Fix 14443 Type B generation of wrapped ATR

remote-reader/app/src/main/java/com/vsmartcard/remotesmartcardreader/app/screaders/NFCReader.java

@@ -25,6 +25,8 @@
 import android.nfc.NfcAdapter;
 import android.nfc.Tag;
 import android.nfc.tech.IsoDep;
+import android.nfc.tech.NfcA;
+import android.nfc.tech.NfcB;
 import android.os.Build;
 import android.os.Handler;
 import android.os.Looper;
@@ -109,14 +111,14 @@ public void reset() throws IOException {
  selectMF();
  }
 
- /* calculation based on https://code.google.com/p/ifdnfc/source/browse/src/atr.c */
+ /* generate the mapped ATR from 14443 data according to PC/SC part 3 section 3.1.3.2.3 */
  @Override
  public byte[] getATR() {
- // get historical bytes for 14443-A
+ // for 14443 Type A, use the historical bytes returned as part of the ATS
  byte[] historicalBytes = card.getHistoricalBytes();
  if (historicalBytes == null) {
- // get historical bytes for 14443-B
- historicalBytes = card.getHiLayerResponse();
+ // for 14443 Type B, use Application Data + Protocol Info + MBLI
+ historicalBytes = getTypeBHistoricalBytes();
  }
  if (historicalBytes == null) {
  historicalBytes = new byte[0];
@@ -177,4 +179,46 @@ public static NFCReader get(Tag tag, Activity activity) {
  }
  return nfcReader;
  }
-}
+
+ public byte[] getTypeBHistoricalBytes() {
+ NfcB nfcB = NfcB.get(card.getTag());
+ if (nfcB == null)
+ return null;
+
+ byte[] appData = nfcB.getApplicationData();
+ byte[] protocolInfo = nfcB.getProtocolInfo();
+ if (!(appData.length == 4 && protocolInfo.length == 3))
+ return null;
+
+ Byte mbli = translateToMbli(protocolInfo, nfcB.getMaxTransceiveLength());
+ if (mbli == null)
+ return null;
+
+ byte[] historicalBytes = new byte[8];
+ System.arraycopy(appData, 0, historicalBytes, 0, 4);
+ System.arraycopy(protocolInfo, 0, historicalBytes, 4, 3);
+ historicalBytes[7] = (byte)(mbli << 4);
+ return historicalBytes;
+ }
+
+ public static Byte translateToMbli(byte[] protocolInfo, int maxUnit) {
+ // retrieve maximum frame size from protocol info
+ int maxFrameSize = (protocolInfo[1] >> (byte)4) & 0xF;
+ if (maxFrameSize == 0)
+ return null;
+
+ // there's 3 to 5 bytes of overhead in a buffer.
+ int predictedMbl = maxUnit + 5; // (can be up to 2 bytes larger)
+
+ // buffer length must be maxFrameSize * {power of 2}.
+ int mbl = Integer.highestOneBit(predictedMbl / maxFrameSize) * maxFrameSize;
+ if (predictedMbl - mbl > 2)
+ return null;
+
+ // now that we know we have a valid MBL, calculate MBLI from it
+ int mbli = Integer.numberOfTrailingZeros(mbl / maxFrameSize) + 1;
+ if (mbli > 15)
+ return null;
+ return (byte)mbli;
+ }
+}