Fix for Extended APDUs

Not all Java Cards that support extended APDUs have APDU buffer
lengths long enough to include the attestation certificate. This
causes registration to fail when extended APDUs are used, as is the
case with iOS.

The fix is to build the extended responses incrementally instead of
staging them all at once in the APDU buffer.

src/main/java/com/ledger/u2f/U2FApplet.java

@@ -190,18 +190,19 @@ private void handleEnroll(APDU apdu) throws ISOException {
         attestationSignature.update(scratch, SCRATCH_KEY_HANDLE_OFFSET, keyHandleLength);
         attestationSignature.update(scratch, SCRATCH_PUBLIC_KEY_OFFSET, (short)65);
         outOffset = (short)(ENROLL_PUBLIC_KEY_OFFSET + 65 + 1 + keyHandleLength);
+        short signatureSize = attestationSignature.sign(buffer, (short)0, (short)0, scratch, SCRATCH_SIGNATURE_OFFSET);
+
         if (extendedLength) {
             // If using extended length, the message can be completed and sent immediately
             scratch[SCRATCH_TRANSPORT_STATE] = TRANSPORT_EXTENDED;
-            outOffset = Util.arrayCopyNonAtomic(scratch, SCRATCH_PAD, buffer, (short)0, outOffset);
-            outOffset = Util.arrayCopyNonAtomic(attestationCertificate, (short)0, buffer, outOffset, (short)attestationCertificate.length);
-            short signatureSize = attestationSignature.sign(buffer, (short)0, (short)0, buffer, outOffset);
-            outOffset += signatureSize;
-            apdu.setOutgoingAndSend((short)0, outOffset);
+            apdu.setOutgoing();
+            apdu.setOutgoingLength((short)(outOffset + attestationCertificate.length + signatureSize));
+            apdu.sendBytesLong(scratch, SCRATCH_PAD, outOffset);
+            apdu.sendBytesLong(attestationCertificate, (short)0, (short)attestationCertificate.length);
+            apdu.sendBytesLong(scratch, SCRATCH_SIGNATURE_OFFSET, signatureSize);
         }
         else {
             // Otherwise, keep the signature and proceed to send the first chunk
-            short signatureSize = attestationSignature.sign(buffer, (short)0, (short)0, scratch, SCRATCH_SIGNATURE_OFFSET);
             scratch[SCRATCH_TRANSPORT_STATE] = TRANSPORT_NOT_EXTENDED;
             Util.setShort(scratch, SCRATCH_CURRENT_OFFSET, (short)0);
             Util.setShort(scratch, SCRATCH_SIGNATURE_LENGTH, signatureSize);
@@ -285,8 +286,9 @@ private void handleSign(APDU apdu) throws ISOException {
         if (extendedLength) {
             // If using extended length, the message can be completed and sent immediately
             scratch[SCRATCH_TRANSPORT_STATE] = TRANSPORT_EXTENDED;
-            Util.arrayCopyNonAtomic(scratch, SCRATCH_PAD, buffer, (short)0, outOffset);
-            apdu.setOutgoingAndSend((short)0, (short)(outOffset - SCRATCH_PAD));
+            apdu.setOutgoing();
+            apdu.setOutgoingLength((short)(outOffset - SCRATCH_PAD));
+            apdu.sendBytesLong(scratch, SCRATCH_PAD, (short)(outOffset - SCRATCH_PAD));
         }
         else {
             // Otherwise send the first chunk