Merge pull request #60 from status-im/reduce-nvm-writes

JCOP4 compatibility + reduce NVM writes

buildSrc/src/main/java/im/status/keycard/build/InstallTask.java

@@ -64,11 +64,11 @@ public void blockLoaded(int loadedBlock, int blockCount) {
         }
       });
       logger.info("Installing the Keycard Applet");
-      cmdSet.installKeycardApplet();
+      cmdSet.installKeycardApplet().checkOK();
       logger.info("Installing the NDEF Applet");
-      cmdSet.installNDEFApplet(new byte[0]);
+      cmdSet.installNDEFApplet(new byte[0]).checkOK();
       logger.info("Installing the Cash Applet");
-      cmdSet.installCashApplet();
+      cmdSet.installCashApplet().checkOK();
     } catch (IOException e) {
       throw new GradleException("I/O error", e);
     } catch (APDUException e) {

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

@@ -40,7 +40,7 @@ public static void install(byte[] bArray, short bOffset, byte bLength) {
    */
   public CashApplet(byte[] bArray, short bOffset, byte bLength) {
     crypto = new Crypto();
-    secp256k1 = new SECP256k1(crypto);
+    secp256k1 = new SECP256k1();
 
     keypair = new KeyPair(KeyPair.ALG_EC_FP, SECP256k1.SECP256K1_KEY_SIZE);
     publicKey = (ECPublicKey) keypair.getPublic();

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

@@ -167,8 +167,7 @@ public static void install(byte[] bArray, short bOffset, byte bLength) {
    */
   public KeycardApplet(byte[] bArray, short bOffset, byte bLength) {
     crypto = new Crypto();
-    secp256k1 = new SECP256k1(crypto);
-    secureChannel = new SecureChannel(PAIRING_MAX_CLIENT_COUNT, crypto, secp256k1);
+    secp256k1 = new SECP256k1();
 
     uid = new byte[UID_LENGTH];
     crypto.random.generateData(uid, (short) 0, UID_LENGTH);
@@ -199,7 +198,7 @@ public KeycardApplet(byte[] bArray, short bOffset, byte bLength) {
 
     derivationOutput = JCSystem.makeTransientByteArray((short) (Crypto.KEY_SECRET_SIZE + CHAIN_CODE_SIZE), JCSystem.CLEAR_ON_RESET);
 
-    data = new byte[MAX_DATA_LENGTH + 1];
+    data = new byte[(short)(MAX_DATA_LENGTH + 1)];
 
     register(bArray, (short) (bOffset + 1), bArray[bOffset]);
   }
@@ -214,6 +213,9 @@ public KeycardApplet(byte[] bArray, short bOffset, byte bLength) {
   public void process(APDU apdu) throws ISOException {
     // If we have no PIN it means we still have to initialize the applet.
     if (pin == null) {
+      if (secureChannel == null) {
+        secureChannel = new SecureChannel(PAIRING_MAX_CLIENT_COUNT, crypto, secp256k1);
+      }
       processInit(apdu);
       return;
     }
@@ -374,7 +376,6 @@ private void selectApplet(APDU apdu) {
     pin.reset();
     puk.reset();
     secureChannel.reset();
-    secureChannel.updateSecureChannelCounter();
 
     byte[] apduBuffer = apdu.getBuffer();
 

src/main/java/im/status/keycard/SECP256k1.java

@@ -54,14 +54,12 @@ public class SECP256k1 {
 
 
   private KeyAgreement ecPointMultiplier;
-  private Crypto crypto;
   ECPrivateKey tmpECPrivateKey;
 
   /**
    * Allocates objects needed by this class. Must be invoked during the applet installation exactly 1 time.
    */
-  SECP256k1(Crypto crypto) {
-    this.crypto = crypto;
+  SECP256k1() {
     this.ecPointMultiplier = KeyAgreement.getInstance(ALG_EC_SVDP_DH_PLAIN_XY, false);
     this.tmpECPrivateKey = (ECPrivateKey) KeyBuilder.buildKey(KeyBuilder.TYPE_EC_FP_PRIVATE, SECP256K1_KEY_SIZE, false);
     setCurveParameters(tmpECPrivateKey);

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

@@ -13,7 +13,6 @@ public class SecureChannel {
   public static final short PAIRING_KEY_LENGTH = SC_SECRET_LENGTH + 1;
   public static final short SC_BLOCK_SIZE = Crypto.AES_BLOCK_SIZE;
   public static final short SC_OUT_OFFSET = ISO7816.OFFSET_CDATA + (SC_BLOCK_SIZE * 2);
-  public static final short SC_COUNTER_MAX = 100;
 
   public static final byte INS_OPEN_SECURE_CHANNEL = 0x10;
   public static final byte INS_MUTUALLY_AUTHENTICATE = 0x11;
@@ -33,8 +32,6 @@ public class SecureChannel {
   private byte[] secret;
   private byte[] pairingSecret;
 
-  private short scCounter;
-
   /*
    * To avoid overhead, the pairing keys are stored in a plain byte array as sequences of 33-bytes elements. The first
    * byte is 0 if the slot is free and 1 if used. The following 32 bytes are the actual key data.
@@ -59,13 +56,14 @@ public SecureChannel(byte pairingLimit, Crypto crypto, SECP256k1 secp256k1) {
     scEncKey = (AESKey) KeyBuilder.buildKey(KeyBuilder.TYPE_AES_TRANSIENT_DESELECT, KeyBuilder.LENGTH_AES_256, false);
     scMacKey = (AESKey) KeyBuilder.buildKey(KeyBuilder.TYPE_AES_TRANSIENT_DESELECT, KeyBuilder.LENGTH_AES_256, false);
 
+    secret = JCSystem.makeTransientByteArray((short)(SC_SECRET_LENGTH * 2), JCSystem.CLEAR_ON_DESELECT);
+    pairingKeys = new byte[(short)(PAIRING_KEY_LENGTH * pairingLimit)];
+
     scKeypair = new KeyPair(KeyPair.ALG_EC_FP, SC_KEY_LENGTH);
     secp256k1.setCurveParameters((ECKey) scKeypair.getPrivate());
     secp256k1.setCurveParameters((ECKey) scKeypair.getPublic());
     scKeypair.genKeyPair();
 
-    secret = JCSystem.makeTransientByteArray((short)(SC_SECRET_LENGTH * 2), JCSystem.CLEAR_ON_DESELECT);
-    pairingKeys = new byte[(short)(PAIRING_KEY_LENGTH * pairingLimit)];
     remainingSlots = pairingLimit;
 
   }
@@ -391,18 +389,6 @@ public byte getRemainingPairingSlots() {
     return remainingSlots;
   }
 
-  /**
-   * Called before sending the public key to the client, gives a chance to change keys if needed.
-   */
-  public void updateSecureChannelCounter() {
-    if (scCounter < SC_COUNTER_MAX) {
-      scCounter++;
-    } else {
-      scKeypair.genKeyPair();
-      scCounter = 0;
-    }
-  }
-
   /**
    * Resets the Secure Channel, invalidating the current session. If no session is opened, this does nothing.
    */

src/test/java/im/status/keycard/KeycardTest.java

@@ -289,19 +289,7 @@ void openSecureChannelTest() throws Exception {
     response = cmdSet.getStatus(KeycardApplet.GET_STATUS_P1_APPLICATION);
     assertEquals(0x9000, response.getSw());
 
-    // Verify that the keys are changed correctly. Since we do not know the internal counter we just iterate until that
-    // happens for a maximum of SC_COUNTER_MAX times
-    byte[] initialKey = new ApplicationInfo(cmdSet.select().getData()).getSecureChannelPubKey();
 
-    for (int i = 0; i < SecureChannel.SC_COUNTER_MAX; i++) {
-      byte[] otherKey = new ApplicationInfo(cmdSet.select().getData()).getSecureChannelPubKey();
-
-      if (!Arrays.equals(initialKey, otherKey)) {
-        secureChannel.generateSecret(otherKey);
-        cmdSet.autoOpenSecureChannel();
-        break;
-      }
-    }
   }
 
   @Test
@@ -384,7 +372,7 @@ void pairTest() throws Exception {
     cmdSet.openSecureChannel(secureChannel.getPairingIndex(), secureChannel.getPublicKey());
 
     // Pair multiple indexes
-    for (int i = 1; i < 5; i++) {
+    for (int i = 1; i < KeycardApplet.PAIRING_MAX_CLIENT_COUNT; i++) {
       cmdSet.autoPair(sharedSecret);
       assertEquals(i, secureChannel.getPairingIndex());
       cmdSet.autoOpenSecureChannel();
@@ -403,7 +391,7 @@ void pairTest() throws Exception {
       assertEquals(0x9000, response.getSw());
     }
 
-    for (byte i = 0; i < 4; i++) {
+    for (byte i = 0; i < (KeycardApplet.PAIRING_MAX_CLIENT_COUNT - 1); i++) {
       response = cmdSet.unpair(i);
       assertEquals(0x9000, response.getSw());
     }