Merge branch '1696-keystore-crash' into 'master'

Show a dialog instead of crashing if a hardware-backed key can't be loaded

Closes #1696

See merge request briar/briar!1233

bramble-api/src/main/java/org/briarproject/bramble/api/account/AccountManager.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.api.account;
 
+import org.briarproject.bramble.api.crypto.DecryptionException;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -52,17 +53,19 @@ public interface AccountManager {
 	 * Loads the encrypted database key from disk and decrypts it with the
 	 * given password.
 	 *
-	 * @return true if the database key was successfully loaded and decrypted.
+	 * @throws DecryptionException If the database key could not be loaded and
+	 * decrypted.
 	 */
-	boolean signIn(String password);
+	void signIn(String password) throws DecryptionException;
 
 	/**
 	 * Loads the encrypted database key from disk, decrypts it with the old
 	 * password, encrypts it with the new password, and stores it on disk,
 	 * replacing the old key.
 	 *
-	 * @return true if the database key was successfully loaded, re-encrypted
-	 * and stored.
+	 * @throws DecryptionException If the database key could not be loaded and
+	 * decrypted.
 	 */
-	boolean changePassword(String oldPassword, String newPassword);
+	void changePassword(String oldPassword, String newPassword)
+			throws DecryptionException;
 }

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

@@ -142,16 +142,17 @@ public interface CryptoComponent {
 	/**
 	 * Decrypts and authenticates the given ciphertext that has been read from
 	 * storage. The encryption and authentication keys are derived from the
-	 * given password. Returns null if the ciphertext cannot be decrypted and
-	 * authenticated (for example, if the password is wrong).
+	 * given password.
 	 *
 	 * @param keyStrengthener Used to strengthen the password-based key. If
 	 * null, or if strengthening was not used when encrypting the ciphertext,
 	 * the password-based key will not be strengthened
+	 * @throws DecryptionException If the ciphertext cannot be decrypted and
+	 * authenticated (for example, if the password is wrong).
 	 */
-	@Nullable
 	byte[] decryptWithPassword(byte[] ciphertext, String password,
-			@Nullable KeyStrengthener keyStrengthener);
+			@Nullable KeyStrengthener keyStrengthener)
+			throws DecryptionException;
 
 	/**
 	 * Returns true if the given ciphertext was encrypted using a strengthened

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

@@ -0,0 +1,17 @@
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public class DecryptionException extends Exception {
+
+	private final DecryptionResult result;
+
+	public DecryptionException(DecryptionResult result) {
+		this.result = result;
+	}
+
+	public DecryptionResult getDecryptionResult() {
+		return result;
+	}
+}

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

@@ -0,0 +1,29 @@
+package org.briarproject.bramble.api.crypto;
+
+/**
+ * The result of a password-based decryption operation.
+ */
+public enum DecryptionResult {
+
+	/**
+	 * Decryption succeeded.
+	 */
+	SUCCESS,
+
+	/**
+	 * Decryption failed because the format of the ciphertext was invalid.
+	 */
+	INVALID_CIPHERTEXT,
+
+	/**
+	 * Decryption failed because the {@link KeyStrengthener} used for
+	 * encryption was not available for decryption.
+	 */
+	KEY_STRENGTHENER_ERROR,
+
+	/**
+	 * Decryption failed because the password used for decryption did not match
+	 * the password used for encryption.
+	 */
+	INVALID_PASSWORD
+}

bramble-core/src/main/java/org/briarproject/bramble/account/AccountManagerImpl.java

@@ -2,6 +2,7 @@ package org.briarproject.bramble.account;
 
 import org.briarproject.bramble.api.account.AccountManager;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.DecryptionException;
 import org.briarproject.bramble.api.crypto.KeyStrengthener;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DatabaseConfig;
@@ -17,6 +18,7 @@ import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.nio.charset.Charset;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
@@ -24,6 +26,7 @@ import javax.annotation.concurrent.GuardedBy;
 import javax.inject.Inject;
 
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_CIPHERTEXT;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.StringUtils.fromHexString;
 import static org.briarproject.bramble.util.StringUtils.toHexString;
@@ -95,7 +98,7 @@ class AccountManagerImpl implements AccountManager {
 		}
 		try {
 			BufferedReader reader = new BufferedReader(new InputStreamReader(
-					new FileInputStream(f), "UTF-8"));
+					new FileInputStream(f), Charset.forName("UTF-8")));
 			String key = reader.readLine();
 			reader.close();
 			return key;
@@ -147,7 +150,7 @@ class AccountManagerImpl implements AccountManager {
 	@GuardedBy("stateChangeLock")
 	private void writeDbKeyToFile(String key, File f) throws IOException {
 		FileOutputStream out = new FileOutputStream(f);
-		out.write(key.getBytes("UTF-8"));
+		out.write(key.getBytes(Charset.forName("UTF-8")));
 		out.flush();
 		out.close();
 	}
@@ -192,31 +195,24 @@ class AccountManagerImpl implements AccountManager {
 	}
 
 	@Override
-	public boolean signIn(String password) {
+	public void signIn(String password) throws DecryptionException {
 		synchronized (stateChangeLock) {
-			SecretKey key = loadAndDecryptDatabaseKey(password);
-			if (key == null) return false;
-			databaseKey = key;
-			return true;
+			databaseKey = loadAndDecryptDatabaseKey(password);
 		}
 	}
 
 	@GuardedBy("stateChangeLock")
-	@Nullable
-	private SecretKey loadAndDecryptDatabaseKey(String password) {
+	private SecretKey loadAndDecryptDatabaseKey(String password)
+			throws DecryptionException {
 		String hex = loadEncryptedDatabaseKey();
 		if (hex == null) {
 			LOG.warning("Failed to load encrypted database key");
-			return null;
+			throw new DecryptionException(INVALID_CIPHERTEXT);
 		}
 		byte[] ciphertext = fromHexString(hex);
 		KeyStrengthener keyStrengthener = databaseConfig.getKeyStrengthener();
 		byte[] plaintext = crypto.decryptWithPassword(ciphertext, password,
 				keyStrengthener);
-		if (plaintext == null) {
-			LOG.info("Failed to decrypt database key");
-			return null;
-		}
 		SecretKey key = new SecretKey(plaintext);
 		// If the DB key was encrypted with a weak key and a key strengthener
 		// is now available, re-encrypt the DB key with a strengthened key
@@ -229,10 +225,11 @@ class AccountManagerImpl implements AccountManager {
 	}
 
 	@Override
-	public boolean changePassword(String oldPassword, String newPassword) {
+	public void changePassword(String oldPassword, String newPassword)
+			throws DecryptionException {
 		synchronized (stateChangeLock) {
 			SecretKey key = loadAndDecryptDatabaseKey(oldPassword);
-			return key != null && encryptAndStoreDatabaseKey(key, newPassword);
+			encryptAndStoreDatabaseKey(key, newPassword);
 		}
 	}
 }

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

@@ -7,6 +7,7 @@ import net.i2p.crypto.eddsa.KeyPairGenerator;
 import org.briarproject.bramble.api.crypto.AgreementPrivateKey;
 import org.briarproject.bramble.api.crypto.AgreementPublicKey;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.DecryptionException;
 import org.briarproject.bramble.api.crypto.KeyPair;
 import org.briarproject.bramble.api.crypto.KeyParser;
 import org.briarproject.bramble.api.crypto.KeyStrengthener;
@@ -39,6 +40,9 @@ import static java.lang.System.arraycopy;
 import static java.util.logging.Level.INFO;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_AGREEMENT;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_SIGNATURE;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_CIPHERTEXT;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_PASSWORD;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.KEY_STRENGTHENER_ERROR;
 import static org.briarproject.bramble.util.ByteUtils.INT_32_BYTES;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.now;
@@ -359,16 +363,17 @@ class CryptoComponentImpl implements CryptoComponent {
 	}
 
 	@Override
-	@Nullable
 	public byte[] decryptWithPassword(byte[] input, String password,
-			@Nullable KeyStrengthener keyStrengthener) {
+			@Nullable KeyStrengthener keyStrengthener)
+			throws DecryptionException {
 		AuthenticatedCipher cipher = new XSalsa20Poly1305AuthenticatedCipher();
 		int macBytes = cipher.getMacBytes();
 		// The input contains the format version, salt, cost parameter, IV,
 		// ciphertext and MAC
 		if (input.length < 1 + PBKDF_SALT_BYTES + INT_32_BYTES
-				+ STORAGE_IV_BYTES + macBytes)
-			return null; // Invalid input
+				+ STORAGE_IV_BYTES + macBytes) {
+			throw new DecryptionException(INVALID_CIPHERTEXT);
+		}
 		int inputOff = 0;
 		// Format version
 		byte formatVersion = input[inputOff];
@@ -376,7 +381,7 @@ class CryptoComponentImpl implements CryptoComponent {
 		// Check whether we support this format version
 		if (formatVersion != PBKDF_FORMAT_SCRYPT &&
 				formatVersion != PBKDF_FORMAT_SCRYPT_STRENGTHENED) {
-			return null;
+			throw new DecryptionException(INVALID_CIPHERTEXT);
 		}
 		// Salt
 		byte[] salt = new byte[PBKDF_SALT_BYTES];
@@ -385,8 +390,9 @@ class CryptoComponentImpl implements CryptoComponent {
 		// Cost parameter
 		long cost = ByteUtils.readUint32(input, inputOff);
 		inputOff += INT_32_BYTES;
-		if (cost < 2 || cost > Integer.MAX_VALUE)
-			return null; // Invalid cost parameter
+		if (cost < 2 || cost > Integer.MAX_VALUE) {
+			throw new DecryptionException(INVALID_CIPHERTEXT);
+		}
 		// IV
 		byte[] iv = new byte[STORAGE_IV_BYTES];
 		arraycopy(input, inputOff, iv, 0, iv.length);
@@ -394,8 +400,10 @@ class CryptoComponentImpl implements CryptoComponent {
 		// Derive the decryption key from the password
 		SecretKey key = passwordBasedKdf.deriveKey(password, salt, (int) cost);
 		if (formatVersion == PBKDF_FORMAT_SCRYPT_STRENGTHENED) {
-			if (keyStrengthener == null || !keyStrengthener.isInitialised())
-				return null; // Can't derive the same strengthened key
+			if (keyStrengthener == null || !keyStrengthener.isInitialised()) {
+				// Can't derive the same strengthened key
+				throw new DecryptionException(KEY_STRENGTHENER_ERROR);
+			}
 			key = keyStrengthener.strengthenKey(key);
 		}
 		// Initialise the cipher
@@ -411,7 +419,7 @@ class CryptoComponentImpl implements CryptoComponent {
 			cipher.process(input, inputOff, inputLen, output, 0);
 			return output;
 		} catch (GeneralSecurityException e) {
-			return null; // Invalid ciphertext
+			throw new DecryptionException(INVALID_PASSWORD);
 		}
 	}
 

bramble-core/src/test/java/org/briarproject/bramble/account/AccountManagerImplTest.java

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.account;
 
 import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.DecryptionException;
 import org.briarproject.bramble.api.crypto.KeyStrengthener;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DatabaseConfig;
@@ -19,12 +20,15 @@ import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.nio.charset.Charset;
 
 import javax.annotation.Nullable;
 
 import static junit.framework.Assert.assertFalse;
 import static junit.framework.Assert.assertNull;
 import static junit.framework.Assert.assertTrue;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_CIPHERTEXT;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_PASSWORD;
 import static org.briarproject.bramble.test.TestUtils.deleteTestDirectory;
 import static org.briarproject.bramble.test.TestUtils.getIdentity;
 import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
@@ -35,6 +39,7 @@ import static org.briarproject.bramble.util.StringUtils.toHexString;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.fail;
 
 public class AccountManagerImplTest extends BrambleMockTestCase {
 
@@ -83,8 +88,13 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 	}
 
 	@Test
-	public void testSignInReturnsFalseIfDbKeyCannotBeLoaded() {
-		assertFalse(accountManager.signIn(password));
+	public void testSignInThrowsExceptionIfDbKeyCannotBeLoaded() {
+		try {
+			accountManager.signIn(password);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(INVALID_CIPHERTEXT, expected.getDecryptionResult());
+		}
 		assertFalse(accountManager.hasDatabaseKey());
 
 		assertFalse(keyFile.exists());
@@ -92,11 +102,11 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 	}
 
 	@Test
-	public void testSignInReturnsFalseIfPasswordIsWrong() throws Exception {
+	public void testSignInThrowsExceptionIfPasswordIsWrong() throws Exception {
 		context.checking(new Expectations() {{
 			oneOf(crypto).decryptWithPassword(encryptedKey, password,
 					keyStrengthener);
-			will(returnValue(null));
+			will(throwException(new DecryptionException(INVALID_PASSWORD)));
 		}});
 
 		storeDatabaseKey(keyFile, encryptedKeyHex);
@@ -105,7 +115,12 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
 
-		assertFalse(accountManager.signIn(password));
+		try {
+			accountManager.signIn(password);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(INVALID_PASSWORD, expected.getDecryptionResult());
+		}
 		assertFalse(accountManager.hasDatabaseKey());
 
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
@@ -128,7 +143,7 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
 
-		assertTrue(accountManager.signIn(password));
+		accountManager.signIn(password);
 		assertTrue(accountManager.hasDatabaseKey());
 		SecretKey decrypted = accountManager.getDatabaseKey();
 		assertNotNull(decrypted);
@@ -157,7 +172,7 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
 
-		assertTrue(accountManager.signIn(password));
+		accountManager.signIn(password);
 		assertTrue(accountManager.hasDatabaseKey());
 		SecretKey decrypted = accountManager.getDatabaseKey();
 		assertNotNull(decrypted);
@@ -266,26 +281,36 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 	}
 
 	@Test
-	public void testChangePasswordReturnsFalseIfDbKeyCannotBeLoaded() {
-		assertFalse(accountManager.changePassword(password, newPassword));
+	public void testChangePasswordThrowsExceptionIfDbKeyCannotBeLoaded() {
+		try {
+			accountManager.changePassword(password, newPassword);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(INVALID_CIPHERTEXT, expected.getDecryptionResult());
+		}
 
 		assertFalse(keyFile.exists());
 		assertFalse(keyBackupFile.exists());
 	}
 
 	@Test
-	public void testChangePasswordReturnsFalseIfPasswordIsWrong()
+	public void testChangePasswordThrowsExceptionIfPasswordIsWrong()
 			throws Exception {
 		context.checking(new Expectations() {{
 			oneOf(crypto).decryptWithPassword(encryptedKey, password,
 					keyStrengthener);
-			will(returnValue(null));
+			will(throwException(new DecryptionException(INVALID_PASSWORD)));
 		}});
 
 		storeDatabaseKey(keyFile, encryptedKeyHex);
 		storeDatabaseKey(keyBackupFile, encryptedKeyHex);
 
-		assertFalse(accountManager.changePassword(password, newPassword));
+		try {
+			accountManager.changePassword(password, newPassword);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(INVALID_PASSWORD, expected.getDecryptionResult());
+		}
 
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
@@ -308,7 +333,7 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 		storeDatabaseKey(keyFile, encryptedKeyHex);
 		storeDatabaseKey(keyBackupFile, encryptedKeyHex);
 
-		assertTrue(accountManager.changePassword(password, newPassword));
+		accountManager.changePassword(password, newPassword);
 
 		assertEquals(newEncryptedKeyHex, loadDatabaseKey(keyFile));
 		assertEquals(newEncryptedKeyHex, loadDatabaseKey(keyBackupFile));
@@ -317,7 +342,7 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 	private void storeDatabaseKey(File f, String hex) throws IOException {
 		f.getParentFile().mkdirs();
 		FileOutputStream out = new FileOutputStream(f);
-		out.write(hex.getBytes("UTF-8"));
+		out.write(hex.getBytes(Charset.forName("UTF-8")));
 		out.flush();
 		out.close();
 	}
@@ -325,7 +350,7 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 	@Nullable
 	private String loadDatabaseKey(File f) throws IOException {
 		BufferedReader reader = new BufferedReader(new InputStreamReader(
-				new FileInputStream(f), "UTF-8"));
+				new FileInputStream(f), Charset.forName("UTF-8")));
 		String hex = reader.readLine();
 		reader.close();
 		return hex;

bramble-core/src/test/java/org/briarproject/bramble/crypto/PasswordBasedEncryptionTest.java

@@ -1,25 +1,35 @@
 package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.api.crypto.DecryptionException;
+import org.briarproject.bramble.api.crypto.KeyStrengthener;
+import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.system.SystemClock;
-import org.briarproject.bramble.test.BrambleTestCase;
+import org.briarproject.bramble.test.BrambleMockTestCase;
 import org.briarproject.bramble.test.TestSecureRandomProvider;
-import org.briarproject.bramble.test.TestUtils;
+import org.jmock.Expectations;
 import org.junit.Test;
 
-import java.util.Random;
-
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_CIPHERTEXT;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_PASSWORD;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.KEY_STRENGTHENER_ERROR;
+import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
+import static org.briarproject.bramble.test.TestUtils.getSecretKey;
 import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
 
-public class PasswordBasedEncryptionTest extends BrambleTestCase {
+public class PasswordBasedEncryptionTest extends BrambleMockTestCase {
+
+	private final KeyStrengthener keyStrengthener =
+			context.mock(KeyStrengthener.class);
 
 	private final CryptoComponentImpl crypto =
 			new CryptoComponentImpl(new TestSecureRandomProvider(),
 					new ScryptKdf(new SystemClock()));
 
 	@Test
-	public void testEncryptionAndDecryption() {
-		byte[] input = TestUtils.getRandomBytes(1234);
+	public void testEncryptionAndDecryption() throws Exception {
+		byte[] input = getRandomBytes(1234);
 		String password = "password";
 		byte[] ciphertext = crypto.encryptWithPassword(input, password, null);
 		byte[] output = crypto.decryptWithPassword(ciphertext, password, null);
@@ -27,14 +37,80 @@ public class PasswordBasedEncryptionTest extends BrambleTestCase {
 	}
 
 	@Test
-	public void testInvalidCiphertextReturnsNull() {
-		byte[] input = TestUtils.getRandomBytes(1234);
+	public void testInvalidFormatVersionThrowsException() {
+		byte[] input = getRandomBytes(1234);
 		String password = "password";
 		byte[] ciphertext = crypto.encryptWithPassword(input, password, null);
-		// Modify the ciphertext
-		int position = new Random().nextInt(ciphertext.length);
-		ciphertext[position] = (byte) (ciphertext[position] ^ 0xFF);
-		byte[] output = crypto.decryptWithPassword(ciphertext, password, null);
-		assertNull(output);
+
+		// Modify the format version
+		ciphertext[0] ^= (byte) 0xFF;
+		try {
+			crypto.decryptWithPassword(ciphertext, password, null);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(INVALID_CIPHERTEXT, expected.getDecryptionResult());
+		}
+	}
+
+	@Test
+	public void testInvalidPasswordThrowsException() {
+		byte[] input = getRandomBytes(1234);
+		byte[] ciphertext = crypto.encryptWithPassword(input, "password", null);
+
+		// Try to decrypt with the wrong password
+		try {
+			crypto.decryptWithPassword(ciphertext, "wrong", null);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(INVALID_PASSWORD, expected.getDecryptionResult());
+		}
+	}
+
+	@Test
+	public void testMissingKeyStrengthenerThrowsException() {
+		SecretKey strengthened = getSecretKey();
+		context.checking(new Expectations() {{
+			oneOf(keyStrengthener).strengthenKey(with(any(SecretKey.class)));
+			will(returnValue(strengthened));
+		}});
+
+		// Use the key strengthener during encryption
+		byte[] input = getRandomBytes(1234);
+		String password = "password";
+		byte[] ciphertext =
+				crypto.encryptWithPassword(input, password, keyStrengthener);
+
+		// The key strengthener is missing during decryption
+		try {
+			crypto.decryptWithPassword(ciphertext, password, null);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(KEY_STRENGTHENER_ERROR, expected.getDecryptionResult());
+		}
+	}
+
+	@Test
+	public void testKeyStrengthenerFailureThrowsException() {
+		SecretKey strengthened = getSecretKey();
+		context.checking(new Expectations() {{
+			oneOf(keyStrengthener).strengthenKey(with(any(SecretKey.class)));
+			will(returnValue(strengthened));
+			oneOf(keyStrengthener).isInitialised();
+			will(returnValue(false));
+		}});
+
+		// Use the key strengthener during encryption
+		byte[] input = getRandomBytes(1234);
+		String password = "password";
+		byte[] ciphertext =
+				crypto.encryptWithPassword(input, password, keyStrengthener);
+
+		// The key strengthener fails during decryption
+		try {
+			crypto.decryptWithPassword(ciphertext, password, keyStrengthener);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(KEY_STRENGTHENER_ERROR, expected.getDecryptionResult());
+		}
 	}
 }

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

@@ -28,7 +28,9 @@ import static android.security.keystore.KeyProperties.PURPOSE_SIGN;
 import static java.util.Arrays.asList;
 import static java.util.Collections.singletonList;
 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.bramble.util.LogUtils.logException;
 
 @RequiresApi(23)
 @NotNullByDefault
@@ -79,7 +81,10 @@ class AndroidKeyStrengthener implements KeyStrengthener {
 				return true;
 			}
 			return false;
-		} catch (GeneralSecurityException | IOException e) {
+		} catch (GeneralSecurityException e) {
+			logException(LOG, WARNING, e);
+			return false;
+		} catch (IOException e) {
 			throw new RuntimeException(e);
 		}
 	}

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

@@ -36,6 +36,7 @@ import org.briarproject.bramble.util.AndroidUtils;
 import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.android.account.LockManagerImpl;
 import org.briarproject.briar.android.keyagreement.ContactExchangeModule;
+import org.briarproject.briar.android.login.LoginModule;
 import org.briarproject.briar.android.viewmodel.ViewModelModule;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.android.DozeWatchdog;
@@ -64,7 +65,11 @@ import static org.briarproject.bramble.api.reporting.ReportingConstants.DEV_ONIO
 import static org.briarproject.bramble.api.reporting.ReportingConstants.DEV_PUBLIC_KEY_HEX;
 import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 
-@Module(includes = {ContactExchangeModule.class, ViewModelModule.class})
+@Module(includes = {
+		ContactExchangeModule.class,
+		LoginModule.class,
+		ViewModelModule.class
+})
 public class AppModule {
 
 	static class EagerSingletons {

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityModule.java

@@ -8,8 +8,6 @@ import org.briarproject.briar.android.controller.BriarController;
 import org.briarproject.briar.android.controller.BriarControllerImpl;
 import org.briarproject.briar.android.controller.DbController;
 import org.briarproject.briar.android.controller.DbControllerImpl;
-import org.briarproject.briar.android.login.ChangePasswordController;
-import org.briarproject.briar.android.login.ChangePasswordControllerImpl;
 import org.briarproject.briar.android.navdrawer.NavDrawerController;
 import org.briarproject.briar.android.navdrawer.NavDrawerControllerImpl;
 
@@ -46,13 +44,6 @@ public class ActivityModule {
 		return setupController;
 	}
 
-	@ActivityScope
-	@Provides
-	ChangePasswordController providePasswordController(
-			ChangePasswordControllerImpl passwordController) {
-		return passwordController;
-	}
-
 	@ActivityScope
 	@Provides
 	protected BriarController provideBriarController(
@@ -80,5 +71,4 @@ public class ActivityModule {
 	BriarServiceConnection provideBriarServiceConnection() {
 		return new BriarServiceConnection();
 	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/login/ChangePasswordActivity.java

@@ -15,27 +15,33 @@ import android.widget.Toast;
 
 import com.google.android.material.textfield.TextInputLayout;
 
+import org.briarproject.bramble.api.crypto.DecryptionResult;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
-import org.briarproject.briar.android.controller.handler.UiResultHandler;
-import org.briarproject.briar.android.util.UiUtils;
 
 import javax.inject.Inject;
 
-import androidx.annotation.NonNull;
+import androidx.annotation.VisibleForTesting;
+import androidx.lifecycle.ViewModelProvider;
+import androidx.lifecycle.ViewModelProviders;
 
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
+import static android.widget.Toast.LENGTH_LONG;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.KEY_STRENGTHENER_ERROR;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.SUCCESS;
 import static org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.QUITE_WEAK;
+import static org.briarproject.briar.android.login.LoginUtils.createKeyStrengthenerErrorDialog;
 import static org.briarproject.briar.android.util.UiUtils.hideSoftKeyboard;
+import static org.briarproject.briar.android.util.UiUtils.setError;
 import static org.briarproject.briar.android.util.UiUtils.showSoftKeyboard;
 
 public class ChangePasswordActivity extends BriarActivity
 		implements OnClickListener, OnEditorActionListener {
 
 	@Inject
-	protected ChangePasswordController passwordController;
+	ViewModelProvider.Factory viewModelFactory;
 
 	private TextInputLayout currentPasswordEntryWrapper;
 	private TextInputLayout newPasswordEntryWrapper;
@@ -47,11 +53,17 @@ public class ChangePasswordActivity extends BriarActivity
 	private Button changePasswordButton;
 	private ProgressBar progress;
 
+	@VisibleForTesting
+	ChangePasswordViewModel viewModel;
+
 	@Override
 	public void onCreate(Bundle state) {
 		super.onCreate(state);
 		setContentView(R.layout.activity_change_password);
 
+		viewModel = ViewModelProviders.of(this, viewModelFactory)
+				.get(ChangePasswordViewModel.class);
+
 		currentPasswordEntryWrapper =
 				findViewById(R.id.current_password_entry_wrapper);
 		newPasswordEntryWrapper = findViewById(R.id.new_password_entry_wrapper);
@@ -102,13 +114,12 @@ public class ChangePasswordActivity extends BriarActivity
 		String firstPassword = newPassword.getText().toString();
 		String secondPassword = newPasswordConfirmation.getText().toString();
 		boolean passwordsMatch = firstPassword.equals(secondPassword);
-		float strength =
-				passwordController.estimatePasswordStrength(firstPassword);
+		float strength = viewModel.estimatePasswordStrength(firstPassword);
 		strengthMeter.setStrength(strength);
-		UiUtils.setError(newPasswordEntryWrapper,
+		setError(newPasswordEntryWrapper,
 				getString(R.string.password_too_weak),
 				firstPassword.length() > 0 && strength < QUITE_WEAK);
-		UiUtils.setError(newPasswordConfirmationWrapper,
+		setError(newPasswordConfirmationWrapper,
 				getString(R.string.passwords_do_not_match),
 				secondPassword.length() > 0 && !passwordsMatch);
 		changePasswordButton.setEnabled(
@@ -127,32 +138,34 @@ public class ChangePasswordActivity extends BriarActivity
 		// Replace the button with a progress bar
 		changePasswordButton.setVisibility(INVISIBLE);
 		progress.setVisibility(VISIBLE);
-		passwordController.changePassword(currentPassword.getText().toString(),
-				newPassword.getText().toString(),
-				new UiResultHandler<Boolean>(this) {
-					@Override
-					public void onResultUi(@NonNull Boolean result) {
-						if (result) {
-							Toast.makeText(ChangePasswordActivity.this,
-									R.string.password_changed,
-									Toast.LENGTH_LONG).show();
-							setResult(RESULT_OK);
-							supportFinishAfterTransition();
-						} else {
-							tryAgain();
-						}
+
+		String curPwd = currentPassword.getText().toString();
+		String newPwd = newPassword.getText().toString();
+		viewModel.changePassword(curPwd, newPwd).observeEvent(this, result -> {
+					if (result == SUCCESS) {
+						Toast.makeText(ChangePasswordActivity.this,
+								R.string.password_changed,
+								LENGTH_LONG).show();
+						setResult(RESULT_OK);
+						supportFinishAfterTransition();
+					} else {
+						tryAgain(result);
 					}
-				});
+				}
+		);
 	}
 
-	private void tryAgain() {
-		UiUtils.setError(currentPasswordEntryWrapper,
-				getString(R.string.try_again), true);
+	private void tryAgain(DecryptionResult result) {
 		changePasswordButton.setVisibility(VISIBLE);
 		progress.setVisibility(INVISIBLE);
-		currentPassword.setText("");
-
-		// show the keyboard again
-		showSoftKeyboard(currentPassword);
+		if (result == KEY_STRENGTHENER_ERROR) {
+			createKeyStrengthenerErrorDialog(this).show();
+		} else {
+			setError(currentPasswordEntryWrapper,
+					getString(R.string.try_again), true);
+			currentPassword.setText("");
+			// show the keyboard again
+			showSoftKeyboard(currentPassword);
+		}
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/login/ChangePasswordControllerImpl.java

@@ -1,43 +0,0 @@
-package org.briarproject.briar.android.login;
-
-import org.briarproject.bramble.api.account.AccountManager;
-import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.android.controller.handler.ResultHandler;
-
-import java.util.concurrent.Executor;
-
-import javax.inject.Inject;
-
-@NotNullByDefault
-public class ChangePasswordControllerImpl implements ChangePasswordController {
-
-	protected final AccountManager accountManager;
-	protected final Executor ioExecutor;
-	private final PasswordStrengthEstimator strengthEstimator;
-
-	@Inject
-	ChangePasswordControllerImpl(AccountManager accountManager,
-			@IoExecutor Executor ioExecutor,
-			PasswordStrengthEstimator strengthEstimator) {
-		this.accountManager = accountManager;
-		this.ioExecutor = ioExecutor;
-		this.strengthEstimator = strengthEstimator;
-	}
-
-	@Override
-	public float estimatePasswordStrength(String password) {
-		return strengthEstimator.estimateStrength(password);
-	}
-
-	@Override
-	public void changePassword(String oldPassword, String newPassword,
-			ResultHandler<Boolean> resultHandler) {
-		ioExecutor.execute(() -> {
-			boolean changed =
-					accountManager.changePassword(oldPassword, newPassword);
-			resultHandler.onResult(changed);
-		});
-	}
-}

briar-android/src/main/java/org/briarproject/briar/android/login/ChangePasswordViewModel.java

@@ -0,0 +1,53 @@
+package org.briarproject.briar.android.login;
+
+import org.briarproject.bramble.api.account.AccountManager;
+import org.briarproject.bramble.api.crypto.DecryptionException;
+import org.briarproject.bramble.api.crypto.DecryptionResult;
+import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.viewmodel.LiveEvent;
+import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
+
+import java.util.concurrent.Executor;
+
+import javax.inject.Inject;
+
+import androidx.lifecycle.ViewModel;
+
+import static org.briarproject.bramble.api.crypto.DecryptionResult.SUCCESS;
+
+@NotNullByDefault
+public class ChangePasswordViewModel extends ViewModel {
+
+	private final AccountManager accountManager;
+	private final Executor ioExecutor;
+	private final PasswordStrengthEstimator strengthEstimator;
+
+	@Inject
+	ChangePasswordViewModel(AccountManager accountManager,
+			@IoExecutor Executor ioExecutor,
+			PasswordStrengthEstimator strengthEstimator) {
+		this.accountManager = accountManager;
+		this.ioExecutor = ioExecutor;
+		this.strengthEstimator = strengthEstimator;
+	}
+
+	float estimatePasswordStrength(String password) {
+		return strengthEstimator.estimateStrength(password);
+	}
+
+	LiveEvent<DecryptionResult> changePassword(String oldPassword,
+			String newPassword) {
+		MutableLiveEvent<DecryptionResult> result = new MutableLiveEvent<>();
+		ioExecutor.execute(() -> {
+			try {
+				accountManager.changePassword(oldPassword, newPassword);
+				result.postEvent(SUCCESS);
+			} catch (DecryptionException e) {
+				result.postEvent(e.getDecryptionResult());
+			}
+		});
+		return result;
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/login/LoginModule.java

@@ -0,0 +1,23 @@
+package org.briarproject.briar.android.login;
+
+import org.briarproject.briar.android.viewmodel.ViewModelKey;
+
+import androidx.lifecycle.ViewModel;
+import dagger.Binds;
+import dagger.Module;
+import dagger.multibindings.IntoMap;
+
+@Module
+public abstract class LoginModule {
+
+	@Binds
+	@IntoMap
+	@ViewModelKey(StartupViewModel.class)
+	abstract ViewModel bindStartupViewModel(StartupViewModel viewModel);
+
+	@Binds
+	@IntoMap
+	@ViewModelKey(ChangePasswordViewModel.class)
+	abstract ViewModel bindChangePasswordViewModel(
+			ChangePasswordViewModel viewModel);
+}

briar-android/src/main/java/org/briarproject/briar/android/login/LoginUtils.java

@@ -0,0 +1,30 @@
+package org.briarproject.briar.android.login;
+
+import android.content.Context;
+import android.graphics.drawable.Drawable;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.R;
+
+import androidx.appcompat.app.AlertDialog;
+
+import static androidx.core.content.ContextCompat.getColor;
+import static androidx.core.content.ContextCompat.getDrawable;
+import static androidx.core.graphics.drawable.DrawableCompat.setTint;
+import static java.util.Objects.requireNonNull;
+
+@NotNullByDefault
+class LoginUtils {
+
+	static AlertDialog createKeyStrengthenerErrorDialog(Context ctx) {
+		AlertDialog.Builder builder =
+				new AlertDialog.Builder(ctx, R.style.BriarDialogTheme);
+		Drawable icon = getDrawable(ctx, R.drawable.alerts_and_states_error);
+		setTint(requireNonNull(icon), getColor(ctx, R.color.color_primary));
+		builder.setIcon(icon);
+		builder.setTitle(R.string.dialog_title_cannot_check_password);
+		builder.setMessage(R.string.dialog_message_cannot_check_password);
+		builder.setPositiveButton(R.string.ok, null);
+		return builder.create();
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/login/PasswordFragment.java

@@ -12,6 +12,7 @@ import android.widget.ProgressBar;
 import com.google.android.material.textfield.TextInputEditText;
 import com.google.android.material.textfield.TextInputLayout;
 
+import org.briarproject.bramble.api.crypto.DecryptionResult;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
@@ -28,6 +29,9 @@ import androidx.lifecycle.ViewModelProviders;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static android.view.inputmethod.EditorInfo.IME_ACTION_DONE;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.KEY_STRENGTHENER_ERROR;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.SUCCESS;
+import static org.briarproject.briar.android.login.LoginUtils.createKeyStrengthenerErrorDialog;
 import static org.briarproject.briar.android.util.UiUtils.enterPressed;
 import static org.briarproject.briar.android.util.UiUtils.hideSoftKeyboard;
 import static org.briarproject.briar.android.util.UiUtils.setError;
@@ -58,12 +62,13 @@ public class PasswordFragment extends BaseFragment implements TextWatcher {
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 		View v = inflater.inflate(R.layout.fragment_password, container,
-						false);
+				false);
 
 		viewModel = ViewModelProviders.of(requireActivity(), viewModelFactory)
 				.get(StartupViewModel.class);
-		viewModel.getPasswordValidated().observeEvent(this, valid -> {
-			if (!valid) onPasswordInvalid();
+
+		viewModel.getPasswordValidated().observeEvent(this, result -> {
+			if (result != SUCCESS) onPasswordInvalid(result);
 		});
 
 		signInButton = v.findViewById(R.id.btn_sign_in);
@@ -107,18 +112,20 @@ public class PasswordFragment extends BaseFragment implements TextWatcher {
 		viewModel.validatePassword(password.getText().toString());
 	}
 
-	private void onPasswordInvalid() {
-		setError(input, getString(R.string.try_again), true);
+	private void onPasswordInvalid(DecryptionResult result) {
 		signInButton.setVisibility(VISIBLE);
 		progress.setVisibility(INVISIBLE);
-		password.setText(null);
-
-		// show the keyboard again
-		showSoftKeyboard(password);
+		if (result == KEY_STRENGTHENER_ERROR) {
+			createKeyStrengthenerErrorDialog(requireContext()).show();
+		} else {
+			setError(input, getString(R.string.try_again), true);
+			password.setText(null);
+			// show the keyboard again
+			showSoftKeyboard(password);
+		}
 	}
 
-	public void onForgottenPasswordClick() {
-		// TODO Encapsulate the dialog in a re-usable fragment
+	private void onForgottenPasswordClick() {
 		AlertDialog.Builder builder = new AlertDialog.Builder(requireContext(),
 				R.style.BriarDialogTheme);
 		builder.setTitle(R.string.dialog_title_lost_password);

briar-android/src/main/java/org/briarproject/briar/android/login/StartupViewModel.java

@@ -3,6 +3,8 @@ package org.briarproject.briar.android.login;
 import android.app.Application;
 
 import org.briarproject.bramble.api.account.AccountManager;
+import org.briarproject.bramble.api.crypto.DecryptionException;
+import org.briarproject.bramble.api.crypto.DecryptionResult;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
@@ -24,6 +26,7 @@ import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
+import static org.briarproject.bramble.api.crypto.DecryptionResult.SUCCESS;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.COMPACTING_DATABASE;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.MIGRATING_DATABASE;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STARTING_SERVICES;
@@ -46,7 +49,7 @@ public class StartupViewModel extends AndroidViewModel
 	@IoExecutor
 	private final Executor ioExecutor;
 
-	private final MutableLiveEvent<Boolean> passwordValidated =
+	private final MutableLiveEvent<DecryptionResult> passwordValidated =
 			new MutableLiveEvent<>();
 	private final MutableLiveEvent<Boolean> accountDeleted =
 			new MutableLiveEvent<>();
@@ -105,13 +108,17 @@ public class StartupViewModel extends AndroidViewModel
 
 	void validatePassword(String password) {
 		ioExecutor.execute(() -> {
-			boolean signedIn = accountManager.signIn(password);
-			passwordValidated.postEvent(signedIn);
-			if (signedIn) state.postValue(SIGNED_IN);
+			try {
+				accountManager.signIn(password);
+				passwordValidated.postEvent(SUCCESS);
+				state.postValue(SIGNED_IN);
+			} catch (DecryptionException e) {
+				passwordValidated.postEvent(e.getDecryptionResult());
+			}
 		});
 	}
 
-	LiveEvent<Boolean> getPasswordValidated() {
+	LiveEvent<DecryptionResult> getPasswordValidated() {
 		return passwordValidated;
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/util/UiUtils.java

@@ -381,7 +381,7 @@ public class UiUtils {
 	/**
 	 * Same as {@link #observeOnce(LiveData, LifecycleOwner, Observer)},
 	 * but without a {@link LifecycleOwner}.
-	 *
+	 * <p>
 	 * Warning: Do NOT call from objects that have a lifecycle.
 	 */
 	@UiThread
@@ -401,5 +401,4 @@ public class UiUtils {
 		return ctx.getResources().getConfiguration().getLayoutDirection() ==
 				LAYOUT_DIRECTION_RTL;
 	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/viewmodel/ViewModelModule.java

@@ -4,7 +4,6 @@ import org.briarproject.briar.android.contact.add.remote.AddContactViewModel;
 import org.briarproject.briar.android.contact.add.remote.PendingContactListViewModel;
 import org.briarproject.briar.android.conversation.ConversationViewModel;
 import org.briarproject.briar.android.conversation.ImageViewModel;
-import org.briarproject.briar.android.login.StartupViewModel;
 
 import javax.inject.Singleton;
 
@@ -17,11 +16,6 @@ import dagger.multibindings.IntoMap;
 @Module
 public abstract class ViewModelModule {
 
-	@Binds
-	@IntoMap
-	@ViewModelKey(StartupViewModel.class)
-	abstract ViewModel bindStartupViewModel(StartupViewModel startupViewModel);
-
 	@Binds
 	@IntoMap
 	@ViewModelKey(ConversationViewModel.class)

briar-android/src/main/res/values/strings.xml

@@ -32,6 +32,8 @@
 	<!-- Login -->
 	<string name="enter_password">Password</string>
 	<string name="try_again">Wrong password, try again</string>
+	<string name="dialog_title_cannot_check_password">Cannot Check Password</string>
+	<string name="dialog_message_cannot_check_password">Briar cannot check your password. Please try rebooting your device to solve this problem.</string>
 	<string name="sign_in_button">Sign In</string>
 	<string name="forgotten_password">I have forgotten my password</string>
 	<string name="dialog_title_lost_password">Lost Password</string>

briar-android/src/test/java/org/briarproject/briar/android/login/ChangePasswordActivityTest.java

@@ -5,28 +5,30 @@ import android.widget.EditText;
 
 import com.google.android.material.textfield.TextInputLayout;
 
+import org.briarproject.bramble.api.crypto.DecryptionResult;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.TestBriarApplication;
-import org.briarproject.briar.android.controller.handler.ResultHandler;
+import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
-import org.mockito.ArgumentCaptor;
-import org.mockito.Captor;
 import org.mockito.Mock;
-import org.mockito.Mockito;
 import org.mockito.MockitoAnnotations;
 import org.robolectric.Robolectric;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.annotation.Config;
 
 import static junit.framework.Assert.assertEquals;
+import static junit.framework.Assert.assertFalse;
+import static junit.framework.Assert.assertTrue;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.SUCCESS;
 import static org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.NONE;
 import static org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.QUITE_STRONG;
 import static org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.QUITE_WEAK;
 import static org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.STRONG;
 import static org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.WEAK;
+import static org.junit.Assert.assertNotEquals;
 import static org.mockito.Matchers.anyString;
 import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.times;
@@ -37,7 +39,7 @@ import static org.mockito.Mockito.when;
 @Config(sdk = 21, application = TestBriarApplication.class)
 public class ChangePasswordActivityTest {
 
-	private TestChangePasswordActivity changePasswordActivity;
+	private ChangePasswordActivity changePasswordActivity;
 	private TextInputLayout passwordConfirmationWrapper;
 	private EditText currentPassword;
 	private EditText newPassword;
@@ -46,15 +48,14 @@ public class ChangePasswordActivityTest {
 	private Button changePasswordButton;
 
 	@Mock
-	private ChangePasswordController passwordController;
-	@Captor
-	private ArgumentCaptor<ResultHandler<Boolean>> resultCaptor;
+	private ChangePasswordViewModel viewModel;
 
 	@Before
 	public void setUp() {
 		MockitoAnnotations.initMocks(this);
 		changePasswordActivity =
-				Robolectric.setupActivity(TestChangePasswordActivity.class);
+				Robolectric.setupActivity(ChangePasswordActivity.class);
+		changePasswordActivity.viewModel = viewModel;
 		passwordConfirmationWrapper = changePasswordActivity
 				.findViewById(R.id.new_password_confirm_wrapper);
 		currentPassword = changePasswordActivity
@@ -81,7 +82,7 @@ public class ChangePasswordActivityTest {
 		// Password mismatch
 		newPassword.setText("really.safe.password");
 		newPasswordConfirmation.setText("really.safe.pass");
-		assertEquals(changePasswordButton.isEnabled(), false);
+		assertFalse(changePasswordButton.isEnabled());
 		assertEquals(passwordConfirmationWrapper.getError(),
 				changePasswordActivity
 						.getString(R.string.passwords_do_not_match));
@@ -89,70 +90,59 @@ public class ChangePasswordActivityTest {
 		newPassword.setText("really.safe.pass");
 		newPasswordConfirmation.setText("really.safe.pass");
 		// Confirm that the password mismatch error message is not visible
-		Assert.assertNotEquals(passwordConfirmationWrapper.getError(),
+		assertNotEquals(passwordConfirmationWrapper.getError(),
 				changePasswordActivity
 						.getString(R.string.passwords_do_not_match));
 		// Nick has not been set, expect the button to be disabled
-		assertEquals(changePasswordButton.isEnabled(), false);
+		assertFalse(changePasswordButton.isEnabled());
 	}
 
 	@Test
 	public void testChangePasswordUI() {
-		changePasswordActivity.setPasswordController(passwordController);
 		// Mock strong password strength answer
-		when(passwordController.estimatePasswordStrength(anyString()))
+		when(viewModel.estimatePasswordStrength(anyString()))
 				.thenReturn(STRONG);
+		// Mock changing the password
+		MutableLiveEvent<DecryptionResult> result = new MutableLiveEvent<>();
+		when(viewModel.changePassword(anyString(), anyString()))
+				.thenReturn(result);
 		String curPass = "old.password";
 		String safePass = "really.safe.password";
 		currentPassword.setText(curPass);
 		newPassword.setText(safePass);
 		newPasswordConfirmation.setText(safePass);
 		// Confirm that the create account button is clickable
-		assertEquals(changePasswordButton.isEnabled(), true);
+		assertTrue(changePasswordButton.isEnabled());
 		changePasswordButton.performClick();
-		// Verify that the controller's method was called with the correct
-		// params and get the callback
-		verify(passwordController, times(1))
-				.changePassword(eq(curPass), eq(safePass),
-						resultCaptor.capture());
-		// execute the callbacks
-		resultCaptor.getValue().onResult(true);
-		assertEquals(changePasswordActivity.isFinishing(), true);
+		// Verify that the view model was called with the correct params
+		verify(viewModel, times(1)).changePassword(eq(curPass), eq(safePass));
+		// Return the result
+		result.postEvent(SUCCESS);
+		assertTrue(changePasswordActivity.isFinishing());
 	}
 
 	@Test
 	public void testStrengthMeterUI() {
 		Assert.assertNotNull(changePasswordActivity);
-		// replace the password controller with our mocked copy
-		changePasswordActivity.setPasswordController(passwordController);
 		// Mock answers for UI testing only
-		when(passwordController.estimatePasswordStrength("strong")).thenReturn(
-				STRONG);
-		when(passwordController.estimatePasswordStrength("qstrong")).thenReturn(
-				QUITE_STRONG);
-		when(passwordController.estimatePasswordStrength("qweak")).thenReturn(
-				QUITE_WEAK);
-		when(passwordController.estimatePasswordStrength("weak")).thenReturn(
-				WEAK);
-		when(passwordController.estimatePasswordStrength("empty")).thenReturn(
-				NONE);
+		when(viewModel.estimatePasswordStrength("strong")).thenReturn(STRONG);
+		when(viewModel.estimatePasswordStrength("qstrong"))
+				.thenReturn(QUITE_STRONG);
+		when(viewModel.estimatePasswordStrength("qweak"))
+				.thenReturn(QUITE_WEAK);
+		when(viewModel.estimatePasswordStrength("weak")).thenReturn(WEAK);
+		when(viewModel.estimatePasswordStrength("empty")).thenReturn(NONE);
 		// Test the meters progress and color for several values
 		testStrengthMeter("strong", STRONG, StrengthMeter.GREEN);
-		Mockito.verify(passwordController, Mockito.times(1))
-				.estimatePasswordStrength(eq("strong"));
+		verify(viewModel, times(1)).estimatePasswordStrength(eq("strong"));
 		testStrengthMeter("qstrong", QUITE_STRONG, StrengthMeter.LIME);
-		Mockito.verify(passwordController, Mockito.times(1))
-				.estimatePasswordStrength(eq("qstrong"));
+		verify(viewModel, times(1)).estimatePasswordStrength(eq("qstrong"));
 		testStrengthMeter("qweak", QUITE_WEAK, StrengthMeter.YELLOW);
-		Mockito.verify(passwordController, Mockito.times(1))
-				.estimatePasswordStrength(eq("qweak"));
+		verify(viewModel, times(1)).estimatePasswordStrength(eq("qweak"));
 		testStrengthMeter("weak", WEAK, StrengthMeter.ORANGE);
-		Mockito.verify(passwordController, Mockito.times(1))
-				.estimatePasswordStrength(eq("weak"));
+		verify(viewModel, times(1)).estimatePasswordStrength(eq("weak"));
 		// Not sure this should be the correct behaviour on an empty input ?
 		testStrengthMeter("empty", NONE, StrengthMeter.RED);
-		Mockito.verify(passwordController, Mockito.times(1))
-				.estimatePasswordStrength(eq("empty"));
+		verify(viewModel, times(1)).estimatePasswordStrength(eq("empty"));
 	}
-
 }

briar-android/src/test/java/org/briarproject/briar/android/login/ChangePasswordControllerImplTest.java

@@ -1,58 +0,0 @@
-package org.briarproject.briar.android.login;
-
-import org.briarproject.bramble.api.account.AccountManager;
-import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator;
-import org.briarproject.bramble.test.BrambleMockTestCase;
-import org.briarproject.bramble.test.ImmediateExecutor;
-import org.jmock.Expectations;
-import org.junit.Test;
-
-import java.util.concurrent.Executor;
-import java.util.concurrent.atomic.AtomicBoolean;
-
-import static junit.framework.Assert.assertFalse;
-import static junit.framework.Assert.assertTrue;
-import static org.briarproject.bramble.util.StringUtils.getRandomString;
-
-public class ChangePasswordControllerImplTest extends BrambleMockTestCase {
-
-	private final AccountManager accountManager =
-			context.mock(AccountManager.class);
-	private final PasswordStrengthEstimator estimator =
-			context.mock(PasswordStrengthEstimator.class);
-
-	private final Executor ioExecutor = new ImmediateExecutor();
-
-	private final String oldPassword = getRandomString(10);
-	private final String newPassword = getRandomString(10);
-
-	@Test
-	public void testChangePasswordReturnsTrue() {
-		context.checking(new Expectations() {{
-			oneOf(accountManager).changePassword(oldPassword, newPassword);
-			will(returnValue(true));
-		}});
-
-		ChangePasswordControllerImpl p = new ChangePasswordControllerImpl(accountManager,
-				ioExecutor, estimator);
-
-		AtomicBoolean capturedResult = new AtomicBoolean(false);
-		p.changePassword(oldPassword, newPassword, capturedResult::set);
-		assertTrue(capturedResult.get());
-	}
-
-	@Test
-	public void testChangePasswordReturnsFalseIfOldPasswordIsWrong() {
-		context.checking(new Expectations() {{
-			oneOf(accountManager).changePassword(oldPassword, newPassword);
-			will(returnValue(false));
-		}});
-
-		ChangePasswordControllerImpl p = new ChangePasswordControllerImpl(accountManager,
-				ioExecutor, estimator);
-
-		AtomicBoolean capturedResult = new AtomicBoolean(true);
-		p.changePassword(oldPassword, newPassword, capturedResult::set);
-		assertFalse(capturedResult.get());
-	}
-}

briar-android/src/test/java/org/briarproject/briar/android/login/TestChangePasswordActivity.java

@@ -1,14 +0,0 @@
-package org.briarproject.briar.android.login;
-
-/**
- * This class exposes the PasswordController and offers the possibility to
- * replace it.
- */
-public class TestChangePasswordActivity extends ChangePasswordActivity {
-
-	public void setPasswordController(
-			ChangePasswordController passwordController) {
-		this.passwordController = passwordController;
-	}
-
-}

briar-headless/src/main/java/org/briarproject/briar/headless/BriarService.kt

@@ -4,6 +4,7 @@ import com.github.ajalt.clikt.core.UsageError
 import com.github.ajalt.clikt.output.TermUi.echo
 import com.github.ajalt.clikt.output.TermUi.prompt
 import org.briarproject.bramble.api.account.AccountManager
+import org.briarproject.bramble.api.crypto.DecryptionException
 import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator
 import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.QUITE_WEAK
 import org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH
@@ -34,7 +35,9 @@ constructor(
         } else {
             val password = prompt("Password", hideInput = true)
                 ?: throw UsageError("Could not get password. Is STDIN connected?")
-            if (!accountManager.signIn(password)) {
+            try {
+                accountManager.signIn(password)
+            } catch (e : DecryptionException) {
                 echo("Error: Password invalid")
                 exitProcess(1)
             }

briar-headless/src/test/java/org/briarproject/briar/headless/BriarTestServiceImpl.kt

@@ -1,6 +1,7 @@
 package org.briarproject.briar.headless
 
 import org.briarproject.bramble.api.account.AccountManager
+import org.briarproject.bramble.api.crypto.DecryptionException
 import org.briarproject.bramble.api.lifecycle.LifecycleManager
 import javax.annotation.concurrent.Immutable
 import javax.inject.Inject
@@ -23,7 +24,9 @@ constructor(
             accountManager.deleteAccount()
         }
         accountManager.createAccount(user, pass)
-        if (!accountManager.signIn(pass)) {
+        try {
+            accountManager.signIn(pass)
+        } catch (e: DecryptionException) {
             throw AssertionError("Password invalid")
         }
         val dbKey = accountManager.databaseKey ?: throw AssertionError()