Merge branch '2167-decode-qr-code-for-pairing-with-mailbox' into 'master'

Create initial MailboxPairViewModel that decodes QR code

Closes #2167

See merge request briar/briar!1544

bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/AndroidTorPluginFactory.java

@@ -3,6 +3,7 @@ package org.briarproject.bramble.plugin.tor;
 import android.app.Application;
 
 import org.briarproject.bramble.api.battery.BatteryManager;
+import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.network.NetworkManager;
@@ -60,6 +61,7 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 	private final File torDirectory;
 	private int torSocksPort;
 	private int torControlPort;
+	private final CryptoComponent crypto;
 
 	@Inject
 	AndroidTorPluginFactory(@IoExecutor Executor ioExecutor,
@@ -77,7 +79,8 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 			Clock clock,
 			@TorDirectory File torDirectory,
 			@TorSocksPort int torSocksPort,
-			@TorControlPort int torControlPort) {
+			@TorControlPort int torControlPort,
+			CryptoComponent crypto) {
 		this.ioExecutor = ioExecutor;
 		this.wakefulIoExecutor = wakefulIoExecutor;
 		this.app = app;
@@ -94,6 +97,7 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 		this.torDirectory = torDirectory;
 		this.torSocksPort = torSocksPort;
 		this.torControlPort = torControlPort;
+		this.crypto = crypto;
 	}
 
 	@Override
@@ -135,7 +139,8 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		TorRendezvousCrypto torRendezvousCrypto = new TorRendezvousCryptoImpl();
+		TorRendezvousCrypto torRendezvousCrypto =
+				new TorRendezvousCryptoImpl(crypto);
 		AndroidTorPlugin plugin = new AndroidTorPlugin(ioExecutor,
 				wakefulIoExecutor, app, networkManager, locationUtils,
 				torSocketFactory, clock, resourceProvider,

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/CryptoComponent.java

@@ -170,4 +170,11 @@ public interface CryptoComponent {
 	 * length. The line terminator is CRLF.
 	 */
 	String asciiArmour(byte[] b, int lineLength);
+
+	/**
+	 * Encode the onion/hidden service address given its public key. As
+	 * specified here: https://gitweb.torproject.org/torspec.git/tree/rend-spec-v3.txt?id=29245fd5#n2135
+	 */
+	String encodeOnionAddress(byte[] publicKey);
+
 }

bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoComponentImpl.java

@@ -7,6 +7,7 @@ import net.i2p.crypto.eddsa.KeyPairGenerator;
 import org.bouncycastle.crypto.CryptoException;
 import org.bouncycastle.crypto.Digest;
 import org.bouncycastle.crypto.digests.Blake2bDigest;
+import org.bouncycastle.crypto.digests.SHA3Digest;
 import org.briarproject.bramble.api.crypto.AgreementPrivateKey;
 import org.briarproject.bramble.api.crypto.AgreementPublicKey;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
@@ -21,11 +22,13 @@ import org.briarproject.bramble.api.crypto.SignaturePrivateKey;
 import org.briarproject.bramble.api.crypto.SignaturePublicKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.system.SecureRandomProvider;
+import org.briarproject.bramble.util.Base32;
 import org.briarproject.bramble.util.ByteUtils;
 import org.briarproject.bramble.util.StringUtils;
 import org.whispersystems.curve25519.Curve25519;
 import org.whispersystems.curve25519.Curve25519KeyPair;
 
+import java.nio.charset.Charset;
 import java.security.GeneralSecurityException;
 import java.security.NoSuchAlgorithmException;
 import java.security.Provider;
@@ -58,6 +61,8 @@ class CryptoComponentImpl implements CryptoComponent {
 	private static final int PBKDF_SALT_BYTES = 32; // 256 bits
 	private static final byte PBKDF_FORMAT_SCRYPT = 0;
 	private static final byte PBKDF_FORMAT_SCRYPT_STRENGTHENED = 1;
+	private static final byte ONION_HS_PROTOCOL_VERSION = 3;
+	private static final int ONION_CHECKSUM_BYTES = 2;
 
 	private final SecureRandom secureRandom;
 	private final PasswordBasedKdf passwordBasedKdf;
@@ -442,4 +447,21 @@ class CryptoComponentImpl implements CryptoComponent {
 	public String asciiArmour(byte[] b, int lineLength) {
 		return AsciiArmour.wrap(b, lineLength);
 	}
+
+	@Override
+	public String encodeOnionAddress(byte[] publicKey) {
+		Digest digest = new SHA3Digest(256);
+		byte[] label = ".onion checksum".getBytes(Charset.forName("US-ASCII"));
+		digest.update(label, 0, label.length);
+		digest.update(publicKey, 0, publicKey.length);
+		digest.update(ONION_HS_PROTOCOL_VERSION);
+		byte[] checksum = new byte[digest.getDigestSize()];
+		digest.doFinal(checksum, 0);
+		byte[] address = new byte[publicKey.length + ONION_CHECKSUM_BYTES + 1];
+		arraycopy(publicKey, 0, address, 0, publicKey.length);
+		arraycopy(checksum, 0, address, publicKey.length, ONION_CHECKSUM_BYTES);
+		address[address.length - 1] = ONION_HS_PROTOCOL_VERSION;
+		return Base32.encode(address).toLowerCase();
+	}
+
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/tor/TorRendezvousCryptoImpl.java

@@ -4,39 +4,26 @@ import net.i2p.crypto.eddsa.spec.EdDSANamedCurveSpec;
 import net.i2p.crypto.eddsa.spec.EdDSANamedCurveTable;
 import net.i2p.crypto.eddsa.spec.EdDSAPrivateKeySpec;
 
-import org.bouncycastle.crypto.Digest;
-import org.bouncycastle.crypto.digests.SHA3Digest;
 import org.bouncycastle.util.encoders.Base64;
-import org.briarproject.bramble.util.Base32;
+import org.briarproject.bramble.api.crypto.CryptoComponent;
 
 import java.nio.charset.Charset;
 
-import static java.lang.System.arraycopy;
-
-public class TorRendezvousCryptoImpl implements TorRendezvousCrypto {
+class TorRendezvousCryptoImpl implements TorRendezvousCrypto {
 
 	private static final EdDSANamedCurveSpec CURVE_SPEC =
 			EdDSANamedCurveTable.getByName("Ed25519");
 
-	private static final byte HS_PROTOCOL_VERSION = 3;
-	private static final int CHECKSUM_BYTES = 2;
+	private final CryptoComponent crypto;
+
+	TorRendezvousCryptoImpl(CryptoComponent crypto) {
+		this.crypto = crypto;
+	}
 
 	@Override
 	public String getOnionAddress(byte[] seed) {
 		EdDSAPrivateKeySpec spec = new EdDSAPrivateKeySpec(seed, CURVE_SPEC);
-		byte[] publicKey = spec.getA().toByteArray();
-		Digest digest = new SHA3Digest(256);
-		byte[] label = ".onion checksum".getBytes(Charset.forName("US-ASCII"));
-		digest.update(label, 0, label.length);
-		digest.update(publicKey, 0, publicKey.length);
-		digest.update(HS_PROTOCOL_VERSION);
-		byte[] checksum = new byte[digest.getDigestSize()];
-		digest.doFinal(checksum, 0);
-		byte[] address = new byte[publicKey.length + CHECKSUM_BYTES + 1];
-		arraycopy(publicKey, 0, address, 0, publicKey.length);
-		arraycopy(checksum, 0, address, publicKey.length, CHECKSUM_BYTES);
-		address[address.length - 1] = HS_PROTOCOL_VERSION;
-		return Base32.encode(address).toLowerCase();
+		return crypto.encodeOnionAddress(spec.getA().toByteArray());
 	}
 
 	@Override

bramble-java/src/main/java/org/briarproject/bramble/plugin/tor/UnixTorPluginFactory.java

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.plugin.tor;
 
 import org.briarproject.bramble.api.battery.BatteryManager;
+import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.network.NetworkManager;
@@ -58,6 +59,7 @@ public class UnixTorPluginFactory implements DuplexPluginFactory {
 	private final File torDirectory;
 	private int torSocksPort;
 	private int torControlPort;
+	private final CryptoComponent crypto;
 
 	@Inject
 	UnixTorPluginFactory(@IoExecutor Executor ioExecutor,
@@ -73,7 +75,8 @@ public class UnixTorPluginFactory implements DuplexPluginFactory {
 			Clock clock,
 			@TorDirectory File torDirectory,
 			@TorSocksPort int torSocksPort,
-			@TorControlPort int torControlPort) {
+			@TorControlPort int torControlPort,
+			CryptoComponent crypto) {
 		this.ioExecutor = ioExecutor;
 		this.wakefulIoExecutor = wakefulIoExecutor;
 		this.networkManager = networkManager;
@@ -88,6 +91,7 @@ public class UnixTorPluginFactory implements DuplexPluginFactory {
 		this.torDirectory = torDirectory;
 		this.torSocksPort = torSocksPort;
 		this.torControlPort = torControlPort;
+		this.crypto = crypto;
 	}
 
 	@Override
@@ -128,7 +132,8 @@ public class UnixTorPluginFactory implements DuplexPluginFactory {
 
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		TorRendezvousCrypto torRendezvousCrypto = new TorRendezvousCryptoImpl();
+		TorRendezvousCrypto torRendezvousCrypto =
+				new TorRendezvousCryptoImpl(crypto);
 		UnixTorPlugin plugin = new UnixTorPlugin(ioExecutor, wakefulIoExecutor,
 				networkManager, locationUtils, torSocketFactory, clock,
 				resourceProvider, circumventionProvider, batteryManager,

bramble-java/src/test/java/org/briarproject/bramble/plugin/tor/BridgeTest.java

@@ -2,6 +2,7 @@ package org.briarproject.bramble.plugin.tor;
 
 import org.briarproject.bramble.BrambleCoreIntegrationTestEagerSingletons;
 import org.briarproject.bramble.api.battery.BatteryManager;
+import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.network.NetworkManager;
@@ -88,6 +89,8 @@ public class BridgeTest extends BrambleTestCase {
 	BackoffFactory backoffFactory;
 	@Inject
 	Clock clock;
+	@Inject
+	CryptoComponent crypto;
 
 	private final File torDir = getTestDirectory();
 	private final String bridge;
@@ -142,7 +145,7 @@ public class BridgeTest extends BrambleTestCase {
 				networkManager, locationUtils, eventBus, torSocketFactory,
 				backoffFactory, resourceProvider, bridgeProvider,
 				batteryManager, clock, torDir, DEFAULT_SOCKS_PORT,
-				DEFAULT_CONTROL_PORT);
+				DEFAULT_CONTROL_PORT, crypto);
 	}
 
 	@After

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -43,6 +43,7 @@ import org.briarproject.briar.android.hotspot.HotspotModule;
 import org.briarproject.briar.android.introduction.IntroductionModule;
 import org.briarproject.briar.android.logging.LoggingModule;
 import org.briarproject.briar.android.login.LoginModule;
+import org.briarproject.briar.android.mailbox.MailboxModule;
 import org.briarproject.briar.android.navdrawer.NavDrawerModule;
 import org.briarproject.briar.android.privategroup.conversation.GroupConversationModule;
 import org.briarproject.briar.android.privategroup.list.GroupListModule;
@@ -103,6 +104,7 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		SharingModule.class,
 		HotspotModule.class,
 		TransferDataModule.class,
+		MailboxModule.class,
 })
 public class AppModule {
 

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactFragment.java

@@ -20,6 +20,8 @@ import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgre
 import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementWaiting;
 import org.briarproject.briar.android.contact.add.nearby.AddContactState.QrCodeScanned;
 import org.briarproject.briar.android.fragment.BaseFragment;
+import org.briarproject.briar.android.qrcode.CameraException;
+import org.briarproject.briar.android.qrcode.CameraView;
 import org.briarproject.briar.android.view.QrCodeView;
 
 import java.util.logging.Logger;

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactViewModel.java

@@ -53,7 +53,8 @@ import org.briarproject.briar.android.contact.add.nearby.AddContactState.Contact
 import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementListening;
 import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementStarted;
 import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementWaiting;
-import org.briarproject.briar.android.util.QrCodeUtils;
+import org.briarproject.briar.android.qrcode.QrCodeDecoder;
+import org.briarproject.briar.android.qrcode.QrCodeUtils;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 

briar-android/src/main/java/org/briarproject/briar/android/hotspot/HotspotManager.java

@@ -24,7 +24,7 @@ import org.briarproject.bramble.api.settings.SettingsManager;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.hotspot.HotspotState.NetworkConfig;
-import org.briarproject.briar.android.util.QrCodeUtils;
+import org.briarproject.briar.android.qrcode.QrCodeUtils;
 
 import java.security.SecureRandom;
 import java.util.concurrent.Executor;
@@ -52,7 +52,7 @@ import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.briar.android.util.QrCodeUtils.HOTSPOT_QRCODE_FACTOR;
+import static org.briarproject.briar.android.qrcode.QrCodeUtils.HOTSPOT_QRCODE_FACTOR;
 import static org.briarproject.briar.android.util.UiUtils.handleException;
 
 @MethodsNotNullByDefault

briar-android/src/main/java/org/briarproject/briar/android/hotspot/WebServerManager.java

@@ -8,7 +8,7 @@ import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.android.hotspot.HotspotState.WebsiteConfig;
-import org.briarproject.briar.android.util.QrCodeUtils;
+import org.briarproject.briar.android.qrcode.QrCodeUtils;
 
 import java.io.IOException;
 import java.net.InetAddress;
@@ -27,7 +27,7 @@ import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.NetworkUtils.getNetworkInterfaces;
 import static org.briarproject.briar.android.hotspot.WebServer.PORT;
-import static org.briarproject.briar.android.util.QrCodeUtils.HOTSPOT_QRCODE_FACTOR;
+import static org.briarproject.briar.android.qrcode.QrCodeUtils.HOTSPOT_QRCODE_FACTOR;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault

briar-android/src/main/java/org/briarproject/briar/android/mailbox/MailboxModule.java

@@ -0,0 +1,19 @@
+package org.briarproject.briar.android.mailbox;
+
+import org.briarproject.briar.android.viewmodel.ViewModelKey;
+
+import androidx.lifecycle.ViewModel;
+import dagger.Binds;
+import dagger.Module;
+import dagger.multibindings.IntoMap;
+
+@Module
+public interface MailboxModule {
+
+	@Binds
+	@IntoMap
+	@ViewModelKey(MailboxPairViewModel.class)
+	ViewModel bindMailboxViewModel(
+			MailboxPairViewModel mailboxPairViewModel);
+
+}

briar-android/src/main/java/org/briarproject/briar/android/mailbox/MailboxPairViewModel.java

@@ -0,0 +1,95 @@
+package org.briarproject.briar.android.mailbox;
+
+import android.app.Application;
+
+import com.google.zxing.Result;
+
+import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.util.StringUtils;
+import org.briarproject.briar.android.qrcode.QrCodeDecoder;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
+
+import java.nio.charset.Charset;
+import java.util.Arrays;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import androidx.annotation.Nullable;
+import androidx.annotation.UiThread;
+
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Logger.getLogger;
+
+@UiThread
+@NotNullByDefault
+class MailboxPairViewModel extends DbViewModel
+		implements QrCodeDecoder.ResultCallback {
+	private static final Logger LOG =
+			getLogger(MailboxPairViewModel.class.getName());
+
+	private static final int VERSION_REQUIRED = 32;
+
+	@SuppressWarnings("CharsetObjectCanBeUsed") // Requires minSdkVersion >= 19
+	private static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
+
+	private final CryptoComponent crypto;
+	private final QrCodeDecoder qrCodeDecoder;
+
+	@Nullable
+	private String onionAddress = null;
+	@Nullable
+	private String setupToken = null;
+
+	@Inject
+	MailboxPairViewModel(
+			Application app,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			@IoExecutor Executor ioExecutor,
+			CryptoComponent crypto) {
+		super(app, dbExecutor, lifecycleManager, db, androidExecutor);
+		this.crypto = crypto;
+		qrCodeDecoder = new QrCodeDecoder(androidExecutor, ioExecutor, this);
+	}
+
+	@Override
+	public void onQrCodeDecoded(Result result) {
+		LOG.info("Got result from decoder");
+		byte[] bytes = result.getText().getBytes(ISO_8859_1);
+
+		if (LOG.isLoggable(INFO))
+			LOG.info("QR code length in bytes: " + bytes.length);
+		if (bytes.length != 65) {
+			LOG.info("QR code has wrong length");
+			return;
+		}
+
+		if (LOG.isLoggable(INFO))
+			LOG.info("QR code version: " + bytes[0]);
+		if (bytes[0] != VERSION_REQUIRED) {
+			LOG.info("QR code has wrong version");
+			return;
+		}
+
+		byte[] onionPubKey = Arrays.copyOfRange(bytes, 1, 33);
+		onionAddress = crypto.encodeOnionAddress(onionPubKey);
+		setupToken = StringUtils.toHexString(Arrays.copyOfRange(bytes, 33, 65))
+				.toLowerCase();
+		LOG.info("QR code is valid");
+	}
+
+	QrCodeDecoder getQrCodeDecoder() {
+		return qrCodeDecoder;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/qrcode/CameraException.java

@@ -1,8 +1,8 @@
-package org.briarproject.briar.android.contact.add.nearby;
+package org.briarproject.briar.android.qrcode;
 
 import java.io.IOException;
 
-class CameraException extends IOException {
+public class CameraException extends IOException {
 
 	CameraException(String message) {
 		super(message);

briar-android/src/main/java/org/briarproject/briar/android/qrcode/CameraView.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.contact.add.nearby;
+package org.briarproject.briar.android.qrcode;
 
 import android.content.Context;
 import android.hardware.Camera;

briar-android/src/main/java/org/briarproject/briar/android/qrcode/PreviewConsumer.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.contact.add.nearby;
+package org.briarproject.briar.android.qrcode;
 
 import android.hardware.Camera;
 
@@ -7,7 +7,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import androidx.annotation.UiThread;
 
 @NotNullByDefault
-interface PreviewConsumer {
+public interface PreviewConsumer {
 
 	@UiThread
 	void start(Camera camera, int cameraIndex);

briar-android/src/main/java/org/briarproject/briar/android/qrcode/QrCodeDecoder.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.contact.add.nearby;
+package org.briarproject.briar.android.qrcode;
 
 import android.hardware.Camera;
 import android.hardware.Camera.CameraInfo;
@@ -32,7 +32,7 @@ import static java.util.logging.Logger.getLogger;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
+public class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 
 	private static final Logger LOG = getLogger(QrCodeDecoder.class.getName());
 
@@ -44,7 +44,7 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 	private Camera camera = null;
 	private int cameraIndex = 0;
 
-	QrCodeDecoder(AndroidExecutor androidExecutor,
+	public QrCodeDecoder(AndroidExecutor androidExecutor,
 			@IoExecutor Executor ioExecutor, ResultCallback callback) {
 		this.androidExecutor = androidExecutor;
 		this.ioExecutor = ioExecutor;
@@ -127,7 +127,7 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 	}
 
 	@NotNullByDefault
-	interface ResultCallback {
+	public interface ResultCallback {
 		@IoExecutor
 		void onQrCodeDecoded(Result result);
 	}

briar-android/src/main/java/org/briarproject/briar/android/qrcode/QrCodeUtils.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.util;
+package org.briarproject.briar.android.qrcode;
 
 import android.graphics.Bitmap;
 import android.util.DisplayMetrics;
@@ -23,11 +23,10 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
 public class QrCodeUtils {
+	public static final double HOTSPOT_QRCODE_FACTOR = 0.35;
 
 	private static final Logger LOG = getLogger(QrCodeUtils.class.getName());
 
-	public static final double HOTSPOT_QRCODE_FACTOR = 0.35;
-
 	@Nullable
 	public static Bitmap createQrCode(DisplayMetrics dm, String input) {
 		return createQrCode(Math.min(dm.widthPixels, dm.heightPixels), input);

briar-android/src/main/res/layout/fragment_keyagreement_qr.xml

@@ -5,7 +5,7 @@
 	android:layout_height="match_parent"
 	android:keepScreenOn="true">
 
-	<org.briarproject.briar.android.contact.add.nearby.CameraView
+	<org.briarproject.briar.android.qrcode.CameraView
 		android:id="@+id/camera_view"
 		android:layout_width="match_parent"
 		android:layout_height="match_parent" />