From 171220bd799b04d1bc1ff86dca8532e3efd28804 Mon Sep 17 00:00:00 2001
From: Michele Balistreri <michele@bitgamma.com>
Date: Fri, 14 Dec 2018 13:21:36 +0300
Subject: [PATCH] change AIDs

---
 .../im/status/keycard/applet/Identifiers.java | 30 +++++++++++++++----
 .../keycard/applet/KeycardCommandSet.java     | 18 +++++++++--
 2 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/lib/src/main/java/im/status/keycard/applet/Identifiers.java b/lib/src/main/java/im/status/keycard/applet/Identifiers.java
index adaf606..5a20ca0 100644
--- a/lib/src/main/java/im/status/keycard/applet/Identifiers.java
+++ b/lib/src/main/java/im/status/keycard/applet/Identifiers.java
@@ -2,21 +2,39 @@ package im.status.keycard.applet;
 
 import org.bouncycastle.util.encoders.Hex;
 
+import java.util.Arrays;
+
 public class Identifiers {
-  public static final byte[] PACKAGE_AID = Hex.decode("53746174757357616C6C6574");
+  public static final byte[] PACKAGE_AID = Hex.decode("A0000008040001");
 
-  public static final byte[] KEYCARD_AID = Hex.decode("53746174757357616C6C6574417070");
+  public static final byte[] KEYCARD_AID = Hex.decode("A000000804000101");
+  public static final int KEYCARD_DEFAULT_INSTANCE_IDX = 1;
 
-  public static final byte[] NDEF_AID = Hex.decode("53746174757357616C6C65744E4643");
+  public static final byte[] NDEF_AID = Hex.decode("A000000804000102");
   public static final byte[] NDEF_INSTANCE_AID = Hex.decode("D2760000850101");
 
   /**
-   * Gets the instance AID of the Keycard applet. Since multiple instances this is a method instead of a constant.
-   * Soon a method taking an additional instance index will be added.
+   * Gets the instance AID of the default instance of the Keycard applet.
    *
    * @return the instance AID of the Keycard applet
    */
   public static byte[] getKeycardInstanceAID() {
-    return KEYCARD_AID;
+    return getKeycardInstanceAID(KEYCARD_DEFAULT_INSTANCE_IDX);
+  }
+
+  /**
+   * Gets the instance AID of the Keycard applet with the given index. Since multiple instances of the Keycard applet
+   * could be installed in parallel, this method allows selecting a specific instance. The index is between 01 and ff
+   *
+   * @return the instance AID of the Keycard applet
+   */
+  public static byte[] getKeycardInstanceAID(int instanceIdx) {
+    if (instanceIdx < 0x01 || instanceIdx > 0xff) {
+      throw new IllegalArgumentException("The instance index must be between 1 and 255");
+    }
+
+    byte[] instanceAID = Arrays.copyOf(KEYCARD_AID, KEYCARD_AID.length + 1);
+    instanceAID[KEYCARD_AID.length] = (byte) instanceIdx;
+    return instanceAID;
   }
 }
diff --git a/lib/src/main/java/im/status/keycard/applet/KeycardCommandSet.java b/lib/src/main/java/im/status/keycard/applet/KeycardCommandSet.java
index 80b929b..afabb3d 100644
--- a/lib/src/main/java/im/status/keycard/applet/KeycardCommandSet.java
+++ b/lib/src/main/java/im/status/keycard/applet/KeycardCommandSet.java
@@ -95,14 +95,26 @@ public class KeycardCommandSet {
   }
 
   /**
-   * Selects the applet. 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.
+   * Selects the default instance of the Keycard applet. 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.getKeycardInstanceAID());
+    return select(Identifiers.KEYCARD_DEFAULT_INSTANCE_IDX);
+  }
+
+  /**
+   * Selects a Keycard 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.
+   *
+   * @param instanceIdx the instance index
+   * @return the raw card response
+   * @throws IOException communication error
+   */
+  public APDUResponse select(int instanceIdx) throws IOException {
+    APDUCommand selectApplet = new APDUCommand(0x00, 0xA4, 4, 0, Identifiers.getKeycardInstanceAID(instanceIdx));
     APDUResponse resp =  apduChannel.send(selectApplet);
 
     if (resp.getSw() == 0x9000) {