usb: respect automatic PPS feature flag

If the feature flag is set, don't do PPS negotiation. Closes #2219

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/usb/CcidDescription.java

@@ -36,6 +36,8 @@ abstract class CcidDescription {
 
     // dwFeatures Masks
     private static final int FEATURE_AUTOMATIC_VOLTAGE = 0x00008;
+    private static final int FEATURE_AUTOMATIC_PPS = 0x00080;
+
     private static final int FEATURE_EXCHANGE_LEVEL_TPDU = 0x10000;
     private static final int FEATURE_EXCHAGE_LEVEL_SHORT_APDU = 0x20000;
     private static final int FEATURE_EXCHAGE_LEVEL_EXTENDED_APDU = 0x40000;
@@ -130,6 +132,10 @@ abstract class CcidDescription {
         }
     }
 
+    boolean hasAutomaticPps() {
+        return hasFeature(FEATURE_AUTOMATIC_PPS);
+    }
+
     private boolean hasFeature(int feature) {
         return (getFeatures() & feature) != 0;
     }

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/usb/CcidTransceiver.java

@@ -258,6 +258,10 @@ public class CcidTransceiver {
         }
     }
 
+    public boolean hasAutomaticPps() {
+        return usbCcidDescription.hasAutomaticPps();
+    }
+
     /** Corresponds to 6.2.1 RDR_to_PC_DataBlock. */
     @AutoValue
     public abstract static class CcidDataBlock {

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/usb/tpdu/T1TpduProtocol.java

@@ -54,7 +54,10 @@ public class T1TpduProtocol implements CcidTransportProtocol {
         // TODO: set checksum from atr
         blockFactory = new T1TpduBlockFactory(BlockChecksumAlgorithm.LRC);
 
-        performPpsExchange();
+        boolean skipPpsExchange = ccidTransceiver.hasAutomaticPps();
+        if (!skipPpsExchange) {
+            performPpsExchange();
+        }
     }
 
     private void performPpsExchange() throws UsbTransportException {

OpenKeychain/src/test/java/org/sufficientlysecure/keychain/securitytoken/usb/CcidTransceiverTest.java

@@ -269,6 +269,14 @@ public class CcidTransceiverTest {
         assertArrayEquals(Hex.decode(responseData), ccidDataBlock.getData());
     }
 
+    @Test
+    public void testReturnsCorrectAutoPpsFlag() throws Exception {
+        CcidDescription description = CcidDescription.fromValues((byte) 0, (byte) 7, 3, 65722);
+        CcidTransceiver ccidTransceiver = new CcidTransceiver(usbConnection, usbBulkIn, usbBulkOut, description);
+
+        assertTrue(ccidTransceiver.hasAutomaticPps());
+    }
+
     private void verifyDialog() {
         assertTrue(expectReplies.isEmpty());
         assertFalse(expectRepliesVerify.isEmpty());