Re-encrypt the DB key with the stored key.

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

@@ -153,6 +153,13 @@ public interface CryptoComponent {
 	byte[] decryptWithPassword(byte[] ciphertext, String password,
 			@Nullable KeyStoreConfig keyStoreConfig);
 
+	/**
+	 * Returns true if the given ciphertext was encrypted using a stored key
+	 * to strengthen the password-based key. The validity of the ciphertext is
+	 * not checked.
+	 */
+	boolean isEncryptedWithStoredKey(byte[] ciphertext);
+
 	/**
 	 * Encrypts the given plaintext to the given public key.
 	 */

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.KeyStoreConfig;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.identity.Identity;
@@ -210,13 +211,22 @@ class AccountManagerImpl implements AccountManager {
 			return null;
 		}
 		byte[] ciphertext = fromHexString(hex);
+		KeyStoreConfig keyStoreConfig = databaseConfig.getKeyStoreConfig();
 		byte[] plaintext = crypto.decryptWithPassword(ciphertext, password,
-				databaseConfig.getKeyStoreConfig());
+				keyStoreConfig);
 		if (plaintext == null) {
 			LOG.info("Failed to decrypt database key");
 			return null;
 		}
-		return new SecretKey(plaintext);
+		SecretKey key = new SecretKey(plaintext);
+		// If the DB key was encrypted without using a stored key and a stored
+		// key is now available, re-encrypt the DB key with the stored key
+		if (keyStoreConfig != null &&
+				!crypto.isEncryptedWithStoredKey(ciphertext)) {
+			LOG.info("Re-encrypting database key with stored key");
+			encryptAndStoreDatabaseKey(key, password);
+		}
+		return key;
 	}
 
 	@Override

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

@@ -467,6 +467,12 @@ class CryptoComponentImpl implements CryptoComponent {
 		}
 	}
 
+	@Override
+	public boolean isEncryptedWithStoredKey(byte[] ciphertext) {
+		return ciphertext.length > 0 &&
+				ciphertext[0] == PBKDF_FORMAT_SCRYPT_KEYSTORE;
+	}
+
 	@Override
 	public byte[] encryptToKey(PublicKey publicKey, byte[] plaintext) {
 		try {

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

@@ -118,6 +118,8 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 			oneOf(crypto).decryptWithPassword(encryptedKey, password,
 					keyStoreConfig);
 			will(returnValue(key.getBytes()));
+			oneOf(crypto).isEncryptedWithStoredKey(encryptedKey);
+			will(returnValue(true));
 		}});
 
 		storeDatabaseKey(keyFile, encryptedKeyHex);
@@ -136,6 +138,35 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
 	}
 
+	@Test
+	public void testSignInReEncryptsKey() throws Exception {
+		context.checking(new Expectations() {{
+			oneOf(crypto).decryptWithPassword(encryptedKey, password,
+					keyStoreConfig);
+			will(returnValue(key.getBytes()));
+			oneOf(crypto).isEncryptedWithStoredKey(encryptedKey);
+			will(returnValue(false));
+			oneOf(crypto).encryptWithPassword(key.getBytes(), password,
+					keyStoreConfig);
+			will(returnValue(newEncryptedKey));
+		}});
+
+		storeDatabaseKey(keyFile, encryptedKeyHex);
+		storeDatabaseKey(keyBackupFile, encryptedKeyHex);
+
+		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
+		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
+
+		assertTrue(accountManager.signIn(password));
+		assertTrue(accountManager.hasDatabaseKey());
+		SecretKey decrypted = accountManager.getDatabaseKey();
+		assertNotNull(decrypted);
+		assertArrayEquals(key.getBytes(), decrypted.getBytes());
+
+		assertEquals(newEncryptedKeyHex, loadDatabaseKey(keyFile));
+		assertEquals(newEncryptedKeyHex, loadDatabaseKey(keyBackupFile));
+	}
+
 	@Test
 	public void testDbKeyIsLoadedFromPrimaryFile() throws Exception {
 		storeDatabaseKey(keyFile, encryptedKeyHex);
@@ -316,6 +347,8 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 			oneOf(crypto).decryptWithPassword(encryptedKey, password,
 					keyStoreConfig);
 			will(returnValue(key.getBytes()));
+			oneOf(crypto).isEncryptedWithStoredKey(encryptedKey);
+			will(returnValue(true));
 			oneOf(crypto).encryptWithPassword(key.getBytes(), newPassword,
 					keyStoreConfig);
 			will(returnValue(newEncryptedKey));