Encrypt/Decrypt game level data

Question

Hi!

I have a level editor in the works and I don't want players to change anything outside the editor and right now I am basically saving it as a txt with a custom file format. So when they open it they can change the game time, level author e.t.c. When it is loaded I create a new object and assign the parameters to it. When I save it is basically file.WriteLine(object stuff);. So how would I encrypt the whole file when it is saved and then decrypt it when it is going to be loaded?

Thanks in advance

Answer 1

Best Answer

Answer by Cherno · Nov 24, 2014 at 10:11 PM

Use a BinaryFormatter to serialize your data to a file that can't be modified without deserializing it again first (which would only happen in your editor's saved/load functions).

Here is an example taken from my own leveleditor's map loading and saving. Game is a class that holds all the data you want to save. Every class that is to be serialized needs to be [System.Serializable]. The Load function takes a string that is just the name of the savegame file that is to be loaded. It assigns the loadedGame variable (you can also make it return it) so other scripts can access it and pull any data they need for loading the level (player hitpoints, for example). Be aware that not every type is serializable. Things that are specific to Unity (GameObject, Transform, Vector3 and such) need to be flagged with [System.NonSerialized] before their variable declaration. This counts for EVERY class that will be used when saving and loading.

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 using System.Runtime.Serialization.Formatters.Binary;
 using System.IO;
 
 public static class SaveLoad {
 
     public static Game loadedGame = new Game();
     public static List<Game> savedGames = new List<Game>();
 
     //it's static so we can call it from anywhere
     public static void Save(Game saveGame) {
         
         BinaryFormatter bf = new BinaryFormatter();
         FileStream file = File.Create ("C:/Savegames/" + saveGame.savegameName + ".sav"); //you can call it anything you want
         bf.Serialize(file, saveGame);
         file.Close();
         Debug.Log("Saved Game: " + saveGame.savegameName);
 
     }    
     
     public static void Load(string gameToLoad) {
         if(File.Exists("C:/Savegames/" + gameToLoad + ".sav")) {
             BinaryFormatter bf = new BinaryFormatter();
             FileStream file = File.Open("C:/Savegames/" + gameToLoad + ".gd", FileMode.Open);
             loadedGame = (Game)bf.Deserialize(file);
             file.Close();
             Debug.Log("Loaded Game: " + loadedGame.savegameName);
         }
     }
 
 
 }

Theoretically, you could just take the string that would be put into the txt file of yours, and store it aas a string variable inside the instance of the Game variable that is used as a savegame.

Add comment · Show 4 · Share

RealMTG · Nov 25, 2014 at 05:48 PM 0

Share

I'll be honest, I don't understand a lot of this. I made a test with this code and I got a weird error.

Code:

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 using System.Runtime.Serialization.Formatters.Binary;
 using System.IO;
 
 [System.Serializable]
 public class EncryptTest : $$anonymous$$onoBehaviour {
 
     string text = "";
 
     void OnGUI () {
         text = GUI.TextArea(new Rect(0, 0, 200, 200), text);
 
         if(GUI.Button(new Rect(0, 200, 100, 30), "Save")){
             Save ();
         }
 
         if(GUI.Button(new Rect(100, 200, 100, 30), "Load")){
             Load ();
         }
     }
 
     public void Save(){
         BinaryFormatter bf = new BinaryFormatter();
         FileStream file = File.Create ("C:/QS/encrypt_test.qslvl");
         bf.Serialize(file, this);
         file.Close();
     }
 
     public void Load(){
         if(File.Exists("C:/QS/encrypt_test.qslvl")){
             BinaryFormatter bf = new BinaryFormatter();
             FileStream file = File.Open("C:/QS/encrypt_test.qslvl", File$$anonymous$$ode.Open);
             text = (string)bf.Deserialize(file);
             file.Close();
         }
     }
 }

Error: SerializationException: Type UnityEngine.$$anonymous$$onoBehaviour in assembly UnityEngine, Version=0.0.0.0, Culture=neutral, Public$$anonymous$$eyToken=null is not marked as serializable.

Could you please help me with this because I honestly don't know what I should do.

Cherno · Nov 25, 2014 at 05:58 PM 0

Share

It looks like you are trying to serialize the very script that calls the serialization functons... I don't know if that's a good idea. Better create a seperate Game class that stores the data and serialize that.

I also think that you can't serialize any classes that inherit form $$anonymous$$onoBehavior, which is why you would need so-called container classes that hold things for, say, a character monobehavior class.

Furthermore, this might be outside of UA's scope so I recommend just doing a google search on C# Serialization and read some tutorials. You won't get it to work in half an hour, I think it took me several days to understand what does what, so you just need to read, test, read, test :)

RealMTG · Nov 25, 2014 at 06:08 PM 0

Share

@Cherno Ah. I see. Well thanks for the code and tips! I will do as you say. :)

Cherno · Nov 25, 2014 at 06:23 PM 0

Share

To test things out, do the following:

Take the script from my answer as-is, and keep it somewhere in your Assets folder.

Create a new Script and also keep it somewhere in your Asset folder:

 using UnityEngine;
 using System.Collections;
 
 [System.Serializable]
 public class Game { //don't need ": $$anonymous$$onobehaviour" because we are not attaching it to a game object
 
     public string savegameName;
     public string testString;
 
         
 }

then, create a simple monoBehavior script for your save and load menu, like you did in your comment above. However, in the save and load GUI buttons, insert the folling code when they are clicked:

Save button:

 Game newSavedGame = new Game();
 newSavedGame.savegameName = "$$anonymous$$ySaveGame";
 newSavedGame.testString = "Hello!";
 SaveLoad.Save(newSavedGame);

Load button:

 SaveLoad.Load("$$anonymous$$ySaveGame");
 Debug.Log(SaveLoad.loadedGame.testString);

Encrypt/Decrypt game level data

1 Reply

Your answer

Welcome to Unity Answers

Follow this Question

Related Questions