early support for detached signatures

k9mail/src/androidTest/java/com/fsck/k9/crypto/MessageDecryptVerifyerTest.java

@@ -19,13 +19,13 @@ import static junit.framework.Assert.assertSame;
 
 
 @RunWith(AndroidJUnit4.class)
-public class MessageDecryptorTest {
+public class MessageDecryptVerifyerTest {
 
     @Test
     public void findEncryptedPartsShouldReturnEmptyListForEmptyMessage() throws Exception {
         MimeMessage emptyMessage = new MimeMessage();
 
-        List<Part> encryptedParts = MessageDecryptor.findEncryptedParts(emptyMessage);
+        List<Part> encryptedParts = MessageDecryptVerifyer.findEncryptedParts(emptyMessage);
         assertEquals(0, encryptedParts.size());
     }
 
@@ -34,7 +34,7 @@ public class MessageDecryptorTest {
         MimeMessage message = new MimeMessage();
         message.setBody(new TextBody("message text"));
 
-        List<Part> encryptedParts = MessageDecryptor.findEncryptedParts(message);
+        List<Part> encryptedParts = MessageDecryptVerifyer.findEncryptedParts(message);
         assertEquals(0, encryptedParts.size());
     }
 
@@ -45,7 +45,7 @@ public class MessageDecryptorTest {
         mulitpartEncrypted.setSubType("encrypted");
         MimeMessageHelper.setBody(message, mulitpartEncrypted);
 
-        List<Part> encryptedParts = MessageDecryptor.findEncryptedParts(message);
+        List<Part> encryptedParts = MessageDecryptVerifyer.findEncryptedParts(message);
         assertEquals(1, encryptedParts.size());
         assertSame(message, encryptedParts.get(0));
     }
@@ -70,7 +70,7 @@ public class MessageDecryptorTest {
         MimeBodyPart bodyPartThree = new MimeBodyPart(mulitpartEncryptedThree);
         multipartMixed.addBodyPart(bodyPartThree);
 
-        List<Part> encryptedParts = MessageDecryptor.findEncryptedParts(message);
+        List<Part> encryptedParts = MessageDecryptVerifyer.findEncryptedParts(message);
         assertEquals(2, encryptedParts.size());
         assertSame(bodyPartOne, encryptedParts.get(0));
         assertSame(bodyPartThree, encryptedParts.get(1));

k9mail/src/main/java/com/fsck/k9/crypto/MessageDecryptVerifyer.java

@@ -0,0 +1,106 @@
+package com.fsck.k9.crypto;
+
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Stack;
+
+import com.fsck.k9.mail.Body;
+import com.fsck.k9.mail.BodyPart;
+import com.fsck.k9.mail.MessagingException;
+import com.fsck.k9.mail.Multipart;
+import com.fsck.k9.mail.Part;
+
+
+public class MessageDecryptVerifyer {
+    private static final String MULTIPART_ENCRYPTED = "multipart/encrypted";
+    private static final String MULTIPART_SIGNED = "multipart/signed";
+    private static final String PROTOCOL_PARAMETER = "protocol";
+    private static final String APPLICATION_PGP_ENCRYPTED = "application/pgp-encrypted";
+    private static final String APPLICATION_PGP_SIGNATURE = "application/pgp-signature";
+
+    public static List<Part> findEncryptedParts(Part startPart) {
+        List<Part> encryptedParts = new ArrayList<Part>();
+        Stack<Part> partsToCheck = new Stack<Part>();
+        partsToCheck.push(startPart);
+
+        while (!partsToCheck.isEmpty()) {
+            Part part = partsToCheck.pop();
+            String mimeType = part.getMimeType();
+            Body body = part.getBody();
+
+            if (MULTIPART_ENCRYPTED.equals(mimeType)) {
+                encryptedParts.add(part);
+            } else if (body instanceof Multipart) {
+                Multipart multipart = (Multipart) body;
+                for (int i = multipart.getCount() - 1; i >= 0; i--) {
+                    BodyPart bodyPart = multipart.getBodyPart(i);
+                    partsToCheck.push(bodyPart);
+                }
+            }
+        }
+
+        return encryptedParts;
+    }
+
+    public static List<Part> findSignedParts(Part startPart) {
+        List<Part> signedParts = new ArrayList<Part>();
+        Stack<Part> partsToCheck = new Stack<Part>();
+        partsToCheck.push(startPart);
+
+        while (!partsToCheck.isEmpty()) {
+            Part part = partsToCheck.pop();
+            String mimeType = part.getMimeType();
+            Body body = part.getBody();
+
+            if (MULTIPART_SIGNED.equals(mimeType)) {
+                signedParts.add(part);
+            } else if (body instanceof Multipart) {
+                Multipart multipart = (Multipart) body;
+                for (int i = multipart.getCount() - 1; i >= 0; i--) {
+                    BodyPart bodyPart = multipart.getBodyPart(i);
+                    partsToCheck.push(bodyPart);
+                }
+            }
+        }
+
+        return signedParts;
+    }
+
+    public static byte[] getSignatureData(Part part) throws IOException, MessagingException {
+
+        if (MULTIPART_SIGNED.equals(part.getMimeType())) {
+            Body body = part.getBody();
+            if (body instanceof Multipart) {
+                Multipart multi = (Multipart) body;
+                BodyPart signatureBody = multi.getBodyPart(1);
+                if (APPLICATION_PGP_SIGNATURE.equals(signatureBody.getMimeType())) {
+                    ByteArrayOutputStream bos = new ByteArrayOutputStream();
+                    signatureBody.getBody().writeTo(bos);
+                    return bos.toByteArray();
+                }
+            }
+        }
+
+        return null;
+    }
+
+    public static boolean isPgpMimePart(Part part) {
+        return isPgpMimeSignedPart(part) || isPgpMimeEncryptedPart(part);
+    }
+
+    public static boolean isPgpMimeSignedPart(Part part) {
+        return MULTIPART_SIGNED.equals(part.getMimeType());
+    }
+
+    public static boolean isPgpMimeEncryptedPart(Part part) {
+        //FIXME: Doesn't work right now because LocalMessage.getContentType() doesn't load headers from database
+//        String contentType = part.getContentType();
+//        String protocol = MimeUtility.getHeaderParameter(contentType, PROTOCOL_PARAMETER);
+//        return APPLICATION_PGP_ENCRYPTED.equals(protocol);
+        return MULTIPART_ENCRYPTED.equals(part.getMimeType());
+    }
+
+}

k9mail/src/main/java/com/fsck/k9/crypto/MessageDecryptor.java

@@ -1,51 +0,0 @@
-package com.fsck.k9.crypto;
-
-
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Stack;
-
-import com.fsck.k9.mail.Body;
-import com.fsck.k9.mail.BodyPart;
-import com.fsck.k9.mail.Multipart;
-import com.fsck.k9.mail.Part;
-import com.fsck.k9.mail.internet.MimeUtility;
-
-
-public class MessageDecryptor {
-    private static final String MULTIPART_ENCRYPTED = "multipart/encrypted";
-    private static final String PROTOCOL_PARAMETER = "protocol";
-    private static final String APPLICATION_PGP_ENCRYPTED = "application/pgp-encrypted";
-
-    public static List<Part> findEncryptedParts(Part startPart) {
-        List<Part> encryptedParts = new ArrayList<Part>();
-        Stack<Part> partsToCheck = new Stack<Part>();
-        partsToCheck.push(startPart);
-
-        while (!partsToCheck.isEmpty()) {
-            Part part = partsToCheck.pop();
-            String mimeType = part.getMimeType();
-            Body body = part.getBody();
-
-            if (MULTIPART_ENCRYPTED.equals(mimeType)) {
-                encryptedParts.add(part);
-            } else if (body instanceof Multipart) {
-                Multipart multipart = (Multipart) body;
-                for (int i = multipart.getCount() - 1; i >= 0; i--) {
-                    BodyPart bodyPart = multipart.getBodyPart(i);
-                    partsToCheck.push(bodyPart);
-                }
-            }
-        }
-
-        return encryptedParts;
-    }
-
-    public static boolean isPgpMimeEncryptedPart(Part part) {
-        //FIXME: Doesn't work right now because LocalMessage.getContentType() doesn't load headers from database
-//        String contentType = part.getContentType();
-//        String protocol = MimeUtility.getHeaderParameter(contentType, PROTOCOL_PARAMETER);
-//        return APPLICATION_PGP_ENCRYPTED.equals(protocol);
-        return true;
-    }
-}

k9mail/src/main/java/com/fsck/k9/mailstore/DecryptStreamParser.java

@@ -24,13 +24,11 @@ import org.apache.james.mime4j.parser.MimeStreamParser;
 import org.apache.james.mime4j.stream.BodyDescriptor;
 import org.apache.james.mime4j.stream.Field;
 import org.apache.james.mime4j.stream.MimeConfig;
-import org.openintents.openpgp.OpenPgpError;
-import org.openintents.openpgp.OpenPgpSignatureResult;
 
 
 public class DecryptStreamParser {
-    public static DecryptedBodyPart parse(InputStream inputStream) throws MessagingException, IOException {
+    public static OpenPgpResultBodyPart parse(InputStream inputStream) throws MessagingException, IOException {
-        DecryptedBodyPart decryptedRootPart = new DecryptedBodyPart();
+        OpenPgpResultBodyPart decryptedRootPart = new OpenPgpResultBodyPart(true);
 
         MimeConfig parserConfig  = new MimeConfig();
         parserConfig.setMaxHeaderLen(-1);
@@ -66,10 +64,10 @@ public class DecryptStreamParser {
 
 
     private static class PartBuilder  implements ContentHandler {
-        private final DecryptedBodyPart decryptedRootPart;
+        private final OpenPgpResultBodyPart decryptedRootPart;
         private final Stack<Object> stack = new Stack<Object>();
 
-        public PartBuilder(DecryptedBodyPart decryptedRootPart) throws MessagingException {
+        public PartBuilder(OpenPgpResultBodyPart decryptedRootPart) throws MessagingException {
             this.decryptedRootPart = decryptedRootPart;
         }
 
@@ -182,28 +180,4 @@ public class DecryptStreamParser {
         }
     }
 
-    public static class DecryptedBodyPart extends MimeBodyPart {
-        private OpenPgpSignatureResult signatureResult;
-        private OpenPgpError error;
-
-        public DecryptedBodyPart() throws MessagingException {
-            // Do nothing
-        }
-
-        public OpenPgpSignatureResult getSignatureResult() {
-            return signatureResult;
-        }
-
-        public void setSignatureResult(OpenPgpSignatureResult signatureResult) {
-            this.signatureResult = signatureResult;
-        }
-
-        public OpenPgpError getError() {
-            return error;
-        }
-
-        public void setError(OpenPgpError error) {
-            this.error = error;
-        }
-    }
 }

k9mail/src/main/java/com/fsck/k9/mailstore/LocalMessageExtractor.java

@@ -3,11 +3,9 @@ package com.fsck.k9.mailstore;
 import android.app.PendingIntent;
 import android.content.Context;
 import android.net.Uri;
-import android.util.Log;
 
-import com.fsck.k9.K9;
 import com.fsck.k9.R;
-import com.fsck.k9.crypto.MessageDecryptor;
+import com.fsck.k9.crypto.MessageDecryptVerifyer;
 import com.fsck.k9.mail.Address;
 import com.fsck.k9.mail.Body;
 import com.fsck.k9.mail.BodyPart;
@@ -20,7 +18,6 @@ import com.fsck.k9.mail.internet.MessageExtractor;
 import com.fsck.k9.mail.internet.MimeHeader;
 import com.fsck.k9.mail.internet.MimeUtility;
 import com.fsck.k9.mail.internet.Viewable;
-import com.fsck.k9.mailstore.DecryptStreamParser.DecryptedBodyPart;
 import com.fsck.k9.mailstore.MessageViewInfo.MessageViewContainer;
 import com.fsck.k9.provider.AttachmentProvider;
 import org.openintents.openpgp.OpenPgpError;
@@ -443,7 +440,7 @@ public class LocalMessageExtractor {
             // TODO fill from part
             OpenPgpSignatureResult pgpResult = getSignatureResultForPart(part);
             OpenPgpError pgpError = null;
-            boolean wasEncrypted = false;
+            boolean wasEncrypted = getPartWasEncrypted(part);
             PendingIntent pendingIntent = null;
 
             containers.add(new MessageViewContainer(
@@ -454,6 +451,10 @@ public class LocalMessageExtractor {
         return new MessageViewInfo(containers, message);
     }
 
+    private static boolean getPartWasEncrypted(Part part) {
+        return (part instanceof OpenPgpResultBodyPart) && ((OpenPgpResultBodyPart) part).wasEncrypted();
+    }
+
     public static List<Part> getCryptPieces(Part part) throws MessagingException {
         ArrayList<Part> parts = new ArrayList<Part>();
         if (!getCryptSubPieces(part, parts)) {
@@ -477,6 +478,9 @@ public class LocalMessageExtractor {
                     parts.add(part);
                     return true;
                 }
+            } else if (MessageDecryptVerifyer.isPgpMimeSignedPart(part)) {
+                parts.add(part);
+                return true;
             } else if (isPgpMimeDecryptedPart(part)) {
                 parts.add(multi.getBodyPart(2));
                 return true;
@@ -488,14 +492,21 @@ public class LocalMessageExtractor {
     public static boolean isPgpMimeDecryptedPart (Part part) {
         Body body = part.getBody();
         return (body instanceof Multipart)
-                && MessageDecryptor.isPgpMimeEncryptedPart(part)
+                && MessageDecryptVerifyer.isPgpMimeEncryptedPart(part)
-                && ((Multipart) part.getBody()).getBodyParts().size() == 3;
+                && ((Multipart) part.getBody()).getCount() == 3;
     }
 
     private static OpenPgpSignatureResult getSignatureResultForPart(Part part) {
-        if (part instanceof DecryptedBodyPart) {
+        if (part instanceof OpenPgpResultBodyPart) {
-            DecryptedBodyPart decryptedBodyPart = (DecryptedBodyPart) part;
+            OpenPgpResultBodyPart openPgpResultBodyPart = (OpenPgpResultBodyPart) part;
-            return decryptedBodyPart.getSignatureResult();
+            return openPgpResultBodyPart.getSignatureResult();
+        }
+        if (MessageDecryptVerifyer.isPgpMimeSignedPart(part)) {
+            Multipart multi = (Multipart) part.getBody();
+            if (multi.getCount() == 3 && multi.getBodyPart(2) instanceof OpenPgpResultBodyPart) {
+                OpenPgpResultBodyPart openPgpResultBodyPart = (OpenPgpResultBodyPart) multi.getBodyPart(2);
+                return openPgpResultBodyPart.getSignatureResult();
+            }
         }
 
         return NO_SIGNATURE_RESULT;

k9mail/src/main/java/com/fsck/k9/mailstore/OpenPgpResultBodyPart.java

@@ -0,0 +1,38 @@
+package com.fsck.k9.mailstore;
+
+
+import com.fsck.k9.mail.MessagingException;
+import com.fsck.k9.mail.internet.MimeBodyPart;
+import org.openintents.openpgp.OpenPgpError;
+import org.openintents.openpgp.OpenPgpSignatureResult;
+
+
+public class OpenPgpResultBodyPart extends MimeBodyPart {
+    private boolean wasEncrypted;
+    private OpenPgpSignatureResult signatureResult;
+    private OpenPgpError error;
+
+    public OpenPgpResultBodyPart(boolean wasEncrypted) throws MessagingException {
+        this.wasEncrypted = wasEncrypted;
+    }
+
+    public OpenPgpSignatureResult getSignatureResult() {
+        return signatureResult;
+    }
+
+    public void setSignatureResult(OpenPgpSignatureResult signatureResult) {
+        this.signatureResult = signatureResult;
+    }
+
+    public OpenPgpError getError() {
+        return error;
+    }
+
+    public void setError(OpenPgpError error) {
+        this.error = error;
+    }
+
+    public boolean wasEncrypted() {
+        return wasEncrypted;
+    }
+}

k9mail/src/main/java/com/fsck/k9/ui/messageview/MessageViewFragment.java

@@ -47,7 +47,7 @@ import com.fsck.k9.activity.MessageList;
 import com.fsck.k9.activity.MessageReference;
 import com.fsck.k9.controller.MessagingController;
 import com.fsck.k9.controller.MessagingListener;
-import com.fsck.k9.crypto.MessageDecryptor;
+import com.fsck.k9.crypto.MessageDecryptVerifyer;
 import com.fsck.k9.crypto.OpenPgpApiHelper;
 import com.fsck.k9.crypto.PgpData;
 import com.fsck.k9.fragment.ConfirmationDialogFragment;
@@ -64,7 +64,7 @@ import com.fsck.k9.mail.Multipart;
 import com.fsck.k9.mail.Part;
 import com.fsck.k9.mailstore.AttachmentViewInfo;
 import com.fsck.k9.mailstore.DecryptStreamParser;
-import com.fsck.k9.mailstore.DecryptStreamParser.DecryptedBodyPart;
+import com.fsck.k9.mailstore.OpenPgpResultBodyPart;
 import com.fsck.k9.mailstore.LocalMessage;
 import com.fsck.k9.mailstore.MessageViewInfo;
 import com.fsck.k9.ui.message.DecodeMessageLoader;
@@ -139,10 +139,10 @@ public class MessageViewFragment extends Fragment implements ConfirmationDialogF
     private LoaderCallbacks<MessageViewInfo> decodeMessageLoaderCallback = new DecodeMessageLoaderCallback();
     private MessageViewInfo messageViewInfo;
     private AttachmentViewInfo currentAttachmentViewInfo;
-    private Deque<Part> partsToDecrypt;
+    private Deque<Part> partsToDecryptOrVerify;
     private OpenPgpApi openPgpApi;
-    private Part currentlyDecryptingPart;
+    private Part currentlyDecrypringOrVerifyingPart;
-    private Intent currentDecryptingResult;
+    private Intent currentCryptoResult;
 
 
     @Override
@@ -257,38 +257,42 @@ public class MessageViewFragment extends Fragment implements ConfirmationDialogF
         if (message.isBodyMissing()) {
             startDownloadingMessageBody(message);
         } else {
-            decryptMessagePartsIfNecessary(message);
+            decryptOrVerifyMessagePartsIfNecessary(message);
         }
     }
 
-    private void decryptMessagePartsIfNecessary(LocalMessage message) {
+    private void decryptOrVerifyMessagePartsIfNecessary(LocalMessage message) {
-        List<Part> encryptedParts = MessageDecryptor.findEncryptedParts(message);
+        List<Part> encryptedParts = MessageDecryptVerifyer.findEncryptedParts(message);
-        if (!encryptedParts.isEmpty()) {
+        List<Part> signedParts = MessageDecryptVerifyer.findSignedParts(message);
-            partsToDecrypt = new ArrayDeque<Part>(encryptedParts);
+        if (!encryptedParts.isEmpty() || !signedParts.isEmpty()) {
-            decryptNextPartOrStartExtractingTextAndAttachments();
+            partsToDecryptOrVerify = new ArrayDeque<Part>();
+            partsToDecryptOrVerify.addAll(encryptedParts);
+            partsToDecryptOrVerify.addAll(signedParts);
+            decryptOrVerifyNextPartOrStartExtractingTextAndAttachments();
         } else {
             startExtractingTextAndAttachments(message);
         }
     }
 
-    private void decryptNextPartOrStartExtractingTextAndAttachments() {
+    private void decryptOrVerifyNextPartOrStartExtractingTextAndAttachments() {
-        if (partsToDecrypt.isEmpty()) {
+        if (!partsToDecryptOrVerify.isEmpty()) {
-            startExtractingTextAndAttachments(mMessage);
+
+            Part part = partsToDecryptOrVerify.peekFirst();
+            if (MessageDecryptVerifyer.isPgpMimePart(part)) {
+                startDecryptingOrVerifyingPart(part);
+            } else {
+                partsToDecryptOrVerify.removeFirst();
+                decryptOrVerifyNextPartOrStartExtractingTextAndAttachments();
+            }
+
             return;
         }
 
-        Part part = partsToDecrypt.peekFirst();
+        startExtractingTextAndAttachments(mMessage);
-        if (MessageDecryptor.isPgpMimeEncryptedPart(part)) {
-            startDecryptingPart(part);
-        } else {
-            // Note: We currently only support PGP/MIME multipart/encrypted parts
 
-            partsToDecrypt.removeFirst();
-            decryptNextPartOrStartExtractingTextAndAttachments();
-        }
     }
 
-    private void startDecryptingPart(Part part) {
+    private void startDecryptingOrVerifyingPart(Part part) {
         Multipart multipart = (Multipart) part.getBody();
         if (multipart == null) {
             throw new RuntimeException("Downloading missing parts before decryption isn't supported yet");
@@ -297,7 +301,7 @@ public class MessageViewFragment extends Fragment implements ConfirmationDialogF
         if (!isBoundToCryptoProviderService()) {
             connectToCryptoProviderService();
         } else {
-            decryptPart(part);
+            decryptOrVerifyPart(part);
         }
     }
 
@@ -313,7 +317,7 @@ public class MessageViewFragment extends Fragment implements ConfirmationDialogF
             public void onBound(IOpenPgpService service) {
                 openPgpApi = new OpenPgpApi(getContext(), service);
 
-                decryptNextPartOrStartExtractingTextAndAttachments();
+                decryptOrVerifyNextPartOrStartExtractingTextAndAttachments();
             }
 
             @Override
@@ -323,8 +327,8 @@ public class MessageViewFragment extends Fragment implements ConfirmationDialogF
         }).bindToService();
     }
 
-    private void decryptPart(Part part) {
+    private void decryptOrVerifyPart(Part part) {
-        currentlyDecryptingPart = part;
+        currentlyDecrypringOrVerifyingPart = part;
         decryptVerify(new Intent());
     }
 
@@ -336,24 +340,66 @@ public class MessageViewFragment extends Fragment implements ConfirmationDialogF
         intent.putExtra(OpenPgpApi.EXTRA_ACCOUNT_NAME, accountName);
 
         try {
-            final CountDownLatch latch = new CountDownLatch(1);
 
-            PipedInputStream pipedInputStream = getPipedInputStreamForEncryptedData();
+            PipedInputStream pipedInputStream;
-            PipedOutputStream decryptedOutputStream = getPipedOutputStreamForDecryptedData(latch);
+            PipedOutputStream decryptedOutputStream;
+            final CountDownLatch latch;
+
+            if (MessageDecryptVerifyer.isPgpMimeSignedPart(currentlyDecrypringOrVerifyingPart)) {
+                pipedInputStream = getPipedInputStreamForSignedData();
+
+                byte[] signatureData = MessageDecryptVerifyer.getSignatureData(currentlyDecrypringOrVerifyingPart);
+                intent.putExtra(OpenPgpApi.EXTRA_DETACHED_SIGNATURE, signatureData);
+                decryptedOutputStream = null;
+                latch = null;
+            } else {
+                pipedInputStream = getPipedInputStreamForEncryptedData();
+                latch = new CountDownLatch(1);
+                decryptedOutputStream = getPipedOutputStreamForDecryptedData(latch);
+            }
 
             openPgpApi.executeApiAsync(intent, pipedInputStream, decryptedOutputStream, new IOpenPgpCallback() {
                 @Override
                 public void onReturn(Intent result) {
+                    currentCryptoResult = result;
+
+                    if (latch != null) {
                         Log.d(K9.LOG_TAG, "on result!");
-                    currentDecryptingResult = result;
                         latch.countDown();
+                        return;
+                    }
+
+                    onCryptoConverge(null);
                 }
             });
         } catch (IOException e) {
             Log.e(K9.LOG_TAG, "IOException", e);
+        } catch (MessagingException e) {
+            Log.e(K9.LOG_TAG, "MessagingException", e);
         }
     }
 
+    private PipedInputStream getPipedInputStreamForSignedData() throws IOException {
+        PipedInputStream pipedInputStream = new PipedInputStream();
+
+        final PipedOutputStream out = new PipedOutputStream(pipedInputStream);
+        new Thread(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    Multipart multipartSignedMultipart = (Multipart) currentlyDecrypringOrVerifyingPart.getBody();
+                    BodyPart signatureBodyPart = multipartSignedMultipart.getBodyPart(0);
+                    Log.d(K9.LOG_TAG, "signed data type: " + signatureBodyPart.getMimeType());
+                    signatureBodyPart.writeTo(out);
+                } catch (Exception e) {
+                    Log.e(K9.LOG_TAG, "Exception while writing message to crypto provider", e);
+                }
+            }
+        }).start();
+
+        return pipedInputStream;
+    }
+
     private PipedInputStream getPipedInputStreamForEncryptedData() throws IOException {
         PipedInputStream pipedInputStream = new PipedInputStream();
 
@@ -362,7 +408,7 @@ public class MessageViewFragment extends Fragment implements ConfirmationDialogF
             @Override
             public void run() {
                 try {
-                    Multipart multipartEncryptedMultipart = (Multipart) currentlyDecryptingPart.getBody();
+                    Multipart multipartEncryptedMultipart = (Multipart) currentlyDecrypringOrVerifyingPart.getBody();
                     BodyPart encryptionPayloadPart = multipartEncryptedMultipart.getBodyPart(1);
                     Body encryptionPayloadBody = encryptionPayloadPart.getBody();
                     encryptionPayloadBody.writeTo(out);
@@ -378,10 +424,10 @@ public class MessageViewFragment extends Fragment implements ConfirmationDialogF
     private PipedOutputStream getPipedOutputStreamForDecryptedData(final CountDownLatch latch) throws IOException {
         PipedOutputStream decryptedOutputStream = new PipedOutputStream();
         final PipedInputStream decryptedInputStream = new PipedInputStream(decryptedOutputStream);
-        new AsyncTask<Void, Void, DecryptedBodyPart>() {
+        new AsyncTask<Void, Void, OpenPgpResultBodyPart>() {
             @Override
-            protected DecryptedBodyPart doInBackground(Void... params) {
+            protected OpenPgpResultBodyPart doInBackground(Void... params) {
-                DecryptedBodyPart decryptedPart = null;
+                OpenPgpResultBodyPart decryptedPart = null;
                 try {
                     decryptedPart = DecryptStreamParser.parse(decryptedInputStream);
 
@@ -396,21 +442,21 @@ public class MessageViewFragment extends Fragment implements ConfirmationDialogF
             }
 
             @Override
-            protected void onPostExecute(DecryptedBodyPart decryptedPart) {
+            protected void onPostExecute(OpenPgpResultBodyPart decryptedPart) {
-                onDecryptionConverge(decryptedPart);
+                onCryptoConverge(decryptedPart);
             }
         }.execute();
         return decryptedOutputStream;
     }
 
-    private void onDecryptionConverge (DecryptedBodyPart decryptedPart) {
+    private void onCryptoConverge(OpenPgpResultBodyPart openPgpResultBodyPart) {
         try {
-            if (currentDecryptingResult == null) {
+            if (currentCryptoResult == null) {
                 Log.e(K9.LOG_TAG, "Internal error: we should have a result here!");
                 return;
             }
 
-            int resultCode = currentDecryptingResult.getIntExtra(OpenPgpApi.RESULT_CODE, INVALID_OPENPGP_RESULT_CODE);
+            int resultCode = currentCryptoResult.getIntExtra(OpenPgpApi.RESULT_CODE, INVALID_OPENPGP_RESULT_CODE);
             if (K9.DEBUG) {
                 Log.d(K9.LOG_TAG, "OpenPGP API decryptVerify result code: " + resultCode);
             }
@@ -421,7 +467,7 @@ public class MessageViewFragment extends Fragment implements ConfirmationDialogF
                     break;
                 }
                 case OpenPgpApi.RESULT_CODE_USER_INTERACTION_REQUIRED: {
-                    PendingIntent pendingIntent = currentDecryptingResult.getParcelableExtra(OpenPgpApi.RESULT_INTENT);
+                    PendingIntent pendingIntent = currentCryptoResult.getParcelableExtra(OpenPgpApi.RESULT_INTENT);
                     if (pendingIntent == null) {
                         throw new AssertionError("Expecting PendingIntent on USER_INTERACTION_REQUIRED!");
                     }
@@ -435,62 +481,68 @@ public class MessageViewFragment extends Fragment implements ConfirmationDialogF
                     break;
                 }
                 case OpenPgpApi.RESULT_CODE_ERROR: {
-                    OpenPgpError error = currentDecryptingResult.getParcelableExtra(OpenPgpApi.RESULT_ERROR);
+                    OpenPgpError error = currentCryptoResult.getParcelableExtra(OpenPgpApi.RESULT_ERROR);
 
                     if (K9.DEBUG) {
                         Log.w(K9.LOG_TAG, "OpenPGP API error: " + error.getMessage());
                     }
 
-                    onDecryptionFailed(error);
+                    onCryptoFailed(error);
                     break;
                 }
                 case OpenPgpApi.RESULT_CODE_SUCCESS: {
+                    if (openPgpResultBodyPart == null) {
+                        openPgpResultBodyPart = new OpenPgpResultBodyPart(false);
+                    }
                     OpenPgpSignatureResult signatureResult =
-                            currentDecryptingResult.getParcelableExtra(OpenPgpApi.RESULT_SIGNATURE);
+                            currentCryptoResult.getParcelableExtra(OpenPgpApi.RESULT_SIGNATURE);
-                    decryptedPart.setSignatureResult(signatureResult);
+                    openPgpResultBodyPart.setSignatureResult(signatureResult);
 
-                    onDecryptionSuccess(decryptedPart);
+                    onCryptoSuccess(openPgpResultBodyPart);
                     break;
                 }
             }
+        } catch (MessagingException e) {
+            // catching the empty OpenPgpResultBodyPart constructor above - this can't actually happen
+            Log.e(K9.LOG_TAG, "This shouldn't happen", e);
         } finally {
-            currentDecryptingResult = null;
+            currentCryptoResult = null;
         }
     }
 
     public void handleCryptoResult(int resultCode, Intent data) {
         if (resultCode == Activity.RESULT_OK) {
-            decryptNextPartOrStartExtractingTextAndAttachments();
+            decryptOrVerifyNextPartOrStartExtractingTextAndAttachments();
         } else {
             //FIXME: don't pass null
-            onDecryptionFailed(null);
+            onCryptoFailed(null);
         }
     }
 
-    private void onDecryptionSuccess(DecryptedBodyPart decryptedPart) {
+    private void onCryptoSuccess(OpenPgpResultBodyPart decryptedPart) {
-        addDecryptedPartToMessage(decryptedPart);
+        addOpenPgpResultPartToMessage(decryptedPart);
-        onDecryptionFinished();
+        onCryptoFinished();
     }
 
-    private void addDecryptedPartToMessage(DecryptedBodyPart decryptedPart) {
+    private void addOpenPgpResultPartToMessage(OpenPgpResultBodyPart decryptedPart) {
-        Multipart multipart = (Multipart) currentlyDecryptingPart.getBody();
+        Multipart multipart = (Multipart) currentlyDecrypringOrVerifyingPart.getBody();
         multipart.addBodyPart(decryptedPart);
     }
 
-    private void onDecryptionFailed(OpenPgpError error) {
+    private void onCryptoFailed(OpenPgpError error) {
         try {
-            DecryptedBodyPart errorPart = new DecryptedBodyPart();
+            OpenPgpResultBodyPart errorPart = new OpenPgpResultBodyPart(false);
             errorPart.setError(error);
-            addDecryptedPartToMessage(errorPart);
+            addOpenPgpResultPartToMessage(errorPart);
         } catch (MessagingException e) {
             Log.e(K9.LOG_TAG, "This shouldn't happen", e);
         }
-        onDecryptionFinished();
+        onCryptoFinished();
     }
 
-    private void onDecryptionFinished() {
+    private void onCryptoFinished() {
-        partsToDecrypt.removeFirst();
+        partsToDecryptOrVerify.removeFirst();
-        decryptNextPartOrStartExtractingTextAndAttachments();
+        decryptOrVerifyNextPartOrStartExtractingTextAndAttachments();
     }
 
     private void onLoadMessageFromDatabaseFailed() {
@@ -527,7 +579,6 @@ public class MessageViewFragment extends Fragment implements ConfirmationDialogF
     }
 
     private void onDecodeMessageFinished(MessageViewInfo messageContainer) {
-        //TODO: handle decryption and signature verification
         this.messageViewInfo = messageContainer;
         showMessage(messageContainer);
     }