fix import of encrypted json wallet on linux

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

@@ -101,9 +101,12 @@ public class Sparrow implements WalletImport, WalletExport {
             java.nio.file.Files.copy(inputStream, tempFile.toPath(), StandardCopyOption.REPLACE_EXISTING);
             PersistenceType persistenceType = Storage.detectPersistenceType(tempFile);
             persistenceType = (persistenceType == null ? PersistenceType.JSON : persistenceType);
-            File tempTypedFile = new File(tempFile.getParentFile(), tempFile.getName() + "." + persistenceType.getExtension());
-            tempFile.renameTo(tempTypedFile);
-            tempFile = tempTypedFile;
+            if(persistenceType != PersistenceType.JSON || !isEncrypted(tempFile)) {
+                File tempTypedFile = new File(tempFile.getParentFile(), tempFile.getName() + "." + persistenceType.getExtension());
+                tempFile.renameTo(tempTypedFile);
+                tempFile = tempTypedFile;
+            }
+
             storage = new Storage(persistenceType, tempFile);
             if(!isEncrypted(tempFile)) {
                 wallet = storage.loadUnencryptedWallet().getWallet();

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

@@ -13,6 +13,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.*;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.attribute.PosixFilePermission;
 import java.nio.file.attribute.PosixFilePermissions;
@@ -373,7 +374,7 @@ public class Storage {
     }
 
     public static PersistenceType detectPersistenceType(File walletFile) {
-        try(Reader reader = new FileReader(walletFile)) {
+        try(Reader reader = new FileReader(walletFile, StandardCharsets.UTF_8)) {
             int firstChar = reader.read();
 
             if(firstChar == 'U' || firstChar == '{') {