implement GET DATA + STORE DATA

src/main/java/im/status/keycard/KeycardApplet.java

@@ -25,6 +25,8 @@ public class KeycardApplet extends Applet {
   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;
 
   static final short SW_REFERENCED_DATA_NOT_FOUND = (short) 0x6A88;
 
@@ -35,6 +37,7 @@ public class KeycardApplet extends Applet {
   static final byte KEY_PATH_MAX_DEPTH = 10;
   static final byte PAIRING_MAX_CLIENT_COUNT = 5;
   static final byte UID_LENGTH = 16;
+  static final byte MAX_DATA_LENGTH = 127;
 
   static final short CHAIN_CODE_SIZE = 32;
   static final short KEY_UID_LENGTH = 32;
@@ -141,6 +144,8 @@ public class KeycardApplet extends Applet {
 
   private byte[] derivationOutput;
 
+  private byte[] data;
+
   /**
    * Invoked during applet installation. Creates an instance of this class. The installation parameters are passed in
    * the given buffer.
@@ -201,6 +206,8 @@ public class KeycardApplet extends Applet {
 
     derivationOutput = JCSystem.makeTransientByteArray((short) (Crypto.KEY_SECRET_SIZE + CHAIN_CODE_SIZE), JCSystem.CLEAR_ON_RESET);
 
+    data = new byte[MAX_DATA_LENGTH + 1];
+
     register(bArray, (short) (bOffset + 1), bArray[bOffset]);
   }
 
@@ -283,6 +290,12 @@ public class KeycardApplet extends Applet {
         case INS_EXPORT_KEY:
           exportKey(apdu);
           break;
+        case INS_GET_DATA:
+          getData(apdu);
+          break;
+        case INS_STORE_DATA:
+          storeData(apdu);
+          break;
         default:
           ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
           break;
@@ -1434,6 +1447,52 @@ public class KeycardApplet extends Applet {
     secureChannel.respond(apdu, len, ISO7816.SW_NO_ERROR);
   }
 
+  /**
+   * Processes the GET DATA command.
+   *
+   * @param apdu the JCRE-owned APDU object.
+   */
+  private void getData(APDU apdu) {
+    byte[] apduBuffer = apdu.getBuffer();
+
+    if (secureChannel.isOpen()) {
+      secureChannel.preprocessAPDU(apduBuffer);
+    }
+
+    short outLen = Util.makeShort((byte) 0x00, data[0]);
+    Util.arrayCopyNonAtomic(data, (short) 1, apduBuffer, SecureChannel.SC_OUT_OFFSET, outLen);
+
+    if (secureChannel.isOpen()) {
+      secureChannel.respond(apdu, outLen, ISO7816.SW_NO_ERROR);
+    } else {
+      apdu.setOutgoingAndSend(SecureChannel.SC_OUT_OFFSET, outLen);
+    }
+  }
+
+  /**
+   * Processes the STORE DATA command. Requires an open secure channel and the PIN to be verified.
+   *
+   * @param apdu the JCRE-owned APDU object.
+   */
+  private void storeData(APDU apdu) {
+    byte[] apduBuffer = apdu.getBuffer();
+    secureChannel.preprocessAPDU(apduBuffer);
+
+    if (!pin.isValidated()) {
+      ISOException.throwIt(ISO7816.SW_CONDITIONS_NOT_SATISFIED);
+    }
+
+    short dataLen = Util.makeShort((byte) 0x00, apduBuffer[ISO7816.OFFSET_LC]);
+
+    if (dataLen > MAX_DATA_LENGTH) {
+      ISOException.throwIt(ISO7816.SW_WRONG_DATA);
+    }
+
+    JCSystem.beginTransaction();
+    Util.arrayCopy(apduBuffer, ISO7816.OFFSET_LC, data, (short) 0, (short)(dataLen + 1));
+    JCSystem.commitTransaction();
+  }
+
   /**
    * Utility method to verify if all the bytes in the buffer between off (included) and off + len (excluded) are digits.
    *