refactor storage to handle different persistence strategies

drongo

@@ -1 +1 @@
-Subproject commit cc32285d58fcd1120b27797ff1d882ae4ae8a1ed
+Subproject commit 7dca0d0c39404bd89a5a4589a79ffe0f688e8181

src/main/java/com/sparrowwallet/sparrow/AppController.java

@@ -740,13 +740,8 @@ public class AppController implements Initializable {
             Storage storage = new Storage(file);
             FileType fileType = IOUtils.getFileType(file);
             if(FileType.JSON.equals(fileType)) {
-                Storage.WalletBackupAndKey walletBackupAndKey = storage.loadWallet();
+                WalletBackupAndKey walletBackupAndKey = storage.loadUnencryptedWallet();
-                checkWalletNetwork(walletBackupAndKey.wallet);
+                openWallet(storage, walletBackupAndKey, this, forceSameWindow);
-                restorePublicKeysFromSeed(walletBackupAndKey.wallet, null);
-                if(!walletBackupAndKey.wallet.isValid()) {
-                    throw new IllegalStateException("Wallet file is not valid.");
-                }
-                addWalletTabOrWindow(storage, walletBackupAndKey.wallet, walletBackupAndKey.backupWallet, forceSameWindow);
             } else if(FileType.BINARY.equals(fileType)) {
                 WalletPasswordDialog dlg = new WalletPasswordDialog(file.getName(), WalletPasswordDialog.PasswordRequirement.LOAD);
                 Optional<SecureString> optionalPassword = dlg.showAndWait();
@@ -758,16 +753,8 @@ public class AppController implements Initializable {
                 Storage.LoadWalletService loadWalletService = new Storage.LoadWalletService(storage, password);
                 loadWalletService.setOnSucceeded(workerStateEvent -> {
                     EventManager.get().post(new StorageEvent(storage.getWalletFile(), TimedEvent.Action.END, "Done"));
-                    Storage.WalletBackupAndKey walletBackupAndKey = loadWalletService.getValue();
+                    WalletBackupAndKey walletBackupAndKey = loadWalletService.getValue();
-                    try {
+                    openWallet(storage, walletBackupAndKey, this, forceSameWindow);
-                        checkWalletNetwork(walletBackupAndKey.wallet);
-                        restorePublicKeysFromSeed(walletBackupAndKey.wallet, walletBackupAndKey.key);
-                        addWalletTabOrWindow(storage, walletBackupAndKey.wallet, walletBackupAndKey.backupWallet, forceSameWindow);
-                    } catch(Exception e) {
-                        showErrorDialog("Error Opening Wallet", e.getMessage());
-                    } finally {
-                        walletBackupAndKey.key.clear();
-                    }
                 });
                 loadWalletService.setOnFailed(workerStateEvent -> {
                     EventManager.get().post(new StorageEvent(storage.getWalletFile(), TimedEvent.Action.END, "Failed"));
@@ -798,6 +785,25 @@ public class AppController implements Initializable {
         }
     }
 
+    private void openWallet(Storage storage, WalletBackupAndKey walletBackupAndKey, AppController appController, boolean forceSameWindow) {
+        try {
+            checkWalletNetwork(walletBackupAndKey.getWallet());
+            restorePublicKeysFromSeed(walletBackupAndKey.getWallet(), walletBackupAndKey.getKey());
+            if(!walletBackupAndKey.getWallet().isValid()) {
+                throw new IllegalStateException("Wallet file is not valid.");
+            }
+            AppController walletAppController = appController.addWalletTabOrWindow(storage, walletBackupAndKey.getWallet(), walletBackupAndKey.getBackupWallet(), forceSameWindow);
+            for(Map.Entry<Storage, WalletBackupAndKey> entry : walletBackupAndKey.getChildWallets().entrySet()) {
+                openWallet(entry.getKey(), entry.getValue(), walletAppController, true);
+            }
+            Platform.runLater(() -> selectTab(walletBackupAndKey.getWallet()));
+        } catch(Exception e) {
+            showErrorDialog("Error Opening Wallet", e.getMessage());
+        } finally {
+            walletBackupAndKey.clear();
+        }
+    }
+
     private void checkWalletNetwork(Wallet wallet) {
         if(wallet.getNetwork() != null && wallet.getNetwork() != Network.get()) {
             throw new IllegalStateException("Provided " + wallet.getNetwork() + " wallet is invalid on a " + Network.get() + " network. Use a " + wallet.getNetwork() + " configuration to load this wallet.");
@@ -937,7 +943,7 @@ public class AppController implements Initializable {
             if(password.get().length() == 0) {
                 try {
                     storage.setEncryptionPubKey(Storage.NO_PASSWORD_KEY);
-                    storage.storeWallet(wallet);
+                    storage.saveWallet(wallet);
                     addWalletTabOrWindow(storage, wallet, null, false);
                 } catch(IOException e) {
                     log.error("Error saving imported wallet", e);
@@ -954,7 +960,7 @@ public class AppController implements Initializable {
                         key = new Key(encryptionFullKey.getPrivKeyBytes(), storage.getKeyDeriver().getSalt(), EncryptionType.Deriver.ARGON2);
                         wallet.encrypt(key);
                         storage.setEncryptionPubKey(encryptionPubKey);
-                        storage.storeWallet(wallet);
+                        storage.saveWallet(wallet);
                         addWalletTabOrWindow(storage, wallet, null, false);
                     } catch(IOException e) {
                         log.error("Error saving imported wallet", e);
@@ -1032,14 +1038,14 @@ public class AppController implements Initializable {
         }
     }
 
-    public void addWalletTabOrWindow(Storage storage, Wallet wallet, Wallet backupWallet, boolean forceSameWindow) {
+    public AppController addWalletTabOrWindow(Storage storage, Wallet wallet, Wallet backupWallet, boolean forceSameWindow) {
         Window existingWalletWindow = AppServices.get().getWindowForWallet(storage);
         if(existingWalletWindow instanceof Stage) {
             Stage existingWalletStage = (Stage)existingWalletWindow;
             existingWalletStage.toFront();
 
             EventManager.get().post(new ViewWalletEvent(existingWalletWindow, wallet, storage));
-            return;
+            return this;
         }
 
         if(!forceSameWindow && Config.get().isOpenWalletsInNewWindows() && !getOpenWallets().isEmpty()) {
@@ -1048,8 +1054,10 @@ public class AppController implements Initializable {
             stage.toFront();
             stage.setX(AppServices.get().getWalletWindowMaxX() + 30);
             appController.addWalletTab(storage, wallet, backupWallet);
+            return appController;
         } else {
             addWalletTab(storage, wallet, backupWallet);
+            return this;
         }
     }
 

src/main/java/com/sparrowwallet/sparrow/AppServices.java

@@ -825,7 +825,7 @@ public class AppServices {
 
         Platform.runLater(() -> {
             if(!Window.getWindows().isEmpty()) {
-                List<File> walletFiles = allWallets.stream().map(walletTabData -> walletTabData.getStorage().getWalletFile()).collect(Collectors.toList());
+                List<File> walletFiles = allWallets.stream().filter(walletTabData -> walletTabData.getWallet().getMasterWallet() == null).map(walletTabData -> walletTabData.getStorage().getWalletFile()).collect(Collectors.toList());
                 Config.get().setRecentWalletFiles(Config.get().isLoadRecentWallets() ? walletFiles : Collections.emptyList());
             }
         });

src/main/java/com/sparrowwallet/sparrow/io/ColdcardMultisig.java

@@ -36,7 +36,7 @@ public class ColdcardMultisig implements WalletImport, KeystoreFileImport, Walle
     @Override
     public Keystore getKeystore(ScriptType scriptType, InputStream inputStream, String password) throws ImportException {
         InputStreamReader reader = new InputStreamReader(inputStream, StandardCharsets.UTF_8);
-        ColdcardKeystore cck = Storage.getGson().fromJson(reader, ColdcardKeystore.class);
+        ColdcardKeystore cck = JsonPersistence.getGson().fromJson(reader, ColdcardKeystore.class);
 
         Keystore keystore = new Keystore("Coldcard");
         keystore.setSource(KeystoreSource.HW_AIRGAPPED);

src/main/java/com/sparrowwallet/sparrow/io/JsonPersistence.java

@@ -0,0 +1,412 @@
+package com.sparrowwallet.sparrow.io;
+
+import com.google.gson.*;
+import com.sparrowwallet.drongo.ExtendedKey;
+import com.sparrowwallet.drongo.Utils;
+import com.sparrowwallet.drongo.crypto.Argon2KeyDeriver;
+import com.sparrowwallet.drongo.crypto.AsymmetricKeyDeriver;
+import com.sparrowwallet.drongo.crypto.ECKey;
+import com.sparrowwallet.drongo.protocol.Sha256Hash;
+import com.sparrowwallet.drongo.protocol.Transaction;
+import com.sparrowwallet.drongo.wallet.Keystore;
+import com.sparrowwallet.drongo.wallet.Wallet;
+import com.sparrowwallet.drongo.wallet.WalletNode;
+
+import java.io.*;
+import java.lang.reflect.Type;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.security.SecureRandom;
+import java.util.*;
+import java.util.zip.DeflaterOutputStream;
+import java.util.zip.InflaterInputStream;
+
+import static com.sparrowwallet.drongo.crypto.Argon2KeyDeriver.SPRW1_PARAMETERS;
+
+public class JsonPersistence implements Persistence {
+    public static final String HEADER_MAGIC_1 = "SPRW1";
+    public static final int BINARY_HEADER_LENGTH = 28;
+
+    private final Gson gson;
+    private AsymmetricKeyDeriver keyDeriver;
+
+    public JsonPersistence() {
+        this.gson = getGson();
+    }
+
+    public Wallet loadWallet(File jsonFile) throws IOException {
+        try(Reader reader = new FileReader(jsonFile)) {
+            return gson.fromJson(reader, Wallet.class);
+        }
+    }
+
+    public WalletBackupAndKey loadWallet(File walletFile, CharSequence password) throws IOException, StorageException {
+        Wallet wallet;
+        ECKey encryptionKey;
+
+        try(InputStream fileStream = new FileInputStream(walletFile)) {
+            encryptionKey = getEncryptionKey(password, fileStream, null);
+            Reader reader = new InputStreamReader(new InflaterInputStream(new ECIESInputStream(fileStream, encryptionKey, getEncryptionMagic())), StandardCharsets.UTF_8);
+            wallet = gson.fromJson(reader, Wallet.class);
+        }
+
+        return new WalletBackupAndKey(wallet, null, encryptionKey, keyDeriver, null);
+    }
+
+    public Map<File, Wallet> loadWallets(File[] walletFiles, ECKey encryptionKey) throws IOException, StorageException {
+        Map<File, Wallet> walletsMap = new LinkedHashMap<>();
+        for(File file : walletFiles) {
+            if(encryptionKey != null) {
+                try(InputStream fileStream = new FileInputStream(file)) {
+                    encryptionKey = getEncryptionKey(null, fileStream, encryptionKey);
+                    Reader reader = new InputStreamReader(new InflaterInputStream(new ECIESInputStream(fileStream, encryptionKey, getEncryptionMagic())), StandardCharsets.UTF_8);
+                    walletsMap.put(file, gson.fromJson(reader, Wallet.class));
+                }
+            } else {
+                walletsMap.put(file, loadWallet(file));
+            }
+        }
+
+        return walletsMap;
+    }
+
+    public Map<Storage, WalletBackupAndKey> loadChildWallets(File walletFile, Wallet masterWallet, ECKey encryptionKey) throws IOException, StorageException {
+        File[] walletFiles = getChildWalletFiles(walletFile, masterWallet);
+        Map<Storage, WalletBackupAndKey> childWallets = new LinkedHashMap<>();
+        Map<File, Wallet> loadedWallets = loadWallets(walletFiles, encryptionKey);
+        for(Map.Entry<File, Wallet> entry : loadedWallets.entrySet()) {
+            Storage storage = new Storage(entry.getKey());
+            storage.setEncryptionPubKey(ECKey.fromPublicOnly(encryptionKey));
+            storage.setKeyDeriver(getKeyDeriver());
+            Wallet childWallet = entry.getValue();
+            childWallet.setMasterWallet(masterWallet);
+            childWallets.put(storage, new WalletBackupAndKey(childWallet, null, encryptionKey, keyDeriver, Collections.emptyMap()));
+        }
+
+        return childWallets;
+    }
+
+    private File[] getChildWalletFiles(File walletFile, Wallet masterWallet) {
+        File childDir = new File(walletFile.getParentFile(), masterWallet.getName() + "-child");
+        if(!childDir.exists()) {
+            return new File[0];
+        }
+
+        File[] childFiles = childDir.listFiles(pathname -> {
+            FileType fileType = IOUtils.getFileType(pathname);
+            return pathname.getName().startsWith(masterWallet.getName()) && (fileType == FileType.BINARY || fileType == FileType.JSON);
+        });
+
+        return childFiles == null ? new File[0] : childFiles;
+    }
+
+    public File storeWallet(File walletFile, Wallet wallet) throws IOException {
+        File parent = walletFile.getParentFile();
+        if(!parent.exists() && !Storage.createOwnerOnlyDirectory(parent)) {
+            throw new IOException("Could not create folder " + parent);
+        }
+
+        if(!walletFile.getName().endsWith(".json")) {
+            File jsonFile = new File(parent, walletFile.getName() + ".json");
+            if(walletFile.exists()) {
+                if(!walletFile.renameTo(jsonFile)) {
+                    throw new IOException("Could not rename " + walletFile.getName() + " to " + jsonFile.getName());
+                }
+            }
+            walletFile = jsonFile;
+        }
+
+        if(!walletFile.exists()) {
+            Storage.createOwnerOnlyFile(walletFile);
+        }
+
+        try(Writer writer = new FileWriter(walletFile)) {
+            gson.toJson(wallet, writer);
+        }
+
+        return walletFile;
+    }
+
+    public File storeWallet(File walletFile, Wallet wallet, ECKey encryptionPubKey) throws IOException {
+        File parent = walletFile.getParentFile();
+        if(!parent.exists() && !Storage.createOwnerOnlyDirectory(parent)) {
+            throw new IOException("Could not create folder " + parent);
+        }
+
+        if(walletFile.getName().endsWith(".json")) {
+            File noJsonFile = new File(parent, walletFile.getName().substring(0, walletFile.getName().lastIndexOf('.')));
+            if(walletFile.exists()) {
+                if(!walletFile.renameTo(noJsonFile)) {
+                    throw new IOException("Could not rename " + walletFile.getName() + " to " + noJsonFile.getName());
+                }
+            }
+            walletFile = noJsonFile;
+        }
+
+        if(!walletFile.exists()) {
+            Storage.createOwnerOnlyFile(walletFile);
+        }
+
+        try(OutputStream outputStream = new FileOutputStream(walletFile)) {
+            writeBinaryHeader(outputStream);
+            OutputStreamWriter writer = new OutputStreamWriter(new DeflaterOutputStream(new ECIESOutputStream(outputStream, encryptionPubKey, getEncryptionMagic())), StandardCharsets.UTF_8);
+            gson.toJson(wallet, writer);
+            //Close the writer explicitly as the try-resources block will not do so
+            writer.close();
+        }
+
+        return walletFile;
+    }
+
+    private void writeBinaryHeader(OutputStream outputStream) throws IOException {
+        ByteBuffer buf = ByteBuffer.allocate(21);
+        buf.put(HEADER_MAGIC_1.getBytes(StandardCharsets.UTF_8));
+        buf.put(keyDeriver.getSalt());
+
+        byte[] encoded = Base64.getEncoder().encode(buf.array());
+        if(encoded.length != BINARY_HEADER_LENGTH) {
+            throw new IllegalStateException("Header length not " + BINARY_HEADER_LENGTH + " bytes");
+        }
+        outputStream.write(encoded);
+    }
+
+    private static byte[] getEncryptionMagic() {
+        return "BIE1".getBytes(StandardCharsets.UTF_8);
+    }
+
+    public ECKey getEncryptionKey(CharSequence password) throws IOException, StorageException {
+        return getEncryptionKey(password, null, null);
+    }
+
+    private ECKey getEncryptionKey(CharSequence password, InputStream inputStream, ECKey alreadyDerivedKey) throws IOException, StorageException {
+        if(password != null && password.equals("")) {
+            return Storage.NO_PASSWORD_KEY;
+        }
+
+        AsymmetricKeyDeriver keyDeriver = getKeyDeriver(inputStream);
+        return alreadyDerivedKey == null ?  keyDeriver.deriveECKey(password) : alreadyDerivedKey;
+    }
+
+    public AsymmetricKeyDeriver getKeyDeriver() {
+        return keyDeriver;
+    }
+
+    public void setKeyDeriver(AsymmetricKeyDeriver keyDeriver) {
+        this.keyDeriver = keyDeriver;
+    }
+
+    private AsymmetricKeyDeriver getKeyDeriver(InputStream inputStream) throws IOException, StorageException {
+        if(keyDeriver == null) {
+            keyDeriver = getWalletKeyDeriver(inputStream);
+        } else if(inputStream != null) {
+            inputStream.skip(BINARY_HEADER_LENGTH);
+        }
+
+        return keyDeriver;
+    }
+
+    private AsymmetricKeyDeriver getWalletKeyDeriver(InputStream inputStream) throws IOException, StorageException {
+        byte[] salt = new byte[SPRW1_PARAMETERS.saltLength];
+
+        if(inputStream != null) {
+            byte[] header = new byte[BINARY_HEADER_LENGTH];
+            int read = inputStream.read(header);
+            if(read != BINARY_HEADER_LENGTH) {
+                throw new StorageException("Not a Sparrow wallet - invalid header");
+            }
+            try {
+                byte[] decodedHeader = Base64.getDecoder().decode(header);
+                byte[] magic = Arrays.copyOfRange(decodedHeader, 0, HEADER_MAGIC_1.length());
+                if(!HEADER_MAGIC_1.equals(new String(magic, StandardCharsets.UTF_8))) {
+                    throw new StorageException("Not a Sparrow wallet - invalid magic");
+                }
+                salt = Arrays.copyOfRange(decodedHeader, HEADER_MAGIC_1.length(), decodedHeader.length);
+            } catch(IllegalArgumentException e) {
+                throw new StorageException("Not a Sparrow wallet - invalid header");
+            }
+        } else {
+            SecureRandom secureRandom = new SecureRandom();
+            secureRandom.nextBytes(salt);
+        }
+
+        return new Argon2KeyDeriver(salt);
+    }
+
+    public PersistenceType getType() {
+        return PersistenceType.JSON;
+    }
+
+    public static Gson getGson() {
+        return getGson(true);
+    }
+
+    private static Gson getGson(boolean includeWalletSerializers) {
+        GsonBuilder gsonBuilder = new GsonBuilder();
+        gsonBuilder.registerTypeAdapter(ExtendedKey.class, new ExtendedPublicKeySerializer());
+        gsonBuilder.registerTypeAdapter(ExtendedKey.class, new ExtendedPublicKeyDeserializer());
+        gsonBuilder.registerTypeAdapter(byte[].class, new ByteArraySerializer());
+        gsonBuilder.registerTypeAdapter(byte[].class, new ByteArrayDeserializer());
+        gsonBuilder.registerTypeAdapter(Sha256Hash.class, new Sha256HashSerializer());
+        gsonBuilder.registerTypeAdapter(Sha256Hash.class, new Sha256HashDeserializer());
+        gsonBuilder.registerTypeAdapter(Date.class, new DateSerializer());
+        gsonBuilder.registerTypeAdapter(Date.class, new DateDeserializer());
+        gsonBuilder.registerTypeAdapter(Transaction.class, new TransactionSerializer());
+        gsonBuilder.registerTypeAdapter(Transaction.class, new TransactionDeserializer());
+        if(includeWalletSerializers) {
+            gsonBuilder.registerTypeAdapter(Keystore.class, new KeystoreSerializer());
+            gsonBuilder.registerTypeAdapter(WalletNode.class, new NodeSerializer());
+            gsonBuilder.registerTypeAdapter(WalletNode.class, new NodeDeserializer());
+        }
+
+        gsonBuilder.addSerializationExclusionStrategy(new ExclusionStrategy() {
+            @Override
+            public boolean shouldSkipField(FieldAttributes field) {
+                return field.getDeclaringClass() == Wallet.class && field.getName().equals("masterWallet");
+            }
+
+            @Override
+            public boolean shouldSkipClass(Class<?> clazz) {
+                return false;
+            }
+        });
+
+        return gsonBuilder.setPrettyPrinting().disableHtmlEscaping().create();
+    }
+
+    private static class ExtendedPublicKeySerializer implements JsonSerializer<ExtendedKey> {
+        @Override
+        public JsonElement serialize(ExtendedKey src, Type typeOfSrc, JsonSerializationContext context) {
+            return new JsonPrimitive(src.toString());
+        }
+    }
+
+    private static class ExtendedPublicKeyDeserializer implements JsonDeserializer<ExtendedKey> {
+        @Override
+        public ExtendedKey deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+            return ExtendedKey.fromDescriptor(json.getAsJsonPrimitive().getAsString());
+        }
+    }
+
+    private static class ByteArraySerializer implements JsonSerializer<byte[]> {
+        @Override
+        public JsonElement serialize(byte[] src, Type typeOfSrc, JsonSerializationContext context) {
+            return new JsonPrimitive(Utils.bytesToHex(src));
+        }
+    }
+
+    private static class ByteArrayDeserializer implements JsonDeserializer<byte[]> {
+        @Override
+        public byte[] deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+            return Utils.hexToBytes(json.getAsJsonPrimitive().getAsString());
+        }
+    }
+
+    private static class Sha256HashSerializer implements JsonSerializer<Sha256Hash> {
+        @Override
+        public JsonElement serialize(Sha256Hash src, Type typeOfSrc, JsonSerializationContext context) {
+            return new JsonPrimitive(src.toString());
+        }
+    }
+
+    private static class Sha256HashDeserializer implements JsonDeserializer<Sha256Hash> {
+        @Override
+        public Sha256Hash deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+            return Sha256Hash.wrap(json.getAsJsonPrimitive().getAsString());
+        }
+    }
+
+    private static class DateSerializer implements JsonSerializer<Date> {
+        @Override
+        public JsonElement serialize(Date src, Type typeOfSrc, JsonSerializationContext context) {
+            return new JsonPrimitive(src.getTime());
+        }
+    }
+
+    private static class DateDeserializer implements JsonDeserializer<Date> {
+        @Override
+        public Date deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+            return new Date(json.getAsJsonPrimitive().getAsLong());
+        }
+    }
+
+    private static class TransactionSerializer implements JsonSerializer<Transaction> {
+        @Override
+        public JsonElement serialize(Transaction src, Type typeOfSrc, JsonSerializationContext context) {
+            try {
+                ByteArrayOutputStream baos = new ByteArrayOutputStream();
+                src.bitcoinSerializeToStream(baos);
+                return new JsonPrimitive(Utils.bytesToHex(baos.toByteArray()));
+            } catch (IOException e) {
+                throw new IllegalStateException(e);
+            }
+        }
+    }
+
+    private static class TransactionDeserializer implements JsonDeserializer<Transaction> {
+        @Override
+        public Transaction deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+            byte[] rawTx = Utils.hexToBytes(json.getAsJsonPrimitive().getAsString());
+            return new Transaction(rawTx);
+        }
+    }
+
+    private static class KeystoreSerializer implements JsonSerializer<Keystore> {
+        @Override
+        public JsonElement serialize(Keystore keystore, Type typeOfSrc, JsonSerializationContext context) {
+            JsonObject jsonObject = (JsonObject)getGson(false).toJsonTree(keystore);
+            if(keystore.hasPrivateKey()) {
+                jsonObject.remove("extendedPublicKey");
+                jsonObject.getAsJsonObject("keyDerivation").remove("masterFingerprint");
+            }
+
+            return jsonObject;
+        }
+    }
+
+    private static class NodeSerializer implements JsonSerializer<WalletNode> {
+        @Override
+        public JsonElement serialize(WalletNode node, Type typeOfSrc, JsonSerializationContext context) {
+            JsonObject jsonObject = (JsonObject)getGson(false).toJsonTree(node);
+
+            JsonArray children = jsonObject.getAsJsonArray("children");
+            Iterator<JsonElement> iter = children.iterator();
+            while(iter.hasNext()) {
+                JsonObject childObject = (JsonObject)iter.next();
+                removeEmptyCollection(childObject, "children");
+                removeEmptyCollection(childObject, "transactionOutputs");
+
+                if(childObject.get("label") == null && childObject.get("children") == null && childObject.get("transactionOutputs") == null) {
+                    iter.remove();
+                }
+            }
+
+            return jsonObject;
+        }
+
+        private void removeEmptyCollection(JsonObject jsonObject, String memberName) {
+            if(jsonObject.get(memberName) != null && jsonObject.getAsJsonArray(memberName).size() == 0) {
+                jsonObject.remove(memberName);
+            }
+        }
+    }
+
+    private static class NodeDeserializer implements JsonDeserializer<WalletNode> {
+        @Override
+        public WalletNode deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+            WalletNode node = getGson(false).fromJson(json, typeOfT);
+            node.parseDerivation();
+
+            for(WalletNode childNode : node.getChildren()) {
+                childNode.parseDerivation();
+                if(childNode.getChildren() == null) {
+                    childNode.setChildren(new TreeSet<>());
+                }
+                if(childNode.getTransactionOutputs() == null) {
+                    childNode.setTransactionOutputs(new TreeSet<>());
+                }
+            }
+
+            return node;
+        }
+    }
+}

src/main/java/com/sparrowwallet/sparrow/io/Persistence.java

@@ -0,0 +1,22 @@
+package com.sparrowwallet.sparrow.io;
+
+import com.sparrowwallet.drongo.crypto.AsymmetricKeyDeriver;
+import com.sparrowwallet.drongo.crypto.ECKey;
+import com.sparrowwallet.drongo.wallet.Wallet;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Map;
+
+public interface Persistence {
+    Wallet loadWallet(File walletFile) throws IOException;
+    WalletBackupAndKey loadWallet(File walletFile, CharSequence password) throws IOException, StorageException;
+    Map<File, Wallet> loadWallets(File[] walletFiles, ECKey encryptionKey) throws IOException, StorageException;
+    Map<Storage, WalletBackupAndKey> loadChildWallets(File walletFile, Wallet masterWallet, ECKey encryptionKey) throws IOException, StorageException;
+    File storeWallet(File walletFile, Wallet wallet) throws IOException;
+    File storeWallet(File walletFile, Wallet wallet, ECKey encryptionPubKey) throws IOException;
+    ECKey getEncryptionKey(CharSequence password) throws IOException, StorageException;
+    AsymmetricKeyDeriver getKeyDeriver();
+    void setKeyDeriver(AsymmetricKeyDeriver keyDeriver);
+    PersistenceType getType();
+}

src/main/java/com/sparrowwallet/sparrow/io/PersistenceType.java

@@ -0,0 +1,19 @@
+package com.sparrowwallet.sparrow.io;
+
+public enum PersistenceType {
+    JSON("json");
+
+    private final String name;
+
+    private PersistenceType(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getExtension() {
+        return getName();
+    }
+}

src/main/java/com/sparrowwallet/sparrow/io/Storage.java

@@ -1,16 +1,10 @@
 package com.sparrowwallet.sparrow.io;
 
-import com.google.gson.*;
-import com.sparrowwallet.drongo.ExtendedKey;
 import com.sparrowwallet.drongo.Network;
 import com.sparrowwallet.drongo.SecureString;
 import com.sparrowwallet.drongo.Utils;
 import com.sparrowwallet.drongo.crypto.*;
-import com.sparrowwallet.drongo.protocol.Sha256Hash;
-import com.sparrowwallet.drongo.protocol.Transaction;
-import com.sparrowwallet.drongo.wallet.Keystore;
 import com.sparrowwallet.drongo.wallet.Wallet;
-import com.sparrowwallet.drongo.wallet.WalletNode;
 import com.sparrowwallet.sparrow.MainApp;
 import javafx.concurrent.Service;
 import javafx.concurrent.Task;
@@ -19,13 +13,9 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.*;
-import java.lang.reflect.Type;
-import java.nio.ByteBuffer;
-import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.attribute.PosixFilePermission;
 import java.nio.file.attribute.PosixFilePermissions;
-import java.security.SecureRandom;
 import java.security.cert.Certificate;
 import java.security.cert.CertificateEncodingException;
 import java.text.DateFormat;
@@ -33,9 +23,6 @@ import java.text.SimpleDateFormat;
 import java.util.*;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
-import java.util.zip.*;
-
-import static com.sparrowwallet.drongo.crypto.Argon2KeyDeriver.SPRW1_PARAMETERS;
 
 public class Storage {
     private static final Logger log = LoggerFactory.getLogger(Storage.class);
@@ -49,173 +36,60 @@ public class Storage {
     public static final String WALLETS_DIR = "wallets";
     public static final String WALLETS_BACKUP_DIR = "backup";
     public static final String CERTS_DIR = "certs";
-    public static final String HEADER_MAGIC_1 = "SPRW1";
-    private static final int BINARY_HEADER_LENGTH = 28;
     public static final String TEMP_BACKUP_EXTENSION = "tmp";
 
+    private final Persistence persistence;
     private File walletFile;
-    private final Gson gson;
-    private AsymmetricKeyDeriver keyDeriver;
     private ECKey encryptionPubKey;
 
     public Storage(File walletFile) {
+        this.persistence = new JsonPersistence();
         this.walletFile = walletFile;
-        this.gson = getGson();
     }
 
     public File getWalletFile() {
         return walletFile;
     }
 
-    public static Gson getGson() {
+    public WalletBackupAndKey loadUnencryptedWallet() throws IOException, StorageException {
-        return getGson(true);
+        Wallet wallet = persistence.loadWallet(walletFile);
-    }
+        Wallet backupWallet = loadBackupWallet(null);
-
+        Map<Storage, WalletBackupAndKey> childWallets = persistence.loadChildWallets(walletFile, wallet, null);
-    private static Gson getGson(boolean includeWalletSerializers) {
-        GsonBuilder gsonBuilder = new GsonBuilder();
-        gsonBuilder.registerTypeAdapter(ExtendedKey.class, new ExtendedPublicKeySerializer());
-        gsonBuilder.registerTypeAdapter(ExtendedKey.class, new ExtendedPublicKeyDeserializer());
-        gsonBuilder.registerTypeAdapter(byte[].class, new ByteArraySerializer());
-        gsonBuilder.registerTypeAdapter(byte[].class, new ByteArrayDeserializer());
-        gsonBuilder.registerTypeAdapter(Sha256Hash.class, new Sha256HashSerializer());
-        gsonBuilder.registerTypeAdapter(Sha256Hash.class, new Sha256HashDeserializer());
-        gsonBuilder.registerTypeAdapter(Date.class, new DateSerializer());
-        gsonBuilder.registerTypeAdapter(Date.class, new DateDeserializer());
-        gsonBuilder.registerTypeAdapter(Transaction.class, new TransactionSerializer());
-        gsonBuilder.registerTypeAdapter(Transaction.class, new TransactionDeserializer());
-        if(includeWalletSerializers) {
-            gsonBuilder.registerTypeAdapter(Keystore.class, new KeystoreSerializer());
-            gsonBuilder.registerTypeAdapter(WalletNode.class, new NodeSerializer());
-            gsonBuilder.registerTypeAdapter(WalletNode.class, new NodeDeserializer());
-        }
-
-        return gsonBuilder.setPrettyPrinting().disableHtmlEscaping().create();
-    }
-
-    public WalletBackupAndKey loadWallet() throws IOException {
-        Wallet wallet = loadWallet(walletFile);
-
-        Wallet backupWallet = null;
-        File[] backups = getBackups("json." + TEMP_BACKUP_EXTENSION);
-        if(backups.length > 0) {
-            try {
-                backupWallet = loadWallet(backups[0]);
-            } catch(Exception e) {
-                log.error("Error loading backup wallet " + TEMP_BACKUP_EXTENSION, e);
-            }
-        }
 
         encryptionPubKey = NO_PASSWORD_KEY;
-        return new WalletBackupAndKey(wallet, backupWallet, null);
+        return new WalletBackupAndKey(wallet, backupWallet, null, null, childWallets);
     }
 
-    public Wallet loadWallet(File jsonFile) throws IOException {
+    public WalletBackupAndKey loadEncryptedWallet(CharSequence password) throws IOException, StorageException {
-        Reader reader = new FileReader(jsonFile);
+        WalletBackupAndKey masterWalletAndKey = persistence.loadWallet(walletFile, password);
-        Wallet wallet = gson.fromJson(reader, Wallet.class);
+        Wallet backupWallet = loadBackupWallet(masterWalletAndKey.getEncryptionKey());
-        reader.close();
+        Map<Storage, WalletBackupAndKey> childWallets = persistence.loadChildWallets(walletFile, masterWalletAndKey.getWallet(), masterWalletAndKey.getEncryptionKey());
 
-        return wallet;
+        encryptionPubKey = ECKey.fromPublicOnly(masterWalletAndKey.getEncryptionKey());
+        return new WalletBackupAndKey(masterWalletAndKey.getWallet(), backupWallet, masterWalletAndKey.getEncryptionKey(), persistence.getKeyDeriver(), childWallets);
     }
 
-    public WalletBackupAndKey loadWallet(CharSequence password) throws IOException, StorageException {
+    protected Wallet loadBackupWallet(ECKey encryptionKey) throws IOException, StorageException {
-        WalletAndKey walletAndKey = loadWallet(walletFile, password);
+        Map<File, Wallet> backupWallets;
-
+        if(encryptionKey != null) {
-        WalletAndKey backupAndKey = new WalletAndKey(null, null);
+            File[] backups = getBackups(TEMP_BACKUP_EXTENSION, persistence.getType().getExtension() + "." + TEMP_BACKUP_EXTENSION);
-        File[] backups = getBackups(TEMP_BACKUP_EXTENSION, "json." + TEMP_BACKUP_EXTENSION);
+            backupWallets = persistence.loadWallets(backups, encryptionKey);
-        if(backups.length > 0) {
+            return backupWallets.isEmpty() ? null : backupWallets.values().iterator().next();
-            try {
+        } else {
-                backupAndKey = loadWallet(backups[0], password);
+            File[] backups = getBackups(persistence.getType().getExtension() + "." + TEMP_BACKUP_EXTENSION);
-            } catch(Exception e) {
+            backupWallets = persistence.loadWallets(backups, null);
-                log.error("Error loading backup wallet " + TEMP_BACKUP_EXTENSION, e);
-            }
         }
 
-        return new WalletBackupAndKey(walletAndKey.wallet, backupAndKey.wallet, walletAndKey.key);
+        return backupWallets.isEmpty() ? null : backupWallets.values().iterator().next();
     }
 
-    public WalletAndKey loadWallet(File encryptedFile, CharSequence password) throws IOException, StorageException {
+    public void saveWallet(Wallet wallet) throws IOException {
-        InputStream fileStream = new FileInputStream(encryptedFile);
-        ECKey encryptionKey = getEncryptionKey(password, fileStream);
-
-        InputStream inputStream = new InflaterInputStream(new ECIESInputStream(fileStream, encryptionKey, getEncryptionMagic()));
-        Reader reader = new InputStreamReader(inputStream, StandardCharsets.UTF_8);
-        Wallet wallet = gson.fromJson(reader, Wallet.class);
-        reader.close();
-
-        Key key = new Key(encryptionKey.getPrivKeyBytes(), keyDeriver.getSalt(), EncryptionType.Deriver.ARGON2);
-
-        encryptionPubKey = ECKey.fromPublicOnly(encryptionKey);
-        return new WalletAndKey(wallet, key);
-    }
-
-    public void storeWallet(Wallet wallet) throws IOException {
         if(encryptionPubKey != null && !NO_PASSWORD_KEY.equals(encryptionPubKey)) {
-            storeWallet(encryptionPubKey, wallet);
+            walletFile = persistence.storeWallet(walletFile, wallet, encryptionPubKey);
             return;
         }
 
-        File parent = walletFile.getParentFile();
+        walletFile = persistence.storeWallet(walletFile, wallet);
-        if(!parent.exists() && !createOwnerOnlyDirectory(parent)) {
-            throw new IOException("Could not create folder " + parent);
-        }
-
-        if(!walletFile.getName().endsWith(".json")) {
-            File jsonFile = new File(parent, walletFile.getName() + ".json");
-            if(walletFile.exists()) {
-                if(!walletFile.renameTo(jsonFile)) {
-                    throw new IOException("Could not rename " + walletFile.getName() + " to " + jsonFile.getName());
-                }
-            }
-            walletFile = jsonFile;
-        }
-
-        if(!walletFile.exists()) {
-            createOwnerOnlyFile(walletFile);
-        }
-
-        Writer writer = new FileWriter(walletFile);
-        gson.toJson(wallet, writer);
-        writer.close();
-    }
-
-    private void storeWallet(ECKey encryptionPubKey, Wallet wallet) throws IOException {
-        File parent = walletFile.getParentFile();
-        if(!parent.exists() && !createOwnerOnlyDirectory(parent)) {
-            throw new IOException("Could not create folder " + parent);
-        }
-
-        if(walletFile.getName().endsWith(".json")) {
-            File noJsonFile = new File(parent, walletFile.getName().substring(0, walletFile.getName().lastIndexOf('.')));
-            if(walletFile.exists()) {
-                if(!walletFile.renameTo(noJsonFile)) {
-                    throw new IOException("Could not rename " + walletFile.getName() + " to " + noJsonFile.getName());
-                }
-            }
-            walletFile = noJsonFile;
-        }
-
-        if(!walletFile.exists()) {
-            createOwnerOnlyFile(walletFile);
-        }
-
-        OutputStream outputStream = new FileOutputStream(walletFile);
-        writeBinaryHeader(outputStream);
-
-        OutputStreamWriter writer = new OutputStreamWriter(new DeflaterOutputStream(new ECIESOutputStream(outputStream, encryptionPubKey, getEncryptionMagic())), StandardCharsets.UTF_8);
-        gson.toJson(wallet, writer);
-        writer.close();
-    }
-
-    private void writeBinaryHeader(OutputStream outputStream) throws IOException {
-        ByteBuffer buf = ByteBuffer.allocate(21);
-        buf.put(HEADER_MAGIC_1.getBytes(StandardCharsets.UTF_8));
-        buf.put(keyDeriver.getSalt());
-
-        byte[] encoded = Base64.getEncoder().encode(buf.array());
-        if(encoded.length != BINARY_HEADER_LENGTH) {
-            throw new IllegalStateException("Header length not " + BINARY_HEADER_LENGTH + " bytes");
-        }
-        outputStream.write(encoded);
     }
 
     public void backupWallet() throws IOException {
@@ -232,7 +106,7 @@ public class Storage {
         }
     }
 
-    public void backupWallet(String extension) throws IOException {
+    private void backupWallet(String extension) throws IOException {
         File backupDir = getWalletsBackupDir();
 
         Date backupDate = new Date();
@@ -260,7 +134,11 @@ public class Storage {
         deleteBackups(null);
     }
 
-    public void deleteBackups(String extension) {
+    public void deleteTempBackups() {
+        deleteBackups(Storage.TEMP_BACKUP_EXTENSION);
+    }
+
+    private void deleteBackups(String extension) {
         File[] backups = getBackups(extension);
         for(File backup : backups) {
             backup.delete();
@@ -280,6 +158,7 @@ public class Storage {
                     (notExtension == null || !name.endsWith("." + notExtension));
         });
 
+        backups = backups == null ? new File[0] : backups;
         Arrays.sort(backups, Comparator.comparing(o -> getBackupDate(((File)o).getName())).reversed());
 
         return backups;
@@ -303,78 +182,45 @@ public class Storage {
     }
 
     public ECKey getEncryptionKey(CharSequence password) throws IOException, StorageException {
-        return getEncryptionKey(password, null);
+        return persistence.getEncryptionKey(password);
-    }
-
-    private ECKey getEncryptionKey(CharSequence password, InputStream inputStream) throws IOException, StorageException {
-        if(password.equals("")) {
-            return NO_PASSWORD_KEY;
-        }
-
-        return getKeyDeriver(inputStream).deriveECKey(password);
     }
 
     public AsymmetricKeyDeriver getKeyDeriver() {
-        return keyDeriver;
+        return persistence.getKeyDeriver();
     }
 
     void setKeyDeriver(AsymmetricKeyDeriver keyDeriver) {
-        this.keyDeriver = keyDeriver;
+        persistence.setKeyDeriver(keyDeriver);
-    }
-
-    private AsymmetricKeyDeriver getKeyDeriver(InputStream inputStream) throws IOException, StorageException {
-        if(keyDeriver == null) {
-            byte[] salt = new byte[SPRW1_PARAMETERS.saltLength];
-
-            if(inputStream != null) {
-                byte[] header = new byte[BINARY_HEADER_LENGTH];
-                int read = inputStream.read(header);
-                if(read != BINARY_HEADER_LENGTH) {
-                    throw new StorageException("Not a Sparrow wallet - invalid header");
-                }
-                try {
-                    byte[] decodedHeader = Base64.getDecoder().decode(header);
-                    byte[] magic = Arrays.copyOfRange(decodedHeader, 0, HEADER_MAGIC_1.length());
-                    if(!HEADER_MAGIC_1.equals(new String(magic, StandardCharsets.UTF_8))) {
-                        throw new StorageException("Not a Sparrow wallet - invalid magic");
-                    }
-                    salt = Arrays.copyOfRange(decodedHeader, HEADER_MAGIC_1.length(), decodedHeader.length);
-                } catch(IllegalArgumentException e) {
-                    throw new StorageException("Not a Sparrow wallet - invalid header");
-                }
-            } else {
-                SecureRandom secureRandom = new SecureRandom();
-                secureRandom.nextBytes(salt);
-            }
-
-            keyDeriver = new Argon2KeyDeriver(salt);
-        } else if(inputStream != null) {
-            inputStream.skip(BINARY_HEADER_LENGTH);
-        }
-
-        return keyDeriver;
-    }
-
-    private static byte[] getEncryptionMagic() {
-        return "BIE1".getBytes(StandardCharsets.UTF_8);
     }
 
     public static boolean walletExists(String walletName) {
         File encrypted = new File(getWalletsDir(), walletName.trim());
-        File unencrypted = new File(getWalletsDir(), walletName.trim() + ".json");
+        if(encrypted.exists()) {
+            return true;
+        }
 
-        return (encrypted.exists() || unencrypted.exists());
+        for(PersistenceType persistenceType : PersistenceType.values()) {
+            File unencrypted = new File(getWalletsDir(), walletName.trim() + "." + persistenceType.getExtension());
+            if(unencrypted.exists()) {
+                return true;
+            }
+        }
+
+        return false;
     }
 
     public static File getExistingWallet(String walletName) {
-        File encrypted = new File(getWalletsDir(), walletName);
+        File encrypted = new File(getWalletsDir(), walletName.trim());
-        File unencrypted = new File(getWalletsDir(), walletName + ".json");
-
         if(encrypted.exists()) {
             return encrypted;
-        } else if(unencrypted.exists()) {
+        }
+
+        for(PersistenceType persistenceType : PersistenceType.values()) {
+            File unencrypted = new File(getWalletsDir(), walletName.trim() + "." + persistenceType.getExtension());
+            if(unencrypted.exists()) {
                 return unencrypted;
             }
+        }
 
         return null;
     }
@@ -468,7 +314,7 @@ public class Storage {
         return new File(System.getProperty("user.home"));
     }
 
-    private static boolean createOwnerOnlyDirectory(File directory) {
+    public static boolean createOwnerOnlyDirectory(File directory) {
         try {
             if(Platform.getCurrent() == Platform.WINDOWS) {
                 Files.createDirectories(directory.toPath());
@@ -519,162 +365,6 @@ public class Storage {
         return ownerOnly;
     }
 
-    private static class ExtendedPublicKeySerializer implements JsonSerializer<ExtendedKey> {
-        @Override
-        public JsonElement serialize(ExtendedKey src, Type typeOfSrc, JsonSerializationContext context) {
-            return new JsonPrimitive(src.toString());
-        }
-    }
-
-    private static class ExtendedPublicKeyDeserializer implements JsonDeserializer<ExtendedKey> {
-        @Override
-        public ExtendedKey deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
-            return ExtendedKey.fromDescriptor(json.getAsJsonPrimitive().getAsString());
-        }
-    }
-
-    private static class ByteArraySerializer implements JsonSerializer<byte[]> {
-        @Override
-        public JsonElement serialize(byte[] src, Type typeOfSrc, JsonSerializationContext context) {
-            return new JsonPrimitive(Utils.bytesToHex(src));
-        }
-    }
-
-    private static class ByteArrayDeserializer implements JsonDeserializer<byte[]> {
-        @Override
-        public byte[] deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
-            return Utils.hexToBytes(json.getAsJsonPrimitive().getAsString());
-        }
-    }
-
-    private static class Sha256HashSerializer implements JsonSerializer<Sha256Hash> {
-        @Override
-        public JsonElement serialize(Sha256Hash src, Type typeOfSrc, JsonSerializationContext context) {
-            return new JsonPrimitive(src.toString());
-        }
-    }
-
-    private static class Sha256HashDeserializer implements JsonDeserializer<Sha256Hash> {
-        @Override
-        public Sha256Hash deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
-            return Sha256Hash.wrap(json.getAsJsonPrimitive().getAsString());
-        }
-    }
-
-    private static class DateSerializer implements JsonSerializer<Date> {
-        @Override
-        public JsonElement serialize(Date src, Type typeOfSrc, JsonSerializationContext context) {
-            return new JsonPrimitive(src.getTime());
-        }
-    }
-
-    private static class DateDeserializer implements JsonDeserializer<Date> {
-        @Override
-        public Date deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
-            return new Date(json.getAsJsonPrimitive().getAsLong());
-        }
-    }
-
-    private static class TransactionSerializer implements JsonSerializer<Transaction> {
-        @Override
-        public JsonElement serialize(Transaction src, Type typeOfSrc, JsonSerializationContext context) {
-            try {
-                ByteArrayOutputStream baos = new ByteArrayOutputStream();
-                src.bitcoinSerializeToStream(baos);
-                return new JsonPrimitive(Utils.bytesToHex(baos.toByteArray()));
-            } catch (IOException e) {
-                throw new IllegalStateException(e);
-            }
-        }
-    }
-
-    private static class TransactionDeserializer implements JsonDeserializer<Transaction> {
-        @Override
-        public Transaction deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
-            byte[] rawTx = Utils.hexToBytes(json.getAsJsonPrimitive().getAsString());
-            return new Transaction(rawTx);
-        }
-    }
-
-    private static class KeystoreSerializer implements JsonSerializer<Keystore> {
-        @Override
-        public JsonElement serialize(Keystore keystore, Type typeOfSrc, JsonSerializationContext context) {
-            JsonObject jsonObject = (JsonObject)getGson(false).toJsonTree(keystore);
-            if(keystore.hasPrivateKey()) {
-                jsonObject.remove("extendedPublicKey");
-                jsonObject.getAsJsonObject("keyDerivation").remove("masterFingerprint");
-            }
-
-            return jsonObject;
-        }
-    }
-
-    private static class NodeSerializer implements JsonSerializer<WalletNode> {
-        @Override
-        public JsonElement serialize(WalletNode node, Type typeOfSrc, JsonSerializationContext context) {
-            JsonObject jsonObject = (JsonObject)getGson(false).toJsonTree(node);
-
-            JsonArray children = jsonObject.getAsJsonArray("children");
-            Iterator<JsonElement> iter = children.iterator();
-            while(iter.hasNext()) {
-                JsonObject childObject = (JsonObject)iter.next();
-                removeEmptyCollection(childObject, "children");
-                removeEmptyCollection(childObject, "transactionOutputs");
-
-                if(childObject.get("label") == null && childObject.get("children") == null && childObject.get("transactionOutputs") == null) {
-                    iter.remove();
-                }
-            }
-
-            return jsonObject;
-        }
-
-        private void removeEmptyCollection(JsonObject jsonObject, String memberName) {
-            if(jsonObject.get(memberName) != null && jsonObject.getAsJsonArray(memberName).size() == 0) {
-                jsonObject.remove(memberName);
-            }
-        }
-    }
-
-    private static class NodeDeserializer implements JsonDeserializer<WalletNode> {
-        @Override
-        public WalletNode deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
-            WalletNode node = getGson(false).fromJson(json, typeOfT);
-            node.parseDerivation();
-
-            for(WalletNode childNode : node.getChildren()) {
-                childNode.parseDerivation();
-                if(childNode.getChildren() == null) {
-                    childNode.setChildren(new TreeSet<>());
-                }
-                if(childNode.getTransactionOutputs() == null) {
-                    childNode.setTransactionOutputs(new TreeSet<>());
-                }
-            }
-
-            return node;
-        }
-    }
-
-    public static class WalletAndKey {
-        public final Wallet wallet;
-        public final Key key;
-
-        public WalletAndKey(Wallet wallet, Key key) {
-            this.wallet = wallet;
-            this.key = key;
-        }
-    }
-
-    public static class WalletBackupAndKey extends WalletAndKey {
-        public final Wallet backupWallet;
-
-        public WalletBackupAndKey(Wallet wallet, Wallet backupWallet, Key key) {
-            super(wallet, key);
-            this.backupWallet = backupWallet;
-        }
-    }
-
     public static class LoadWalletService extends Service<WalletBackupAndKey> {
         private final Storage storage;
         private final SecureString password;
@@ -688,7 +378,7 @@ public class Storage {
         protected Task<WalletBackupAndKey> createTask() {
             return new Task<>() {
                 protected WalletBackupAndKey call() throws IOException, StorageException {
-                    WalletBackupAndKey walletBackupAndKey = storage.loadWallet(password);
+                    WalletBackupAndKey walletBackupAndKey = storage.loadEncryptedWallet(password);
                     password.clear();
                     return walletBackupAndKey;
                 }

src/main/java/com/sparrowwallet/sparrow/io/WalletBackupAndKey.java

@@ -0,0 +1,51 @@
+package com.sparrowwallet.sparrow.io;
+
+import com.sparrowwallet.drongo.crypto.*;
+import com.sparrowwallet.drongo.wallet.Wallet;
+
+import java.util.Map;
+
+public class WalletBackupAndKey {
+    private final Wallet wallet;
+    private final Wallet backupWallet;
+    private final ECKey encryptionKey;
+    private final Key key;
+    private final Map<Storage, WalletBackupAndKey> childWallets;
+
+    public WalletBackupAndKey(Wallet wallet, Wallet backupWallet, ECKey encryptionKey, AsymmetricKeyDeriver keyDeriver, Map<Storage, WalletBackupAndKey> childWallets) {
+        this.wallet = wallet;
+        this.backupWallet = backupWallet;
+        this.encryptionKey = encryptionKey;
+        this.key = encryptionKey == null ? null : new Key(encryptionKey.getPrivKeyBytes(), keyDeriver.getSalt(), EncryptionType.Deriver.ARGON2);
+        this.childWallets = childWallets;
+    }
+
+    public Wallet getWallet() {
+        return wallet;
+    }
+
+    public Wallet getBackupWallet() {
+        return backupWallet;
+    }
+
+    public ECKey getEncryptionKey() {
+        return encryptionKey;
+    }
+
+    public Key getKey() {
+        return key;
+    }
+
+    public Map<Storage, WalletBackupAndKey> getChildWallets() {
+        return childWallets;
+    }
+
+    public void clear() {
+        if(encryptionKey != null) {
+            encryptionKey.clear();
+        }
+        if(key != null) {
+            key.clear();
+        }
+    }
+}

src/main/java/com/sparrowwallet/sparrow/wallet/WalletForm.java

@@ -71,7 +71,7 @@ public class WalletForm {
     }
 
     public void save() throws IOException {
-        storage.storeWallet(wallet);
+        storage.saveWallet(wallet);
     }
 
     public void saveAndRefresh() throws IOException {
@@ -145,7 +145,7 @@ public class WalletForm {
             }
         }
 
-        storage.deleteBackups(Storage.TEMP_BACKUP_EXTENSION);
+        storage.deleteTempBackups();
         return changed;
     }
 

src/test/java/com/sparrowwallet/sparrow/io/StorageTest.java

@@ -1,5 +1,6 @@
 package com.sparrowwallet.sparrow.io;
 
+import com.sparrowwallet.drongo.KeyPurpose;
 import com.sparrowwallet.drongo.Utils;
 import com.sparrowwallet.drongo.policy.PolicyType;
 import com.sparrowwallet.drongo.protocol.ScriptType;
@@ -15,17 +16,17 @@ public class StorageTest extends IoTest {
     @Test
     public void loadWallet() throws IOException, MnemonicException, StorageException {
         Storage storage = new Storage(getFile("sparrow-single-wallet"));
-        Wallet wallet = storage.loadWallet("pass").wallet;
+        Wallet wallet = storage.loadEncryptedWallet("pass").getWallet();
         Assert.assertTrue(wallet.isValid());
     }
 
     @Test
     public void loadSeedWallet() throws IOException, MnemonicException, StorageException {
         Storage storage = new Storage(getFile("sparrow-single-seed-wallet"));
-        Storage.WalletAndKey walletAndKey = storage.loadWallet("pass");
+        WalletBackupAndKey walletAndKey = storage.loadEncryptedWallet("pass");
-        Wallet wallet = walletAndKey.wallet;
+        Wallet wallet = walletAndKey.getWallet();
         Wallet copy = wallet.copy();
-        copy.decrypt(walletAndKey.key);
+        copy.decrypt(walletAndKey.getKey());
 
         for(int i = 0; i < wallet.getKeystores().size(); i++) {
             Keystore keystore = wallet.getKeystores().get(i);
@@ -51,12 +52,20 @@ public class StorageTest extends IoTest {
         Assert.assertEquals("xpub6BrhGFTWPd3DXo8s2BPxHHzCmBCyj8QvamcEUaq8EDwnwXpvvcU9LzpJqENHcqHkqwTn2vPhynGVoEqj3PAB3NxnYZrvCsSfoCniJKaggdy", wallet.getKeystores().get(0).getExtendedPublicKey().toString());
         Assert.assertEquals("af6ebd81714c301c3a71fe11a7a9c99ccef4b33d4b36582220767bfa92768a2aa040f88b015b2465f8075a8b9dbf892a7d6e6c49932109f2cbc05ba0bd7f355fbcc34c237f71be5fb4dd7f8184e44cb0", Utils.bytesToHex(wallet.getKeystores().get(0).getSeed().getEncryptedData().getEncryptedBytes()));
         Assert.assertNull(wallet.getKeystores().get(0).getSeed().getMnemonicCode());
+        Assert.assertEquals("bc1q2mkrttcuzryrdyn9vtu3nfnt3jlngwn476ktus", wallet.getAddress(wallet.getFreshNode(KeyPurpose.RECEIVE)).toString());
+    }
+
+    @Test
+    public void multipleLoadTest() throws IOException, MnemonicException, StorageException {
+        for(int i = 0; i < 100; i++) {
+            loadSeedWallet();
+        }
     }
 
     @Test
     public void saveWallet() throws IOException, MnemonicException, StorageException {
         Storage storage = new Storage(getFile("sparrow-single-wallet"));
-        Wallet wallet = storage.loadWallet("pass").wallet;
+        Wallet wallet = storage.loadEncryptedWallet("pass").getWallet();
         Assert.assertTrue(wallet.isValid());
 
         File tempWallet = File.createTempFile("sparrow", "tmp");
@@ -65,10 +74,10 @@ public class StorageTest extends IoTest {
         Storage tempStorage = new Storage(tempWallet);
         tempStorage.setKeyDeriver(storage.getKeyDeriver());
         tempStorage.setEncryptionPubKey(storage.getEncryptionPubKey());
-        tempStorage.storeWallet(wallet);
+        tempStorage.saveWallet(wallet);
 
         Storage temp2Storage = new Storage(tempWallet);
-        wallet = temp2Storage.loadWallet("pass").wallet;
+        wallet = temp2Storage.loadEncryptedWallet("pass").getWallet();
         Assert.assertTrue(wallet.isValid());
     }
 }