Fix crashes with Fluffys PGP applet

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpSecurityConstants.java

@@ -206,7 +206,7 @@ public class PgpSecurityConstants {
      * TODO: Ed25519
      * CITE: zooko's hash function table CITE: distinguishers on SHA-256
      */
-    public static final int DEFAULT_HASH_ALGORITHM = HashAlgorithmTags.SHA512;
+    public static final int DEFAULT_HASH_ALGORITHM = HashAlgorithmTags.SHA256;
 
     public interface OpenKeychainHashAlgorithmTags extends HashAlgorithmTags {
         int USE_DEFAULT = -1;

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/CreateKeyActivity.java

@@ -187,15 +187,17 @@ public class CreateKeyActivity extends BaseNfcActivity {
     }
 
     private boolean containsKeys(byte[] scannedFingerprints) {
+        if (scannedFingerprints == null) {
+            return false;
+        }
+
         // If all fingerprint bytes are 0, the card contains no keys.
-        boolean cardContainsKeys = false;
         for (byte b : scannedFingerprints) {
             if (b != 0) {
-                cardContainsKeys = true;
-                break;
+                return true;
             }
         }
-        return cardContainsKeys;
+        return false;
     }
 
     @Override

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/NfcOperationActivity.java

@@ -294,9 +294,11 @@ public class NfcOperationActivity extends BaseNfcActivity {
 
     private boolean shouldPutKey(byte[] fingerprint, int idx) throws IOException {
         byte[] cardFingerprint = nfcGetFingerprint(idx);
+
         // Slot is empty, or contains this key already. PUT KEY operation is safe
-        if (Arrays.equals(cardFingerprint, BLANK_FINGERPRINT) ||
-            Arrays.equals(cardFingerprint, fingerprint)) {
+        if (cardFingerprint == null ||
+                Arrays.equals(cardFingerprint, BLANK_FINGERPRINT) ||
+                Arrays.equals(cardFingerprint, fingerprint)) {
             return true;
         }
 

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/base/BaseNfcActivity.java

@@ -147,8 +147,6 @@ public abstract class BaseNfcActivity extends BaseActivity {
             protected Exception doInBackground(Void... params) {
                 try {
                     handleTagDiscoveredIntent(intent);
-                } catch (CardException e) {
-                    return e;
                 } catch (IOException e) {
                     return e;
                 }
@@ -406,6 +404,10 @@ public abstract class BaseNfcActivity extends BaseActivity {
 
         // Connect to the detected tag, setting a couple of settings
         mIsoDep = IsoDep.get(detectedTag);
+        if (mIsoDep == null) {
+            // TODO: better exception?
+            throw new IOException("Tag does not support ISO-DEP (ISO 14443-4)!");
+        }
         mIsoDep.setTimeout(TIMEOUT); // timeout is set to 100 seconds to avoid cancellation during calculation
         mIsoDep.connect();
 
@@ -496,6 +498,9 @@ public abstract class BaseNfcActivity extends BaseActivity {
      */
     public byte[] nfcGetFingerprint(int idx) throws IOException {
         byte[] data = nfcGetFingerprints();
+        if (data == null) {
+            return null;
+        }
 
         // return the master key fingerprint
         ByteBuffer fpbuf = ByteBuffer.wrap(data);
@@ -507,14 +512,11 @@ public abstract class BaseNfcActivity extends BaseActivity {
     }
 
     public byte[] nfcGetAid() throws IOException {
-
         String info = "00CA004F00";
         return mIsoDep.transceive(Hex.decode(info));
-
     }
 
     public String nfcGetUserId() throws IOException {
-
         String info = "00CA006500";
         return nfcGetHolderName(nfcCommunicate(info));
     }
@@ -952,14 +954,20 @@ public abstract class BaseNfcActivity extends BaseActivity {
     }
 
     public String nfcGetHolderName(String name) {
-        String slength;
-        int ilength;
-        name = name.substring(6);
-        slength = name.substring(0, 2);
-        ilength = Integer.parseInt(slength, 16) * 2;
-        name = name.substring(2, ilength + 2);
-        name = (new String(Hex.decode(name))).replace('<', ' ');
-        return (name);
+        try {
+            String slength;
+            int ilength;
+            name = name.substring(6);
+            slength = name.substring(0, 2);
+            ilength = Integer.parseInt(slength, 16) * 2;
+            name = name.substring(2, ilength + 2);
+            name = (new String(Hex.decode(name))).replace('<', ' ');
+            return name;
+        } catch (IndexOutOfBoundsException e) {
+            Log.e(Constants.TAG, "couldn't get holder name", e);
+            // try-catch for https://github.com/FluffyKaon/OpenPGP-Card
+            return "";
+        }
     }
 
     private String nfcGetDataField(String output) {