Check if security token keys match required once before signing/decryption

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/securitytoken/SecurityTokenHelper.java

@@ -131,13 +131,13 @@ public class SecurityTokenHelper {
     private boolean isSlotEmpty(KeyType keyType) throws IOException {
         // Note: special case: This should not happen, but happens with
         // https://github.com/FluffyKaon/OpenPGP-Card, thus for now assume true
-        if (getMasterKeyFingerprint(keyType.getIdx()) == null) return true;
+        if (getMasterKeyFingerprint(keyType) == null) return true;
 
         return keyMatchesFingerPrint(keyType, BLANK_FINGERPRINT);
     }
 
     public boolean keyMatchesFingerPrint(KeyType keyType, byte[] fingerprint) throws IOException {
-        return java.util.Arrays.equals(getMasterKeyFingerprint(keyType.getIdx()), fingerprint);
+        return java.util.Arrays.equals(getMasterKeyFingerprint(keyType), fingerprint);
     }
 
     /**
@@ -723,10 +723,10 @@ public class SecurityTokenHelper {
      * Return the fingerprint from application specific data stored on tag, or
      * null if it doesn't exist.
      *
-     * @param idx Index of the key to return the fingerprint from.
+     * @param keyType key.operatio type
      * @return The fingerprint of the requested key, or null if not found.
      */
-    public byte[] getMasterKeyFingerprint(int idx) throws IOException {
+    public byte[] getMasterKeyFingerprint(KeyType keyType) throws IOException {
         byte[] data = getFingerprints();
         if (data == null) {
             return null;
@@ -735,7 +735,7 @@ public class SecurityTokenHelper {
         // return the master key fingerprint
         ByteBuffer fpbuf = ByteBuffer.wrap(data);
         byte[] fp = new byte[20];
-        fpbuf.position(idx * 20);
+        fpbuf.position(keyType.getIdx() * 20);
         fpbuf.get(fp, 0, 20);
 
         return fp;

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

@@ -36,10 +36,12 @@ import org.sufficientlysecure.keychain.pgp.CanonicalizedSecretKey;
 import org.sufficientlysecure.keychain.pgp.CanonicalizedSecretKeyRing;
 import org.sufficientlysecure.keychain.provider.KeychainContract;
 import org.sufficientlysecure.keychain.provider.ProviderHelper;
+import org.sufficientlysecure.keychain.securitytoken.KeyType;
 import org.sufficientlysecure.keychain.service.PassphraseCacheService;
 import org.sufficientlysecure.keychain.service.input.CryptoInputParcel;
 import org.sufficientlysecure.keychain.service.input.RequiredInputParcel;
 import org.sufficientlysecure.keychain.ui.base.BaseSecurityTokenNfcActivity;
+import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils;
 import org.sufficientlysecure.keychain.ui.util.ThemeChanger;
 import org.sufficientlysecure.keychain.util.Log;
 import org.sufficientlysecure.keychain.util.OrientationUtils;
@@ -183,6 +185,13 @@ public class SecurityTokenOperationActivity extends BaseSecurityTokenNfcActivity
 
         switch (mRequiredInput.mType) {
             case SECURITY_TOKEN_DECRYPT: {
+                long tokenKeyId = KeyFormattingUtils.getKeyIdFromFingerprint(
+                        mSecurityTokenHelper.getMasterKeyFingerprint(KeyType.SIGN));
+
+                if (tokenKeyId != mRequiredInput.getMasterKeyId()) {
+                    throw new IOException(getString(R.string.error_wrong_security_token));
+                }
+
                 for (int i = 0; i < mRequiredInput.mInputData.length; i++) {
                     byte[] encryptedSessionKey = mRequiredInput.mInputData[i];
                     byte[] decryptedSessionKey = mSecurityTokenHelper.decryptSessionKey(encryptedSessionKey);
@@ -191,6 +200,13 @@ public class SecurityTokenOperationActivity extends BaseSecurityTokenNfcActivity
                 break;
             }
             case SECURITY_TOKEN_SIGN: {
+                long tokenKeyId = KeyFormattingUtils.getKeyIdFromFingerprint(
+                        mSecurityTokenHelper.getMasterKeyFingerprint(KeyType.SIGN));
+
+                if (tokenKeyId != mRequiredInput.getMasterKeyId()) {
+                    throw new IOException(getString(R.string.error_wrong_security_token));
+                }
+
                 mInputParcel.addSignatureTime(mRequiredInput.mSignatureTime);
 
                 for (int i = 0; i < mRequiredInput.mInputData.length; i++) {

OpenKeychain/src/main/res/values/strings.xml

@@ -380,6 +380,7 @@
     <string name="error_integrity_check_failed">"integrity check failed! Data has been modified!"</string>
     <string name="error_wrong_passphrase">"wrong password"</string>
     <string name="error_could_not_extract_private_key">"could not extract private key"</string>
+    <string name="error_wrong_security_token">"this security token doesn't contain required key"</string>
 
     <!-- errors without preceeding Error: -->
     <string name="error_jelly_bean_needed">"You need Android 4.1 to use Android's NFC Beam feature!"</string>