tls-psk: first steps

2017-05-29 23:12:54 +02:00
parent 6e8a768011
commit a55445f5bb
7 changed files with 733 additions and 2 deletions
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/network/KeyTransferClientInteractor.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/network/KeyTransferClientInteractor.java
@@ -0,0 +1,182 @@
+/*
+ * Copyright (C) 2017 Tobias Schülke
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.sufficientlysecure.keychain.network;
+
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.InetAddress;
+import java.net.NetworkInterface;
+import java.net.Socket;
+import java.net.SocketTimeoutException;
+import java.security.KeyManagementException;
+import java.security.NoSuchAlgorithmException;
+import java.util.Collections;
+import java.util.List;
+
+import android.net.PskKeyManager;
+import android.os.Build.VERSION_CODES;
+import android.os.Handler;
+import android.os.Looper;
+import android.support.annotation.RequiresApi;
+
+import javax.crypto.SecretKey;
+import javax.crypto.spec.SecretKeySpec;
+import javax.net.ssl.KeyManager;
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.SSLEngine;
+import javax.net.ssl.SSLServerSocket;
+import javax.net.ssl.SSLSocket;
+import javax.net.ssl.TrustManager;
+import org.sufficientlysecure.keychain.Constants;
+import org.sufficientlysecure.keychain.util.Log;
+
+
+@RequiresApi(api = VERSION_CODES.LOLLIPOP)
+public class KeyTransferClientInteractor {
+    private static final int SHOW_CONNECTION_DETAILS = 1;
+    private static final int CONNECTION_ESTABLISHED = 2;
+    public static final int CONNECTION_LOST = 3;
+
+
+    private Thread socketThread;
+    private KeyTransferClientCallback callback;
+    private Handler handler;
+    private SSLServerSocket serverSocket;
+
+
+    public void connectToServer(final String connectionDetails, KeyTransferClientCallback callback) {
+        this.callback = callback;
+
+        handler = new Handler(Looper.getMainLooper());
+        socketThread = new Thread() {
+            @Override
+            public void run() {
+                serverSocket = null;
+                Socket socket = null;
+                BufferedReader bufferedReader = null;
+                try {
+                    int port = 1336;
+
+                    PKM pskKeyManager = new PKM();
+                    SSLContext sslContext = null;
+                    sslContext = SSLContext.getInstance("TLS");
+                    sslContext.init(new KeyManager[] { pskKeyManager }, new TrustManager[0], null);
+                    socket = sslContext.getSocketFactory().createSocket(InetAddress.getByName(connectionDetails), port);
+
+                    invokeListener(CONNECTION_ESTABLISHED, socket.getInetAddress().toString());
+
+                    socket.setSoTimeout(500);
+                    bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
+
+                    while (!isInterrupted() && socket.isConnected()) {
+                        try {
+                            String line = bufferedReader.readLine();
+                            if (line == null) {
+                                break;
+                            }
+                            Log.d(Constants.TAG, "got line: " + line);
+                        } catch (SocketTimeoutException e) {
+                            // ignore
+                        }
+                    }
+                    Log.d(Constants.TAG, "disconnected");
+                    invokeListener(CONNECTION_LOST, null);
+                } catch (NoSuchAlgorithmException | KeyManagementException | IOException e) {
+                    Log.e(Constants.TAG, "error!", e);
+                } finally {
+                    try {
+                        if (bufferedReader != null) {
+                            bufferedReader.close();
+                        }
+                    } catch (IOException e) {
+                        // ignore
+                    }
+                    try {
+                        if (socket != null) {
+                            socket.close();
+                        }
+                    } catch (IOException e) {
+                        // ignore
+                    }
+                    try {
+                        if (serverSocket != null) {
+                            serverSocket.close();
+                        }
+                    } catch (IOException e) {
+                        // ignore
+                    }
+                }
+            }
+        };
+
+        socketThread.start();
+    }
+
+    public void closeConnection() {
+        if (socketThread != null) {
+            socketThread.interrupt();
+        }
+
+        socketThread = null;
+        callback = null;
+    }
+
+    private void invokeListener(final int method, final String arg) {
+        if (handler == null) {
+            return;
+        }
+
+        Runnable runnable = new Runnable() {
+            @Override
+            public void run() {
+                if (callback == null) {
+                    return;
+                }
+
+                switch (method) {
+                    case CONNECTION_ESTABLISHED:
+                        callback.onConnectionEstablished(arg);
+                        break;
+                    case CONNECTION_LOST:
+                        callback.onConnectionLost();
+                }
+            }
+        };
+
+        handler.post(runnable);
+    }
+
+    public interface KeyTransferClientCallback {
+        void onConnectionEstablished(String otherName);
+        void onConnectionLost();
+    }
+
+    private static class PKM extends PskKeyManager implements KeyManager {
+        @Override
+        public SecretKey getKey(String identityHint, String identity, Socket socket) {
+            return new SecretKeySpec("swag".getBytes(), "AES");
+        }
+
+        @Override
+        public SecretKey getKey(String identityHint, String identity, SSLEngine engine) {
+            return new SecretKeySpec("swag".getBytes(), "AES");
+        }
+    }
+}
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/network/KeyTransferServerInteractor.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/network/KeyTransferServerInteractor.java
@@ -0,0 +1,229 @@
+/*
+ * Copyright (C) 2017 Tobias Schülke
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.sufficientlysecure.keychain.network;
+
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.InetAddress;
+import java.net.NetworkInterface;
+import java.net.Socket;
+import java.net.SocketTimeoutException;
+import java.security.KeyManagementException;
+import java.security.NoSuchAlgorithmException;
+import java.util.Collections;
+import java.util.List;
+
+import android.net.PskKeyManager;
+import android.os.Build.VERSION_CODES;
+import android.os.Handler;
+import android.os.Looper;
+import android.support.annotation.RequiresApi;
+
+import javax.crypto.SecretKey;
+import javax.crypto.spec.SecretKeySpec;
+import javax.net.ssl.KeyManager;
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.SSLEngine;
+import javax.net.ssl.SSLServerSocket;
+import javax.net.ssl.TrustManager;
+import org.sufficientlysecure.keychain.Constants;
+import org.sufficientlysecure.keychain.util.Log;
+
+
+@RequiresApi(api = VERSION_CODES.LOLLIPOP)
+public class KeyTransferServerInteractor {
+    private static final int SHOW_CONNECTION_DETAILS = 1;
+    private static final int CONNECTION_ESTABLISHED = 2;
+    public static final int CONNECTION_LOST = 3;
+
+
+    private Thread socketThread;
+    private KeyTransferServerCallback callback;
+    private Handler handler;
+    private SSLServerSocket serverSocket;
+
+    public void startServer(KeyTransferServerCallback callback) {
+        this.callback = callback;
+
+        handler = new Handler(Looper.getMainLooper());
+        socketThread = new Thread() {
+            @Override
+            public void run() {
+                serverSocket = null;
+                Socket socket = null;
+                BufferedReader bufferedReader = null;
+                try {
+                    int port = 1336;
+
+                    PKM pskKeyManager = new PKM();
+                    SSLContext sslContext = SSLContext.getInstance("TLS");
+                    sslContext.init(new KeyManager[] { pskKeyManager }, new TrustManager[0], null);
+                    serverSocket = (SSLServerSocket) sslContext.getServerSocketFactory().createServerSocket(port);
+
+                    String qrCodeData = getIPAddress(true) + ":" + port + ":" + "swag";
+                    invokeListener(SHOW_CONNECTION_DETAILS, qrCodeData);
+
+                    socket = serverSocket.accept();
+                    invokeListener(CONNECTION_ESTABLISHED, socket.getInetAddress().toString());
+
+                    socket.setSoTimeout(500);
+                    bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
+
+                    while (!isInterrupted() && socket.isConnected()) {
+                        try {
+                            String line = bufferedReader.readLine();
+                            if (line == null) {
+                                break;
+                            }
+                            Log.d(Constants.TAG, "got line: " + line);
+                        } catch (SocketTimeoutException e) {
+                            // ignore
+                        }
+                    }
+                    Log.d(Constants.TAG, "disconnected");
+                    invokeListener(CONNECTION_LOST, null);
+                } catch (NoSuchAlgorithmException | KeyManagementException | IOException e) {
+                    Log.e(Constants.TAG, "error!", e);
+                } finally {
+                    try {
+                        if (bufferedReader != null) {
+                            bufferedReader.close();
+                        }
+                    } catch (IOException e) {
+                        // ignore
+                    }
+                    try {
+                        if (socket != null) {
+                            socket.close();
+                        }
+                    } catch (IOException e) {
+                        // ignore
+                    }
+                    try {
+                        if (serverSocket != null) {
+                            serverSocket.close();
+                        }
+                    } catch (IOException e) {
+                        // ignore
+                    }
+                }
+            }
+        };
+
+        socketThread.start();
+    }
+
+    public void stopServer() {
+        if (socketThread != null) {
+            socketThread.interrupt();
+        }
+
+        if (serverSocket != null) {
+            try {
+                serverSocket.close();
+            } catch (IOException e) {
+                // ignore
+            }
+        }
+
+        socketThread = null;
+        serverSocket = null;
+        callback = null;
+    }
+
+    private void invokeListener(final int method, final String arg) {
+        if (handler == null) {
+            return;
+        }
+
+        Runnable runnable = new Runnable() {
+            @Override
+            public void run() {
+                switch (method) {
+                    case SHOW_CONNECTION_DETAILS:
+                        callback.onServerStarted(arg);
+                        break;
+                    case CONNECTION_ESTABLISHED:
+                        callback.onConnectionEstablished(arg);
+                        break;
+                    case CONNECTION_LOST:
+                        callback.onConnectionLost();
+                }
+            }
+        };
+
+        handler.post(runnable);
+    }
+
+    public interface KeyTransferServerCallback {
+        void onServerStarted(String qrCodeData);
+        void onConnectionEstablished(String otherName);
+        void onConnectionLost();
+    }
+
+    /**
+     * from: http://stackoverflow.com/a/13007325
+     * <p>
+     * Get IP address from first non-localhost interface
+     *
+     * @param useIPv4 true=return ipv4, false=return ipv6
+     * @return address or empty string
+     */
+    private static String getIPAddress(boolean useIPv4) {
+        try {
+            List<NetworkInterface> interfaces = Collections.list(NetworkInterface.
+                    getNetworkInterfaces());
+            for (NetworkInterface intf : interfaces) {
+                List<InetAddress> addrs = Collections.list(intf.getInetAddresses());
+                for (InetAddress addr : addrs) {
+                    if (!addr.isLoopbackAddress()) {
+                        String sAddr = addr.getHostAddress();
+                        boolean isIPv4 = sAddr.indexOf(':') < 0;
+
+                        if (useIPv4) {
+                            if (isIPv4)
+                                return sAddr;
+                        } else {
+                            if (!isIPv4) {
+                                int delim = sAddr.indexOf('%'); // drop ip6 zone suffix
+                                return delim < 0 ? sAddr.toUpperCase() : sAddr.substring(0, delim).
+                                        toUpperCase();
+                            }
+                        }
+                    }
+                }
+            }
+        } catch (Exception ex) {
+        } // for now eat exceptions
+        return "";
+    }
+
+    private static class PKM extends PskKeyManager implements KeyManager {
+        @Override
+        public SecretKey getKey(String identityHint, String identity, Socket socket) {
+            return new SecretKeySpec("swag".getBytes(), "AES");
+        }
+
+        @Override
+        public SecretKey getKey(String identityHint, String identity, SSLEngine engine) {
+            return new SecretKeySpec("swag".getBytes(), "AES");
+        }
+    }
+}
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/MainActivity.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/MainActivity.java
@@ -41,6 +41,7 @@ import org.sufficientlysecure.keychain.R;
 import org.sufficientlysecure.keychain.operations.results.OperationResult;
 import org.sufficientlysecure.keychain.remote.ui.AppsListFragment;
 import org.sufficientlysecure.keychain.ui.base.BaseSecurityTokenActivity;
+import org.sufficientlysecure.keychain.ui.transfer.view.TransferFragment;
 import org.sufficientlysecure.keychain.util.FabContainer;
 import org.sufficientlysecure.keychain.util.Preferences;

@@ -50,8 +51,9 @@ public class MainActivity extends BaseSecurityTokenActivity implements FabContai
    static final int ID_ENCRYPT_DECRYPT = 2;
    static final int ID_APPS = 3;
    static final int ID_BACKUP = 4;
-    static final int ID_SETTINGS = 5;
-    static final int ID_HELP = 6;
+    static final int ID_TRANSFER = 5;
+    static final int ID_SETTINGS = 6;
+    static final int ID_HELP = 7;

    // both of these are used for instrumentation testing only
    public static final String EXTRA_SKIP_FIRST_TIME = "skip_first_time";
@@ -82,6 +84,8 @@ public class MainActivity extends BaseSecurityTokenActivity implements FabContai
                                .withIdentifier(ID_APPS).withSelectable(false),
                        new PrimaryDrawerItem().withName(R.string.nav_backup).withIcon(CommunityMaterial.Icon.cmd_backup_restore)
                                .withIdentifier(ID_BACKUP).withSelectable(false),
+                        new PrimaryDrawerItem().withName(R.string.nav_transfer).withIcon(CommunityMaterial.Icon.cmd_backup_restore)
+                                .withIdentifier(ID_TRANSFER).withSelectable(false),
                        new DividerDrawerItem(),
                        new PrimaryDrawerItem().withName(R.string.menu_preferences).withIcon(GoogleMaterial.Icon.gmd_settings).withIdentifier(ID_SETTINGS).withSelectable(false),
                        new PrimaryDrawerItem().withName(R.string.menu_help).withIcon(CommunityMaterial.Icon.cmd_help_circle).withIdentifier(ID_HELP).withSelectable(false)
@@ -105,6 +109,9 @@ public class MainActivity extends BaseSecurityTokenActivity implements FabContai
                                case ID_BACKUP:
                                    onBackupSelected();
                                    break;
+                                case ID_TRANSFER:
+                                    onTransferSelected();
+                                    break;
                                case ID_SETTINGS:
                                    intent = new Intent(MainActivity.this, SettingsActivity.class);
                                    break;
@@ -207,6 +214,13 @@ public class MainActivity extends BaseSecurityTokenActivity implements FabContai
        setFragment(frag, true);
    }

+    private void onTransferSelected() {
+        mToolbar.setTitle(R.string.nav_transfer);
+        mDrawer.setSelection(ID_TRANSFER, false);
+        Fragment frag = new TransferFragment();
+        setFragment(frag, true);
+    }
+
    @Override
    protected void onSaveInstanceState(Bundle outState) {
        // add the values which need to be saved from the drawer to the bundle
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/transfer/presenter/TransferPresenter.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/transfer/presenter/TransferPresenter.java
@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2017 Vincent Breitmoser <v.breitmoser@mugenguild.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.sufficientlysecure.keychain.ui.transfer.presenter;
+
+
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.net.Uri;
+import android.os.Build.VERSION_CODES;
+import android.support.annotation.RequiresApi;
+
+import org.sufficientlysecure.keychain.network.KeyTransferClientInteractor;
+import org.sufficientlysecure.keychain.network.KeyTransferClientInteractor.KeyTransferClientCallback;
+import org.sufficientlysecure.keychain.network.KeyTransferServerInteractor;
+import org.sufficientlysecure.keychain.network.KeyTransferServerInteractor.KeyTransferServerCallback;
+import org.sufficientlysecure.keychain.ui.util.QrCodeUtils;
+
+
+@RequiresApi(api = VERSION_CODES.LOLLIPOP)
+public class TransferPresenter implements KeyTransferServerCallback, KeyTransferClientCallback {
+    private final Context context;
+    private final TransferMvpView view;
+
+    private KeyTransferServerInteractor keyTransferServerInteractor;
+    private KeyTransferClientInteractor keyTransferClientInteractor;
+
+    public TransferPresenter(Context context, TransferMvpView view) {
+        this.context = context;
+        this.view = view;
+    }
+
+    public void onDestroy() {
+        clearConnections();
+    }
+
+    public void onClickScan() {
+        clearConnections();
+
+        keyTransferClientInteractor = new KeyTransferClientInteractor();
+        keyTransferClientInteractor.connectToServer("10.100.40.126", this);
+    }
+
+    private void clearConnections() {
+        if (keyTransferServerInteractor != null) {
+            keyTransferServerInteractor.stopServer();
+            keyTransferServerInteractor = null;
+        }
+        if (keyTransferClientInteractor != null) {
+            keyTransferClientInteractor.closeConnection();
+            keyTransferClientInteractor = null;
+        }
+    }
+
+    public void startServer() {
+        keyTransferServerInteractor = new KeyTransferServerInteractor();
+        keyTransferServerInteractor.startServer(this);
+    }
+
+    @Override
+    public void onServerStarted(String qrCodeData) {
+        Bitmap qrCodeBitmap = QrCodeUtils.getQRCodeBitmap(Uri.parse("pgp+transfer:" + qrCodeData), 0);
+        view.setQrImage(qrCodeBitmap);
+    }
+
+    @Override
+    public void onConnectionEstablished(String otherName) {
+        view.showConnectionEstablished(otherName);
+    }
+
+    @Override
+    public void onConnectionLost() {
+        view.showWaitingForConnection();
+        startServer();
+    }
+
+    public interface TransferMvpView {
+        void showConnectionEstablished(String hostname);
+        void showWaitingForConnection();
+
+        void setQrImage(Bitmap qrCode);
+    }
+}
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/transfer/view/TransferFragment.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/transfer/view/TransferFragment.java
@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2015 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.sufficientlysecure.keychain.ui.transfer.view;
+
+
+import android.graphics.Bitmap;
+import android.os.Build.VERSION_CODES;
+import android.os.Bundle;
+import android.support.annotation.Nullable;
+import android.support.annotation.RequiresApi;
+import android.support.v4.app.Fragment;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.View.OnClickListener;
+import android.view.ViewGroup;
+import android.view.ViewTreeObserver.OnGlobalLayoutListener;
+import android.widget.ImageView;
+import android.widget.TextView;
+import android.widget.ViewAnimator;
+
+import org.sufficientlysecure.keychain.R;
+import org.sufficientlysecure.keychain.ui.transfer.presenter.TransferPresenter;
+import org.sufficientlysecure.keychain.ui.transfer.presenter.TransferPresenter.TransferMvpView;
+
+
+@RequiresApi(api = VERSION_CODES.LOLLIPOP)
+public class TransferFragment extends Fragment implements TransferMvpView {
+    public static final int VIEW_WAITING = 0;
+    public static final int VIEW_CONNECTED = 1;
+
+
+    private ImageView vQrCodeImage;
+    private View vScanButton;
+    private TransferPresenter presenter;
+    private ViewAnimator vTransferAnimator;
+    private TextView vConnectionStatusText;
+
+
+    @Override
+    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
+        View view = inflater.inflate(R.layout.transfer_fragment, container, false);
+
+        vTransferAnimator = (ViewAnimator) view.findViewById(R.id.transfer_animator);
+
+        vConnectionStatusText = (TextView) view.findViewById(R.id.connection_status);
+
+        vQrCodeImage = (ImageView) view.findViewById(R.id.qr_code_image);
+        vScanButton = view.findViewById(R.id.button_scan);
+        vScanButton.setOnClickListener(new OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                if (presenter != null) {
+                    presenter.onClickScan();
+                }
+            }
+        });
+
+        return view;
+    }
+
+
+    @Override
+    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
+        super.onActivityCreated(savedInstanceState);
+
+        presenter = new TransferPresenter(getContext(), this);
+    }
+
+    @Override
+    public void onStart() {
+        super.onStart();
+
+        presenter.startServer();
+    }
+
+
+    @Override
+    public void onStop() {
+        super.onStop();
+
+        presenter.onDestroy();
+    }
+
+    @Override
+    public void showWaitingForConnection() {
+        vTransferAnimator.setDisplayedChild(VIEW_WAITING);
+    }
+
+    @Override
+    public void showConnectionEstablished(String hostname) {
+        vTransferAnimator.setDisplayedChild(VIEW_CONNECTED);
+        vConnectionStatusText.setText("Connected to: " + hostname);
+    }
+
+    @Override
+    public void setQrImage(final Bitmap qrCode) {
+        vQrCodeImage.getViewTreeObserver().addOnGlobalLayoutListener(
+                new OnGlobalLayoutListener() {
+                    @Override
+                    public void onGlobalLayout() {
+                        // create actual bitmap in display dimensions
+                        Bitmap scaled = Bitmap.createScaledBitmap(qrCode,
+                                vQrCodeImage.getWidth(), vQrCodeImage.getWidth(), false);
+                        vQrCodeImage.setImageBitmap(scaled);
+                    }
+                });
+        vQrCodeImage.requestLayout();
+    }
+}
--- a/OpenKeychain/src/main/res/layout/transfer_fragment.xml
+++ b/OpenKeychain/src/main/res/layout/transfer_fragment.xml
@@ -0,0 +1,84 @@
+<?xml version="1.0" encoding="utf-8"?>
+<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:custom="http://schemas.android.com/apk/res-auto">
+
+    <org.sufficientlysecure.keychain.ui.widget.ToolableViewAnimator
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:id="@+id/transfer_animator"
+        android:inAnimation="@anim/fade_in_delayed"
+        android:outAnimation="@anim/fade_out"
+        custom:initialView="01">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            android:paddingLeft="16dp"
+            android:paddingRight="16dp"
+            android:paddingTop="16dp">
+
+            <ImageView
+                android:layout_width="250dp"
+                android:layout_height="250dp"
+                android:layout_gravity="center_horizontal"
+                android:layout_margin="8dp"
+                android:id="@+id/qr_code_image"
+                tools:src="@drawable/ic_qrcode_white_24dp"
+                tools:tint="@color/md_black_1000"
+                />
+
+            <Button
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_gravity="center_horizontal"
+                android:layout_margin="8dp"
+                android:id="@+id/button_scan"
+                android:text="Scan"
+                android:drawableLeft="@drawable/ic_qrcode_white_24dp"
+                android:drawablePadding="8dp"
+                />
+
+            <TextView
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_gravity="center_horizontal"
+                android:layout_margin="8dp"
+                android:text="Scan with either device to establish a secure connection for device setup."
+                android:textAppearance="?android:attr/textAppearanceMedium" />
+
+        </LinearLayout>
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            android:paddingLeft="16dp"
+            android:paddingRight="16dp"
+            android:paddingTop="16dp">
+
+            <TextView
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_gravity="center_horizontal"
+                android:layout_margin="8dp"
+                android:id="@+id/connection_status"
+                android:text="Connected to "
+                android:textAppearance="?android:attr/textAppearanceMedium" />
+
+            <TextView
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_gravity="center_horizontal"
+                android:layout_margin="8dp"
+                android:text="Available Keys:"
+                android:textAppearance="?android:attr/textAppearanceMedium" />
+
+        </LinearLayout>
+
+    </org.sufficientlysecure.keychain.ui.widget.ToolableViewAnimator>
+
+</ScrollView>
--- a/OpenKeychain/src/main/res/values/strings.xml
+++ b/OpenKeychain/src/main/res/values/strings.xml
@@ -848,6 +848,7 @@
    <string name="drawer_close">"Close navigation drawer"</string>
    <string name="my_keys">"My Keys"</string>
    <string name="nav_backup">"Backup/Restore"</string>
+    <string name="nav_transfer">"Transfer"</string>

    <!-- hints -->
    <string name="encrypt_content_edit_text_hint">"Type text"</string>