fix bugs

src/main/java/com/josh/vku2f/CTAP2.java

@@ -471,13 +471,18 @@ public class CTAP2 extends Applet implements ExtendedLength {
 		// | ----- 32 byte is H(H(IV)||H(Nonce)) ----- | ----- 32 byte HMAC -----|
 		// for reduce the mem/flash usage, I reuse the buffer to store the retrun value
 		// put encryptedCx
-		int counter = hkdf.getIteration();
+		short counter = hkdf.getIteration();
 		// using CBOR Encoder to assemble the return value
 		// H(H(IV) || H(Nonce)) ret1[0:31] 32 bytes
 		// Nonce 32 bytes ret2[0:31]
 		// HMAC(output_key, H(IV||Nonce)) 32 bytes ret2[32:64]
 		// Iteration(Counter) 4 bytes integer : counter
 		// total return length : 100 bytes
+
+		/**	TODO
+		 * 		Using CBOREncoding to assemble the return value
+		 */
+
 	}
 	/**
 	 * for alternative framework purpose

src/main/java/com/josh/vku2f/HKDF.java

 package com.josh.vku2f;
 
 import javacard.framework.*;
+
 public class HKDF
 {
     private byte[] ikm;
@@ -9,48 +10,55 @@ public class HKDF
     private HMAC hmac;
     private byte[] temp = JCSystem.makeTransientByteArray((short)32, JCSystem.CLEAR_ON_RESET);
     private byte[] tempPrk;
-    private int iteration;
+    private short iteration;
+    private boolean init;
     private byte[] counter = new byte[1];
     public HKDF(byte[] key, byte[] iv){
-        this.iteration = 0;
         this.ikm = new byte[key.length];
         this.iv = new byte[iv.length];
-        this.prev_key = new byte[32];
         Util.arrayCopy(key, (short)0, this.ikm, (short)0, (short)key.length);
         Util.arrayCopy(iv, (short)0, this.iv, (short)0, (short)iv.length);
         hmac = new HMAC(new byte[32]);
         tempPrk = JCSystem.makeTransientByteArray((short)iv.length, JCSystem.CLEAR_ON_RESET);
-        Util.arrayCopy(this.iv, (short)0, this.prev_key, (short)0, (short)iv.length);
+        prev_key = new byte[32];
+        this.iteration = 0;
+        this.init = true;
     }
-    public void setIteration(int _iteration){
+    public void setIteration(short _iteration){
         this.iteration = _iteration;
+        this.init = false;
     }
-    public int getIteration(){
+    public short getIteration(){
         return this.iteration;
     }
     public void getOutputKey(byte[] info, short length, byte[] output, short offset){
         getPRK(tempPrk, (short)0);
         expand(tempPrk, info, length, output, offset);
-
     }
     public void getNextOutputKey(byte[] info, short length, byte[] output, short offset){
+        if(this.init == false){
+            getPRK(tempPrk, (short)0);
+        }
         expand(prev_key, info, length, output, offset);
-
     }
-    public void getPRK( byte[] output, short offset){
+    public void getPRK(byte[] output, short offset){
         //Util.arrayCopy(iv, (short)0, tempPrk, (short)0, (short)iv.length);
         Util.arrayCopy(this.ikm ,(short)0, tempPrk, (short)0, (short)32);
-        for(short i=0; i<this.iteration; i++){
+        for(short i=0; i< this.iteration; i++){
             extract(iv, tempPrk, tempPrk, (short)0);
         }
         Util.arrayCopy(tempPrk, (short)0, output, (short)0, (short)tempPrk.length);
         Util.arrayCopy(tempPrk, (short)0, prev_key, (short)0, (short)prev_key.length);
+        this.init = true;
     }
     public void nextPRK(byte[] output, short offset){
+        if(this.init == false){
+            getPRK(tempPrk, (short)0);
+        }
         Util.arrayCopy(this.prev_key, (short)0, tempPrk, (short)0, (short)this.prev_key.length);
         extract(tempPrk, this.ikm, output, (short)offset);
         Util.arrayCopy(output, (short)offset, this.prev_key, (short)0, (short)32);
-        this.iteration++;
+
     }
     private void extract(byte[] key, byte[] msg, byte[] output, short offset){
         hmac.setKey(key);
@@ -59,7 +67,7 @@ public class HKDF
     }
     // prf: pseudo random function
     private void expand(byte[] prf, byte[] info, short length, byte[] output, short offset){
-        if(length/32>=255 && length%32>0){
+        if((short)(length/32) >= (short)255 && (short)length % (short)32 > (short)0){
             // up to 255 rounds for hmac operation
             // which means the max output length is 255*32=8160
             return;
@@ -74,9 +82,10 @@ public class HKDF
             hmac.setKey(prf);
             hmac.update(info, (short)0, (short)info.length);
             counter[0] = (byte)(i+1);
-            hmac.update(counter, (short)0, (short)info.length);
-            if(i<N-1)
-                hmac.doFinal(output, (short)(i*32+offset));
+            hmac.update(counter, (short)0, (short)counter.length);
+            if( i < (short)(N-1)) {
+                hmac.doFinal(output, (short) (i * 32 + offset));
+            }
             else{
                 if(remainder==0)
                     hmac.doFinal(output, (short)(i*32+offset));

src/main/java/com/josh/vku2f/HMAC.java

@@ -34,7 +34,7 @@ public class HMAC
         Util.arrayFillNonAtomic(okeypad, prkLength, (short)(okeypad.length-prkLength), (byte)0x5c);
     }
     public void update(byte[] newMsg, short offset, short length){
-        if(length + msgCursor > msg.length)
+        if((short) (length + msgCursor) > (short)msg.length)
             return;
         Util.arrayCopy(newMsg, offset, msg, msgCursor, length);
         msgCursor+=(short)newMsg.length;
@@ -44,7 +44,7 @@ public class HMAC
         sha256.doFinal(msg, (short)0, msgCursor, output, offset);
 
         sha256.update(okeypad, (short)0, (short)okeypad.length);
-        sha256.doFinal(output, (short)0, (short)32, output, offset);
+        sha256.doFinal(output, (short)offset, (short)32, output, offset);
 
         msgCursor = (short)0;
     }