8 +167,9 @@ public class KeycardCommandSet {
    * Opens the secure channel. Calls the corresponding method of the SecureChannel class.
    *
    * @throws IOException communication error
+   * @throws APDUException secure channel error
    */
-  public void autoOpenSecureChannel() throws IOException {
+  public void autoOpenSecureChannel() throws IOException, APDUException {
     secureChannel.autoOpenSecureChannel(apduChannel);
   }
 
@@ -163,8 +177,9 @@ public class KeycardCommandSet {
    * Automatically pairs. Derives the secret from the given password.
    *
    * @throws IOException communication error
+   * @throws APDUException pairing error
    */
-  public void autoPair(String pairingPassword) throws IOException {
+  public void autoPair(String pairingPassword) throws IOException, APDUException {
     byte[] secret = pairingPasswordToSecret(pairingPassword);
 
     secureChannel.autoPair(apduChannel, secret);
@@ -193,8 +208,9 @@ public class KeycardCommandSet {
    * Automatically pairs. Calls the corresponding method of the SecureChannel class.
    *
    * @throws IOException communication error
+   * @throws APDUException pairing error
    */
-  public void autoPair(byte[] sharedSecret) throws IOException {
+  public void autoPair(byte[] sharedSecret) throws IOException, APDUException {
     secureChannel.autoPair(apduChannel, sharedSecret);
   }
 
@@ -202,8 +218,9 @@ public class KeycardCommandSet {
    * Automatically unpairs. Calls the corresponding method of the SecureChannel class.
    *
    * @throws IOException communication error
+   * @throws APDUException unpairing error
    */
-  public void autoUnpair() throws IOException {
+  public void autoUnpair() throws IOException, APDUException {
     secureChannel.autoUnpair(apduChannel);
   }
 
@@ -244,6 +261,9 @@ public class KeycardCommandSet {
 
   /**
    * Unpair all other clients.
+   *
+   * @throws IOException communication error
+   * @throws APDUException unpairing error
    */
   public void unpairOthers() throws IOException, APDUException {
     secureChannel.unpairOthers(apduChannel);
@@ -262,19 +282,7 @@ public class KeycardCommandSet {
     return secureChannel.transmit(apduChannel, getStatus);
   }
 
-  /**
-   * Sends a SET NDEF APDU.
-   *
-   * @param ndef the data field of the APDU
-   * @return the raw card response
-   * @throws IOException communication error
-   */
-  public APDUResponse setNDEF(byte[] ndef) throws IOException {
-    APDUCommand setNDEF = secureChannel.protectedCommand(0x80, INS_SET_NDEF, 0, 0, ndef);
-    return secureChannel.transmit(apduChannel, setNDEF);
-  }
-
-  /**
+   /**
    * Sends a VERIFY PIN APDU. The raw bytes of the given string are encrypted using the secure channel and used as APDU
    * data.
    *
@@ -482,65 +490,57 @@ public class KeycardCommandSet {
   }
 
   /**
-   * Sends a DUPLICATE KEY APDU. The P1 is set to 00, P2 to the entropy count and the data is the first entropy piece.
-   * This starts a duplication session. Requires an open Secure Channel and authenticated PIN.
+   * Sends a SIGN APDU. This signs a precomputed hash that must be exactly 32-bytes long.
    *
-   * @param entropyCount the number of entropy pieces to expect, including the one in this APDU
-   * @param firstEntropy a random 32-byte number
+   * @param hash the hash to sign
    * @return the raw card response
    * @throws IOException communication error
    */
-  public APDUResponse duplicateKeyStart(int entropyCount, byte[] firstEntropy) throws IOException {
-    APDUCommand duplicateKeyStart = secureChannel.protectedCommand(0x80, INS_DUPLICATE_KEY, DUPLICATE_KEY_P1_START, entropyCount, firstEntropy);
-    return secureChannel.transmit(apduChannel, duplicateKeyStart);
+  public APDUResponse sign(byte[] hash) throws IOException {
+    return sign(hash, SIGN_P1_CURRENT_KEY);
   }
 
   /**
-   * Sends a DUPLICATE KEY APDU. The P1 is set to 01 and the data is the entropy. This adds entropy and does not require
-   * a Secure Channel or authenticated PIN.
+   * Sends a SIGN APDU. This signs a precomputed hash that must be exactly 32-bytes long. The key used to sign is given
+   * as a parameter.
    *
-   * @param entropy a random 32-byte number
+   * @param hash the hash to sign
+   * @params path the path of the key to use
+   * @param makeCurrent ture if the key used to sign should become the current key, false otherwise
    * @return the raw card response
    * @throws IOException communication error
    */
-  public APDUResponse duplicateKeyAddEntropy(byte[] entropy) throws IOException {
-    APDUCommand duplicateKeyAddEntropy = new APDUCommand(0x80, INS_DUPLICATE_KEY, DUPLICATE_KEY_P1_ADD_ENTROPY, 0, secureChannel.oneShotEncrypt(entropy));
-    return apduChannel.send(duplicateKeyAddEntropy);
+  public APDUResponse signWithPath(byte[] hash, String path, boolean makeCurrent) throws IOException {
+    KeyPath keyPath = new KeyPath(path);
+    byte[] pathData = keyPath.getData();
+    byte[] data = Arrays.copyOf(hash, hash.length + pathData.length);
+    System.arraycopy(pathData, 0, data, hash.length, pathData.length);
+    return sign(data, keyPath.getSource() | (makeCurrent ? SIGN_P1_DERIVE_AND_MAKE_CURRENT : SIGN_P1_DERIVE));
   }
 
   /**
-   * Sends a DUPLICATE KEY APDU. The P1 is set to 02. This exports the encrypted master key including chaining code.
+   * Sends a SIGN APDU. This signs a precomputed hash that must be exactly 32-bytes long. The pinless path will be used
+   * to sign. This command is the only variant of SIGN which can also be executed without a Secure Channel.
    *
+   * @param hash the hash to sign
    * @return the raw card response
    * @throws IOException communication error
    */
-  public APDUResponse duplicateKeyExport() throws IOException {
-    APDUCommand duplicateKeyExport = secureChannel.protectedCommand(0x80, INS_DUPLICATE_KEY, DUPLICATE_KEY_P1_EXPORT, 0, new byte[0]);
-    return secureChannel.transmit(apduChannel, duplicateKeyExport);
+  public APDUResponse signPinless(byte[] hash) throws IOException {
+    return sign(hash, SIGN_P1_PINLESS);
   }
 
   /**
-   * Sends a DUPLICATE KEY APDU. The P1 is set to 03. This imports an encrypted master key including chaining code. The
-   * response data contains the key UID of the imported key.
-   *
-   * @param key the key, exported from another card in the same duplication session.
-   * @return the raw card response
-   * @throws IOException communication error
-   */
-  public APDUResponse duplicateKeyImport(byte[] key) throws IOException {
-    APDUCommand duplicateKeyImport = secureChannel.protectedCommand(0x80, INS_DUPLICATE_KEY, DUPLICATE_KEY_P1_IMPORT, 0, key);
-    return secureChannel.transmit(apduChannel, duplicateKeyImport);
-  }
-
-  /**
-   * Sends a SIGN APDU. This signs a precomputed hash so the input must be exactly 32-bytes long.
+   * Sends a SIGN APDU. This signs a precomputed hash so the input must be exactly 32-bytes long, eventually followed by
+   * a derivation path.
    *
+   * @param p1 the p1 parameter
    * @param data the data to sign
    * @return the raw card response
    * @throws IOException communication error
    */
-  public APDUResponse sign(byte[] data) throws IOException {
-    APDUCommand sign = secureChannel.protectedCommand(0x80, INS_SIGN, 0x00, 0x00, data);
+  public APDUResponse sign(byte[] data, int p1) throws IOException {
+    APDUCommand sign = secureChannel.protectedCommand(0x80, INS_SIGN, p1, 0x00, data);
     return secureChannel.transmit(apduChannel, sign);
   }
 
@@ -581,6 +581,33 @@ public class KeycardCommandSet {
     return secureChannel.transmit(apduChannel, deriveKey);
   }
 
+  /**
+   * Sends a SET PINLESS PATH APDU. The path must be absolute, that is starting from the master key.
+
+   * @param path the path. Must be an absolute path (i.e: starting from the master key)
+   * @return the raw card response
+   * @throws IOException communication error
+   */
+  public APDUResponse setPinlessPath(String path) throws IOException {
+    KeyPath keyPath = new KeyPath(path);
+    if (keyPath.getSource() != DERIVE_P1_SOURCE_MASTER) {
+      throw new IllegalArgumentException("Only absolute paths can be set as PINLESS path");
+    }
+
+    return setPinlessPath(keyPath.getData());
+  }
+
+  /**
+   * Sends an empty SET PINLESS PATH APDU, resetting it. After this command the card does not have a PINless path until
+   * a new one is set.
+   *
+   * @return the raw card response
+   * @throws IOException communication error
+   */
+  public APDUResponse resetPinlessPath() throws IOException {
+      return setPinlessPath(new byte[]{});
+  }
+
   /**
    * Sends a SET PINLESS PATH APDU. The data is encrypted and sent as-is.
    *
@@ -588,7 +615,7 @@ public class KeycardCommandSet {
    * @return the raw card response
    * @throws IOException communication error
    */
-  public APDUResponse setPinlessPath(byte [] data) throws IOException {
+  public APDUResponse setPinlessPath(byte[] data) throws IOException {
     APDUCommand setPinlessPath = secureChannel.protectedCommand(0x80, INS_SET_PINLESS_PATH, 0x00, 0x00, data);
     return secureChannel.transmit(apduChannel, setPinlessPath);
   }
@@ -648,7 +675,56 @@ public class KeycardCommandSet {
   }
 
   /**
-   * Sends the INIT command to the card.
+   * Sends a GET DATA APDU.
+   *
+   * @param dataType the type of data to be stored
+   * @return the raw card response
+   * @throws IOException communication error
+   */
+  public APDUResponse getData(byte dataType) throws IOException {
+    APDUCommand getData = secureChannel.protectedCommand(0x80, INS_GET_DATA, dataType, 0, new byte[0]);
+    return secureChannel.transmit(apduChannel, getData);
+  }
+
+  /**
+   * Sends a STORE DATA APDU for NDEF.
+   *
+   * @param ndef the data field of the APDU
+   * @return the raw card response
+   * @throws IOException communication error
+   */
+  public APDUResponse setNDEF(byte[] ndef) throws IOException {
+    if ((info.getAppVersion() >> 8) > 2) {
+      if ((ndef.length - 2) != ((ndef[0] << 8) | ndef[1])) {
+        byte[] tmp = new byte[ndef.length + 2];
+        tmp[0] = (byte) (ndef.length >> 8);
+        tmp[1] = (byte) (ndef.length & 0xff);
+        System.arraycopy(ndef, 0, tmp, 2, ndef.length);
+        ndef = tmp;
+      }
+
+      return storeData(ndef, STORE_DATA_P1_NDEF);
+    } else {
+      APDUCommand setNDEF = secureChannel.protectedCommand(0x80, INS_SET_NDEF, 0, 0, ndef);
+      return secureChannel.transmit(apduChannel, setNDEF);
+    }
+  }
+
+   /**
+   * Sends a STORE DATA APDU.
+   *
+   * @param data the data field of the APDU
+   * @param dataType the type of data to be stored
+   * @return the raw card response
+   * @throws IOException communication error
+   */
+  public APDUResponse storeData(byte[] data, byte dataType) throws IOException {
+    APDUCommand storeData = secureChannel.protectedCommand(0x80, INS_STORE_DATA, dataType, 0, data);
+    return secureChannel.transmit(apduChannel, storeData);
+  }
+
+  /**
+   * Sends the INIT command to the card. If either pinRetries or pukRetries is zero, neither will be sent.
    *
    * @param pin the PIN
    * @param puk the PUK
@@ -657,7 +733,22 @@ public class KeycardCommandSet {
    * @throws IOException communication error
    */
   public APDUResponse init(String pin, String puk, String pairingPassword) throws IOException {
-    return this.init(pin, puk, pairingPasswordToSecret(pairingPassword));
+    return this.init(pin, puk, pairingPassword, (byte) 0, (byte) 0);
+  }
+
+  /**
+   * Sends the INIT command to the card.
+   *
+   * @param pin the PIN
+   * @param puk the PUK
+   * @param pairingPassword pairing password
+   * @param pinRetries the number of allowed PIN retries
+   * @param pukRetries the number of allowed PUK retries
+   * @return the raw card response
+   * @throws IOException communication error
+   */
+  public APDUResponse init(String pin, String puk, String pairingPassword, byte pinRetries, byte pukRetries) throws IOException {
+    return this.init(pin, puk, pairingPasswordToSecret(pairingPassword), pinRetries, pukRetries);
   }
 
   /**
@@ -670,9 +761,31 @@ public class KeycardCommandSet {
    * @throws IOException communication error
    */
   public APDUResponse init(String pin, String puk, byte[] sharedSecret) throws IOException {
-    byte[] initData = Arrays.copyOf(pin.getBytes(), pin.length() + puk.length() + sharedSecret.length);
+    return init(pin, puk, sharedSecret, (byte) 0, (byte) 0);
+  }
+
+  /**
+   * Sends the INIT command to the card. If either pinRetries or pukRetries is zero, neither will be sent.
+   *
+   * @param pin the PIN
+   * @param puk the PUK
+   * @param sharedSecret the shared secret for pairing
+   * @param pinRetries the number of allowed PIN retries
+   * @param pukRetries the number of allowed PUK retries
+   * @return the raw card response
+   * @throws IOException communication error
+   */
+  public APDUResponse init(String pin, String puk, byte[] sharedSecret, byte pinRetries, byte pukRetries) throws IOException {
+    boolean addRetries = !((pinRetries == 0) || (pukRetries == 0));
+    byte[] initData = Arrays.copyOf(pin.getBytes(), pin.length() + puk.length() + sharedSecret.length + (addRetries ? 2 : 0));
     System.arraycopy(puk.getBytes(), 0, initData, pin.length(), puk.length());
     System.arraycopy(sharedSecret, 0, initData, pin.length() + puk.length(), sharedSecret.length);
+
+    if (addRetries) {
+      initData[initData.length - 2] = pinRetries;
+      initData[initData.length - 1] = pukRetries;
+    }
+
     APDUCommand init = new APDUCommand(0x80, INS_INIT, 0, 0, secureChannel.oneShotEncrypt(initData));
     return apduChannel.send(init);
   }

lib/src/main/java/im/status/keycard/applet/Metadata.java

@@ -0,0 +1,106 @@
+package im.status.keycard.applet;
+
+import java.io.ByteArrayOutputStream;
+import java.nio.charset.Charset;
+import java.util.SortedSet;
+import java.util.TreeSet;
+
+public class Metadata {
+  private String cardName;
+  private SortedSet<Long> wallets;
+  
+  public static Metadata fromData(byte[] data) {
+    int version = (data[0] & 0xe0) >> 5;
+
+    if (version != 1) {
+      throw new RuntimeException("Invalid version");
+    }
+
+    int namelen = (data[0] & 0x1f);
+    int off = 1;
+
+    String cardName = new String(data, off, namelen, Charset.forName("US-ASCII"));
+    off += namelen;
+
+    SortedSet<Long> set = new TreeSet<>();
+
+    while(off < data.length) {
+      int[] start = TinyBERTLV.readNum(data, off);
+      int[] count = TinyBERTLV.readNum(data, start[1]);
+      off = count[1];
+      long s = start[0] & 0xffffffffl;
+      buildRange(set, s, (s + count[0]));
+    }
+
+    return new Metadata(cardName, set);
+  }
+
+  private static void buildRange(SortedSet<Long> set, long start, long end) {
+    for (long i = start; i <= end; i++) {
+      set.add(i);
+    }
+  }
+
+  Metadata(String cardName, SortedSet<Long> wallets) {
+    this.cardName = cardName;
+    this.wallets = wallets;
+  }
+
+  public Metadata(String cardName) {
+    this(cardName, new TreeSet<>());
+  }
+
+  public String getCardName() {
+    return cardName;
+  }
+
+  public void setCardName(String cardName) {
+    if (cardName.length() > 20) {
+      throw new IllegalArgumentException("card name too long");
+    }
+    
+    this.cardName = cardName;
+  }
+
+  public SortedSet<Long> getWallets() {
+    return wallets;
+  }
+
+  public void addWallet(long w) {
+    this.wallets.add(w);
+  }
+
+  public void removeWallet(long w) {
+    this.wallets.remove(w);
+  }
+
+  public byte[] toByteArray() {
+    ByteArrayOutputStream os = new ByteArrayOutputStream();
+    byte[] name = this.cardName.getBytes(Charset.forName("US-ASCII"));
+    os.write(0x20 | name.length);
+    os.write(name, 0, name.length);
+
+    if (wallets.isEmpty()) {
+      return os.toByteArray();
+    }
+
+    long start = wallets.first();
+    int len = 0;
+
+    for (Long w : wallets.tailSet(start + 1)) {
+      if (w == (start + len + 1)) {
+        len++;
+      } else {
+        TinyBERTLV.writeNum(os, (int) start);
+        TinyBERTLV.writeNum(os, len);
+        len = 0;
+        start = w;
+      }
+    }
+
+    TinyBERTLV.writeNum(os, (int) start);
+    TinyBERTLV.writeNum(os, len);
+
+    return os.toByteArray();
+  }
+}

lib/src/main/java/im/status/keycard/applet/Mnemonic.java

@@ -3,10 +3,6 @@ package im.status.keycard.applet;
 import javax.crypto.SecretKey;
 import javax.crypto.SecretKeyFactory;
 import javax.crypto.spec.PBEKeySpec;
-import java.io.IOException;
-import java.net.URL;
-import java.util.ArrayList;
-import java.util.Scanner;
 
 public class Mnemonic {
   private final static int WORDLIST_SIZE = 2048;
@@ -41,28 +37,11 @@ public class Mnemonic {
   }
 
   /**
-   * Retrieves the official BIP39 english wordlist from GitHub.
+   * Returns the official BIP39 english wordlist as fetched from https://raw.githubusercontent.com/bitcoin/bips/master/bip-0039/english.txt on 23 Oct 2019.
    *
-   * @throws IOException network error
    */
-  public void fetchBIP39EnglishWordlist() throws IOException {
-    URL remoteList = new URL("https://raw.githubusercontent.com/bitcoin/bips/master/bip-0039/english.txt");
-    Scanner scanner = new Scanner(remoteList.openStream());
-
-    ArrayList<String> list = new ArrayList<>();
-
-    while(scanner.hasNextLine()) {
-      list.add(scanner.nextLine());
-    }
-
-    scanner.close();
-
-    if (list.size() != WORDLIST_SIZE) {
-      throw new IllegalArgumentException("The list must contain exactly 2048 entries");
-    }
-
-    this.wordlist = new String[WORDLIST_SIZE];
-    list.toArray(this.wordlist);
+  public void fetchBIP39EnglishWordlist() {
+    this.wordlist = MnemonicEnglishDictionary.words;
   }
 
   /**
@@ -145,7 +124,7 @@ public class Mnemonic {
       PBEKeySpec spec = new PBEKeySpec(mnemonicPhrase.toCharArray(), ("mnemonic" + password).getBytes(), 2048, 512);
       key = skf.generateSecret(spec);
     } catch (Exception e) {
-      throw new RuntimeException("Is Bouncycastle correctly initialized?");
+      throw new RuntimeException("Is Bouncycastle correctly initialized?", e);
     }
 
     return key.getEncoded();

lib/src/main/java/im/status/keycard/applet/RecoverableSignature.java

@@ -105,6 +105,15 @@ public class RecoverableSignature {
     return s;
   }
 
+  /**
+   * The Ethereum address of the signing key
+   *
+   * @return ethereum address of the signing key
+   */
+  public byte[] getEthereumAddress() {
+    return Ethereum.toEthereumAddress(publicKey);
+  }
+
   private static byte[] recoverFromSignature(int recId, BigInteger e, BigInteger r, BigInteger s) {
     BigInteger n = CURVE.getN();
     BigInteger i = BigInteger.valueOf((long) recId / 2);

lib/src/main/java/im/status/keycard/applet/SecureChannelSession.java

@@ -118,24 +118,14 @@ public class SecureChannelSession {
    * @param apduChannel the apdu channel
    * @throws IOException communication error
    */
-  public void autoOpenSecureChannel(CardChannel apduChannel) throws IOException {
+  public void autoOpenSecureChannel(CardChannel apduChannel) throws IOException, APDUException {
     APDUResponse response = openSecureChannel(apduChannel, pairing.getPairingIndex(), publicKey);
-
-    if (response.getSw() != 0x9000) {
-      throw new IOException("OPEN SECURE CHANNEL failed");
-    }
-
+    response.checkOK("OPEN SECURE CHANNEL failed");
     processOpenSecureChannelResponse(response);
 
     response = mutuallyAuthenticate(apduChannel);
-
-    if (response.getSw() != 0x9000) {
-      throw new IOException("MUTUALLY AUTHENTICATE failed");
-    }
-
-    if(!verifyMutuallyAuthenticateResponse(response)) {
-      throw new IOException("Invalid authentication data from the card");
-    }
+    response.checkOK("MUTUALLY AUTHENTICATE failed");
+    verifyMutuallyAuthenticateResponse(response);
   }
 
   /**
@@ -168,8 +158,10 @@ public class SecureChannelSession {
    * @param response the card response
    * @return true if response is correct, false otherwise
    */
-  public boolean verifyMutuallyAuthenticateResponse(APDUResponse response) {
-    return response.getData().length == SC_SECRET_LENGTH;
+  public void verifyMutuallyAuthenticateResponse(APDUResponse response) throws APDUException {
+    if (response.getData().length != SC_SECRET_LENGTH) {
+      throw new APDUException("Invalid authentication data from the card");
+    }
   }
 
   /**
@@ -178,14 +170,10 @@ public class SecureChannelSession {
    * @param apduChannel the apdu channel
    * @throws IOException communication error
    */
-  public void autoPair(CardChannel apduChannel, byte[] sharedSecret) throws IOException {
+  public void autoPair(CardChannel apduChannel, byte[] sharedSecret) throws IOException, APDUException {
     byte[] challenge = new byte[32];
     random.nextBytes(challenge);
-    APDUResponse resp = pair(apduChannel, PAIR_P1_FIRST_STEP, challenge);
-
-    if (resp.getSw() != 0x9000) {
-      throw new IOException("Pairing failed on step 1");
-    }
+    APDUResponse resp = pair(apduChannel, PAIR_P1_FIRST_STEP, challenge).checkOK("Pairing failed on step 1");
 
     byte[] respData = resp.getData();
     byte[] cardCryptogram = Arrays.copyOf(respData, 32);
@@ -204,18 +192,13 @@ public class SecureChannelSession {
     checkCryptogram = md.digest(challenge);
 
     if (!Arrays.equals(checkCryptogram, cardCryptogram)) {
-      throw new IOException("Invalid card cryptogram");
+      throw new APDUException("Invalid card cryptogram");
     }
 
     md.update(sharedSecret);
     checkCryptogram = md.digest(cardChallenge);
 
-    resp = pair(apduChannel, PAIR_P1_LAST_STEP, checkCryptogram);
-
-    if (resp.getSw() != 0x9000) {
-      throw new IOException("Pairing failed on step 2");
-    }
-
+    resp = pair(apduChannel, PAIR_P1_LAST_STEP, checkCryptogram).checkOK("Pairing failed on step 2");
     respData = resp.getData();
     md.update(sharedSecret);
     pairing = new Pairing(md.digest(Arrays.copyOfRange(respData, 1, respData.length)), respData[0]);
@@ -227,12 +210,8 @@ public class SecureChannelSession {
    * @param apduChannel the apdu channel
    * @throws IOException communication error
    */
-  public void autoUnpair(CardChannel apduChannel) throws IOException {
-    APDUResponse resp = unpair(apduChannel, pairing.getPairingIndex());
-
-    if (resp.getSw() != 0x9000) {
-      throw new IOException("Unpairing failed");
-    }
+  public void autoUnpair(CardChannel apduChannel) throws IOException, APDUException {
+    unpair(apduChannel, pairing.getPairingIndex()).checkOK("Unpairing failed");
   }
 
   /**

lib/src/main/java/im/status/keycard/applet/TinyBERTLV.java

@@ -1,5 +1,6 @@
 package im.status.keycard.applet;
 
+import java.io.ByteArrayOutputStream;
 import java.util.Arrays;
 
 /**
@@ -14,6 +15,57 @@ public class TinyBERTLV {
   private byte[] buffer;
   private int pos;
 
+  public static int[] readNum(byte[] buf, int off) {
+    int len = buf[off++] & 0xff;
+    int lenlen = 0;
+
+    if ((len & 0x80) == 0x80) {
+      lenlen = len & 0x7f;
+      len = readVal(buf, off, lenlen);
+    }
+
+    return new int[] {len, off + lenlen};
+  }
+
+  public static int readVal(byte[] val, int off, int len) {
+    switch (len) {
+      case 1:
+        return val[off] & 0xff;
+      case 2:
+        return ((val[off] & 0xff) << 8) | (val[off+1] & 0xff);
+      case 3:
+        return ((val[off] & 0xff) << 16) | ((val[off+1] & 0xff) << 8) | (val[off+2] & 0xff);
+      case 4:
+        return ((val[off] & 0xff) << 24) | ((val[off+1] & 0xff) << 16) | ((val[off+2] & 0xff) << 8) | (val[off+3] & 0xff);
+      default:
+        throw new IllegalArgumentException("Integers of length " + len + " are unsupported");
+    }    
+  }
+
+  public static void writeNum(ByteArrayOutputStream os, int len) {
+    if ((len & 0xff000000) != 0) {
+      os.write(0x84);
+      os.write((len & 0xff000000) >> 24);
+      os.write((len & 0x00ff0000) >> 16);
+      os.write((len & 0x0000ff00) >> 8);
+      os.write(len & 0x000000ff);
+    } else if ((len & 0x00ff0000) != 0) {
+      os.write(0x83);
+      os.write((len & 0x00ff0000) >> 16);
+      os.write((len & 0x0000ff00) >> 8);
+      os.write(len & 0x000000ff);
+    } else if ((len & 0x0000ff00) != 0) {
+      os.write(0x82);
+      os.write((len & 0x0000ff00) >> 8);
+      os.write(len & 0x000000ff);
+    } else if ((len & 0x00000080) != 0) {
+      os.write(0x81);
+      os.write(len & 0x000000ff);
+    } else {
+      os.write(len);
+    }
+  }
+
   public TinyBERTLV(byte[] buffer) {
     this.buffer = buffer;
     this.pos = 0;
@@ -64,19 +116,7 @@ public class TinyBERTLV {
    */
   public int readInt() throws IllegalArgumentException {
     byte[] val = readPrimitive(TLV_INT);
-
-    switch (val.length) {
-      case 1:
-        return val[0] & 0xff;
-      case 2:
-        return ((val[0] & 0xff) << 8) | (val[1] & 0xff);
-      case 3:
-        return ((val[0] & 0xff) << 16) | ((val[1] & 0xff) << 8) | (val[2] & 0xff);
-      case 4:
-        return ((val[0] & 0xff) << 24) | ((val[1] & 0xff) << 16) | ((val[2] & 0xff) << 8) | (val[3] & 0xff);
-      default:
-        throw new IllegalArgumentException("Integers of length " + val.length + " are unsupported");
-    }
+    return TinyBERTLV.readVal(val, 0, val.length);
   }
 
   /**
@@ -104,13 +144,9 @@ public class TinyBERTLV {
    * @return the tag
    */
   public int readLength() {
-    int len = buffer[pos++] & 0xff;
-
-    if (len == 0x81) {
-      len = buffer[pos++] & 0xff;
-    }
-
-    return len;
+    int[] len = TinyBERTLV.readNum(buffer, pos);
+    pos = len[1];
+    return len[0];
   }
 
   private void checkTag(int expected, int actual) throws IllegalArgumentException {

lib/src/main/java/im/status/keycard/globalplatform/Crypto.java

@@ -61,7 +61,7 @@ public class Crypto {
     } catch (InvalidKeyException | IllegalBlockSizeException | BadPaddingException | InvalidAlgorithmParameterException e) {
       throw new RuntimeException("error generating session keys.", e);
     } catch (NoSuchProviderException e) {
-      throw new RuntimeException("SpongyCastle not installed");
+      throw new RuntimeException("BouncyCastle not installed");
     }
   }
 
@@ -121,6 +121,21 @@ public class Crypto {
     }
   }
 
+  public static byte[] ecb3des(byte[] key, byte[] data) {
+    try {
+      Cipher cipher = Cipher.getInstance("DESede/ECB/NoPadding", "BC");
+      SecretKeySpec keyDes = new SecretKeySpec(resizeKey24(key), "DES");
+      cipher.init(Cipher.ENCRYPT_MODE, keyDes);
+      return cipher.doFinal(data);
+    } catch (GeneralSecurityException e) {
+      throw new RuntimeException("Could not encrypt data", e);
+    }
+  }
+
+  public static byte[] kcv3des(byte[] key) {
+    return Arrays.copyOf(ecb3des(key, NullBytes8), 3);
+  }
+
   /**
    * Generates a 3DES MAC for SCP02 communication
    *

lib/src/main/java/im/status/keycard/globalplatform/GlobalPlatformCommandSet.java

@@ -24,6 +24,7 @@ public class GlobalPlatformCommandSet {
   static final byte INS_DELETE = (byte) 0xE4;
   static final byte INS_INSTALL = (byte) 0xE6;
   static final byte INS_LOAD = (byte) 0xE8;
+  static final byte INS_PUT_KEY = (byte) 0xD8;
 
   static final byte SELECT_P1_BY_NAME = (byte) 0x04;
   static final byte EXTERNAL_AUTHENTICATE_P1 = (byte) 0x01;
@@ -37,7 +38,10 @@ public class GlobalPlatformCommandSet {
   private SCP02Keys cardKeys;
   private Session session;
 
-  private final byte[] testKey = Hex.decode("404142434445464748494a4b4c4d4e4f");
+  private final byte[] gpDefaultKey = Hex.decode("404142434445464748494a4b4c4d4e4f");
+  private final SCP02Keys gpDefaultKeys = new SCP02Keys(gpDefaultKey, gpDefaultKey, gpDefaultKey);
+
+  private final byte[] developmentKey = Hex.decode("c212e073ff8b4bbfaff4de8ab655221f");
 
   /**
    * Constructs a new command set with the given CardChannel.
@@ -46,7 +50,26 @@ public class GlobalPlatformCommandSet {
    */
   public GlobalPlatformCommandSet(CardChannel apduChannel) {
     this.apduChannel = apduChannel;
-    this.cardKeys = new SCP02Keys(testKey, testKey);
+    setCardKeys(developmentKey);
+  }
+
+  /**
+   * Sets the given key as all of ENC, MAC and DEK static keys, used to derive session keys.
+   * @param key the key
+   */
+  public void setCardKeys(byte[] key) {
+    setCardKeys(key, key, key);
+  }
+
+  /**
+   * Sets the the ENC, MAC and DEK static keys, used to derive session keys.
+   *
+   * @param encKey the ENC key
+   * @param macKey the MAC key
+   * @param dekKey the DEK key
+   */
+  public void setCardKeys(byte[] encKey, byte[] macKey, byte[] dekKey) {
+    this.cardKeys = new SCP02Keys(encKey, macKey, dekKey);;
   }
 
   /**
@@ -74,7 +97,12 @@ public class GlobalPlatformCommandSet {
     APDUCommand cmd = new APDUCommand(0x80, INS_INITIALIZE_UPDATE, 0, 0, hostChallenge, true);
     APDUResponse resp = apduChannel.send(cmd);
     if (resp.isOK()) {
-      this.session = SecureChannel.verifyChallenge(hostChallenge, this.cardKeys, resp);
+      try {
+        this.session = SecureChannel.verifyChallenge(hostChallenge, this.cardKeys, resp);
+      } catch(APDUException e) {
+        this.session = SecureChannel.verifyChallenge(hostChallenge, gpDefaultKeys, resp);
+        this.session.markAsUsingFallbackKeys();
+      }
       this.secureChannel = new SecureChannel(this.apduChannel, this.session.getKeys());
     }
 
@@ -103,18 +131,93 @@ public class GlobalPlatformCommandSet {
     return this.secureChannel.send(cmd);
   }
 
+
   /**
-   * Opens an SCP02 secure channel with default keys.
+   * Convenience method for openSecureChannel with auto key ugprade.
    *
    * @throws APDUException the card didn't respond 0x9000 to either INITIALIZE UPDATE or EXTERNAL AUTHENTICATE
    * @throws IOException communication error
    */
   public void openSecureChannel() throws APDUException, IOException {
+    openSecureChannel(true);
+  }
+
+  /**
+   * Opens an SCP02 secure channel. If with the current keys the card cryptogram cannot be verified, an attempt is made
+   * to use the default GlobalPlatform keys instead. This does not require additional commands to the card. In case
+   * the autoUpgradeKeys is set to true and the default GlobalPlatform keys were used, a PUT KEY command is sent to
+   * change the keys to the current ones.
+   *
+   * @param autoUpgradeKeys upgrade keys if default GP keys are loaded
+   * @throws APDUException the card didn't respond 0x9000 to either INITIALIZE UPDATE or EXTERNAL AUTHENTICATE
+   * @throws IOException communication error
+   */
+  public void openSecureChannel(boolean autoUpgradeKeys) throws APDUException, IOException {
     SecureRandom random = new SecureRandom();
     byte[] hostChallenge = new byte[8];
     random.nextBytes(hostChallenge);
     initializeUpdate(hostChallenge).checkOK();
     externalAuthenticate(hostChallenge).checkOK();
+
+    if (this.session.usesFallbackKeys() && autoUpgradeKeys) {
+      this.putSCP02Keys(this.cardKeys.getEncKeyData(), this.cardKeys.getMacKeyData(), this.cardKeys.getDekKeyData(), 0, 1).checkOK();
+    }
+  }
+
+  /**
+   * Sends a PUT KEY APDU to load or replace SCP02 keys. The key is used for all 3 of ENC, MAC and DEK.
+   *
+   * @param key the key to load
+   * @param oldKvn the KVN to replace, 0 to put a new key without replacing
+   * @param newKvn the KVN of the new keyset
+   * @return
+   * @throws IOException
+   */
+  public APDUResponse putSCP02Keys(byte[] key, int oldKvn, int newKvn) throws IOException {
+    return putSCP02Keys(key, key, key, oldKvn, newKvn);
+  }
+
+  /**
+   * Sends a PUT KEY APDU to load or replace SCP02 keys. The keys are assumed to be 3DES keys
+   *
+   * @param encKey the ENC key to load
+   * @param macKey the MAC key to load
+   * @param dekKey the DEK key to load
+   * @param oldKvn the KVN to replace, 0 to put a new key without replacing
+   * @param newKvn the KVN of the new keyset
+   * @return
+   * @throws IOException
+   */
+  public APDUResponse putSCP02Keys(byte[] encKey, byte[] macKey, byte[] dekKey, int oldKvn, int newKvn) throws IOException {
+    if (encKey.length != 16 || macKey.length != 16 || dekKey.length != 16){
+      throw new IllegalArgumentException("All keys must be 16-byte 3DES keys");
+    }
+
+    ByteArrayOutputStream bos = new ByteArrayOutputStream();
+    bos.write(newKvn);
+    writeSCP02Key(bos, encKey);
+    writeSCP02Key(bos, macKey);
+    writeSCP02Key(bos, dekKey);
+
+    APDUCommand cmd = new APDUCommand(0x84, INS_PUT_KEY, oldKvn, 0x81, bos.toByteArray());
+    return this.secureChannel.send(cmd);
+  }
+
+  /**
+   * writes an encrypted key for the PUT KEY command
+   * @param bos the output stream to write to
+   * @param key the key to encrypt and write
+   * @throws IOException if the ByteArrayOutputStream throws it (never)
+   */
+  private void writeSCP02Key(ByteArrayOutputStream bos, byte[] key) throws IOException {
+    byte[] encrypted = Crypto.ecb3des(session.getKeys().getDekKeyData(), key);
+    byte[] kcv = Crypto.kcv3des(key);
+
+    bos.write(0x80);
+    bos.write(encrypted.length);
+    bos.write(encrypted);
+    bos.write(kcv.length);
+    bos.write(kcv);
   }
 
   /**
@@ -127,6 +230,16 @@ public class GlobalPlatformCommandSet {
     return delete(Identifiers.getKeycardInstanceAID());
   }
 
+  /**
+   * Deletes the Keycard Cash applet instance.
+   *
+   * @return the card response
+   * @throws IOException communication error
+   */
+  public APDUResponse deleteCashInstance() throws IOException {
+    return delete(Identifiers.CASH_INSTANCE_AID);
+  }
+
   /**
    * Deletes the NDEF applet instance.
    *
@@ -157,6 +270,7 @@ public class GlobalPlatformCommandSet {
   public void deleteKeycardInstancesAndPackage() throws IOException, APDUException {
     deleteNDEFInstance().checkSW(APDUResponse.SW_OK, APDUResponse.SW_REFERENCED_DATA_NOT_FOUND);
     deleteKeycardInstance().checkSW(APDUResponse.SW_OK, APDUResponse.SW_REFERENCED_DATA_NOT_FOUND);
+    deleteCashInstance().checkSW(APDUResponse.SW_OK, APDUResponse.SW_REFERENCED_DATA_NOT_FOUND);
     deleteKeycardPackage().checkSW(APDUResponse.SW_OK, APDUResponse.SW_REFERENCED_DATA_NOT_FOUND);
   }
 
@@ -313,4 +427,25 @@ public class GlobalPlatformCommandSet {
   public APDUResponse installKeycardApplet() throws IOException {
     return installForInstall(Identifiers.PACKAGE_AID, Identifiers.KEYCARD_AID, Identifiers.getKeycardInstanceAID(), new byte[0]);
   }
+
+  /**
+   * Installs the Cash applet.
+   *
+   * @param cashData the initial Cash data. Can be a zero-length array but not null
+   * @return the card response
+   * @throws IOException communication error.
+   */
+  public APDUResponse installCashApplet(byte[] cashData) throws IOException {
+    return installForInstall(Identifiers.PACKAGE_AID, Identifiers.CASH_AID, Identifiers.CASH_INSTANCE_AID, cashData);
+  }
+
+  /**
+   * Installs the Cash applet.
+   *
+   * @return the card response
+   * @throws IOException communication error.
+   */
+  public APDUResponse installCashApplet() throws IOException {
+    return installCashApplet(new byte[0]);
+  }
 }

lib/src/main/java/im/status/keycard/globalplatform/SCP02Keys.java

@@ -6,16 +6,19 @@ package im.status.keycard.globalplatform;
 public class SCP02Keys {
   public byte[] encKeyData;
   public byte[] macKeyData;
+  public byte[] dekKeyData;
 
   /**
    * Constructor. Takes the ENC and MAC keys.
    *
    * @param encKeyData encryption key
    * @param macKeyData mac key
+   * @param dekKeyData data encryption key
    */
-  public SCP02Keys(byte[] encKeyData, byte[] macKeyData) {
+  public SCP02Keys(byte[] encKeyData, byte[] macKeyData, byte[] dekKeyData) {
     this.encKeyData = encKeyData;
     this.macKeyData = macKeyData;
+    this.dekKeyData = dekKeyData;
   }
 
   /**
@@ -34,4 +37,13 @@ public class SCP02Keys {
   public byte[] getMacKeyData() {
     return macKeyData;
   }
+
+  /**
+   * The DEK key
+   *
+   * @return the DEK key
+   */
+  public byte[] getDekKeyData() {
+    return dekKeyData;
+  }
 }

lib/src/main/java/im/status/keycard/globalplatform/SecureChannel.java

@@ -8,7 +8,7 @@ import im.status.keycard.io.APDUResponse;
 import im.status.keycard.io.CardChannel;
 
 /**
- * An SCP02 Secure Channel. Wraps a CardChannel to allow transparent handling of the scure channel.
+ * An SCP02 Secure Channel. Wraps a CardChannel to allow transparent handling of the secure channel.
  */
 public class SecureChannel {
   private CardChannel channel;
@@ -77,8 +77,9 @@ public class SecureChannel {
 
     byte[] sessionEncKey = Crypto.deriveSCP02SessionKey(cardKeys.getEncKeyData(), seq, DERIVATION_PURPOSE_ENC);
     byte[] sessionMacKey = Crypto.deriveSCP02SessionKey(cardKeys.getMacKeyData(), seq, DERIVATION_PURPOSE_MAC);
+    byte[] sessionDekKey = Crypto.deriveSCP02SessionKey(cardKeys.getDekKeyData(), seq, DERIVATION_PURPOSE_DEK);
 
-    SCP02Keys sessionKeys = new SCP02Keys(sessionEncKey, sessionMacKey);
+    SCP02Keys sessionKeys = new SCP02Keys(sessionEncKey, sessionMacKey, sessionDekKey);
 
     boolean verified = Crypto.verifyCryptogram(sessionKeys.getEncKeyData(), hostChallenge, cardChallenge, cardCryptogram);
     if (!verified) {

lib/src/main/java/im/status/keycard/globalplatform/Session.java

@@ -6,6 +6,7 @@ package im.status.keycard.globalplatform;
 public class Session {
   private SCP02Keys keys;
   private byte[] cardChallenge;
+  private boolean fallbackKeys;
 
   /**
    * Constructs the SCP02 session.
@@ -16,6 +17,7 @@ public class Session {
   public Session(SCP02Keys keys, byte[] cardChallenge) {
     this.keys = keys;
     this.cardChallenge = cardChallenge;
+    this.fallbackKeys = false;
   }
 
   /**
@@ -33,4 +35,21 @@ public class Session {
   public byte[] getCardChallenge() {
     return cardChallenge;
   }
+
+  /**
+   * Marks this session as using a fallback keyset.
+   */
+  public void markAsUsingFallbackKeys() {
+    fallbackKeys = true;
+  }
+
+  /**
+   * True if a fallback keyset is being used.
+   *
+   * @return true or false
+   */
+  public boolean usesFallbackKeys() {
+    return fallbackKeys;
+  }
+
 }

lib/src/main/java/im/status/keycard/io/APDUResponse.java

@@ -88,6 +88,35 @@ public class APDUResponse {
     }
   }
 
+  /**
+   * Asserts that the SW is 0x9000. Throws an exception with the given message if it isn't
+   *
+   * @param message the error message
+   * @return this object, to simplify chaining
+   * @throws APDUException if the SW is not 0x9000
+   */
+  public APDUResponse checkOK(String message) throws APDUException {
+    return checkSW(message, SW_OK);
+  }
+
+  /**
+   * Asserts that the SW is contained in the given list. Throws an exception with the given message if it isn't.
+   *
+   * @param message the error message
+   * @param codes the list of SWs to match.
+   * @return this object, to simplify chaining
+   * @throws APDUException if the SW is not 0x9000
+   */
+  public APDUResponse checkSW(String message, int... codes) throws APDUException {
+    for (int code : codes) {
+      if (this.sw == code) {
+        return this;
+      }
+    }
+
+    throw new APDUException(this.sw, message);
+  }
+
   /**
    * Checks response from an authentication command (VERIFY PIN, UNBLOCK PUK)
    *

lib/src/main/java/im/status/keycard/io/LedgerUtil.java

@@ -0,0 +1,153 @@
+package im.status.keycard.io;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+public class LedgerUtil {
+  private static final int LEDGER_DEFAULT_CHANNEL = 1;
+  private static final int TAG_APDU = 0x05;
+
+  private LedgerUtil() {}
+
+  public interface Callback {
+    void write(byte[] chunk) throws IOException;
+    void read(byte[] chunk) throws IOException;
+  }
+
+  public static APDUResponse send(APDUCommand cmd, int segmentSize, boolean channelInfo, LedgerUtil.Callback cb) throws IOException {
+    int offset = 0;
+
+    byte[] command = LedgerUtil.wrapCommandAPDU(cmd.serialize(), segmentSize, channelInfo);
+    byte[] chunk = new byte[segmentSize];
+
+    while(offset != command.length) {
+      System.arraycopy(command, offset, chunk, 0, segmentSize);
+      cb.write(chunk);
+      offset += segmentSize;
+    }
+
+    ByteArrayOutputStream response = new ByteArrayOutputStream();
+    byte[] responseData = null;
+
+    while ((responseData = LedgerUtil.unwrapResponseAPDU(response.toByteArray(), segmentSize, channelInfo)) == null) {
+      cb.read(chunk);
+      response.write(chunk, 0, segmentSize);
+    }
+
+    return new APDUResponse(responseData);
+  }
+
+  private static byte[] unwrapResponseAPDU(byte[] data, int segmentSize, boolean channelInfo) throws IOException {
+    if ((data == null) || (data.length < 7 + 5)) {
+      return null;
+    }
+
+    int sequenceIdx = 0;
+    int offset = checkResponseHeader(data, 0, sequenceIdx, channelInfo);
+
+    int  responseLength = ((data[offset++] & 0xff) << 8);
+    responseLength |= (data[offset++] & 0xff);
+
+    if (data.length < 7 + responseLength) {
+      return null;
+    }
+
+    ByteArrayOutputStream response = new ByteArrayOutputStream();
+
+    int headerSize = channelInfo ? 5 : 3;
+    int initialHeaderSize = headerSize + 2;
+
+    int blockSize = (responseLength > segmentSize - initialHeaderSize ? segmentSize - initialHeaderSize : responseLength);
+    response.write(data, offset, blockSize);
+    offset += blockSize;
+
+    while (response.size() != responseLength) {
+      sequenceIdx++;
+
+      if (offset == data.length) {
+        return null;
+      }
+
+      offset = checkResponseHeader(data, offset, sequenceIdx, channelInfo);
+
+      blockSize = (responseLength - response.size() > segmentSize - headerSize ? segmentSize - headerSize : responseLength - response.size());
+      if (blockSize > data.length - offset) {
+        return null;
+      }
+      response.write(data, offset, blockSize);
+      offset += blockSize;
+    }
+
+    return response.toByteArray();
+  }
+
+  private static int checkResponseHeader(byte[] data, int offset, int sequenceIdx, boolean channelInfo) throws IOException {
+    if (channelInfo) {
+      if (data[offset++] != (LEDGER_DEFAULT_CHANNEL >> 8)) {
+        throw new IOException("Invalid channel");
+      }
+
+      if (data[offset++] != (LEDGER_DEFAULT_CHANNEL & 0xff)) {
+        throw new IOException("Invalid channel");
+      }
+    }
+
+    if (data[offset++] != TAG_APDU) {
+      throw new IOException("Invalid tag");
+    }
+
+    if (data[offset++] != (sequenceIdx >> 8)) {
+      throw new IOException("Invalid sequence");
+    }
+
+    if (data[offset++] != (sequenceIdx & 0xff)) {
+      throw new IOException("Invalid sequence");
+    }
+    return offset;
+  }
+
+  private static byte[] wrapCommandAPDU(byte[] command, int segmentSize, boolean channelInfo) {
+    ByteArrayOutputStream output = new ByteArrayOutputStream();
+
+    int headerSize = channelInfo ? 5 : 3;
+    int initialHeaderSize = headerSize + 2;
+
+    int sequenceIdx = 0;
+    int offset = 0;
+    writeCommandHeader(output, sequenceIdx, channelInfo);
+    sequenceIdx++;
+
+    output.write(command.length >> 8);
+    output.write(command.length);
+    int blockSize = (command.length > (segmentSize - initialHeaderSize) ? (segmentSize - initialHeaderSize) : command.length);
+    output.write(command, offset, blockSize);
+    offset += blockSize;
+
+    while (offset != command.length) {
+      writeCommandHeader(output, sequenceIdx, channelInfo);
+      sequenceIdx++;
+
+      blockSize = ((command.length - offset) > (segmentSize - headerSize) ? (segmentSize - headerSize) : (command.length - offset));
+      output.write(command, offset, blockSize);
+      offset += blockSize;
+    }
+
+    if ((output.size() % segmentSize) != 0) {
+      byte[] padding = new byte[segmentSize - (output.size() % segmentSize)];
+      output.write(padding, 0, padding.length);
+    }
+
+    return output.toByteArray();
+  }
+
+  private static void writeCommandHeader(ByteArrayOutputStream output, int sequenceIdx, boolean channelInfo) {
+    if (channelInfo) {
+      output.write(LEDGER_DEFAULT_CHANNEL >> 8);
+      output.write(LEDGER_DEFAULT_CHANNEL);
+    }
+
+    output.write(TAG_APDU);
+    output.write(sequenceIdx >> 8);
+    output.write(sequenceIdx);
+  }
+}