CryptoKey in Godot – Complete Guide

Are you ready to unlock the potential of cryptographic keys in your Godot 4 game development? If you’ve ever wondered about securing your game’s data or implementing authentication, you’re about to step into the world of cryptography within the Godot engine. Understanding the CryptoKey class is a fundamental part of this journey. Through this tutorial, we’ll explore what a cryptographic key is, why it’s significant in the realm of game development, and how you can use it to safeguard your games.

What exactly is CryptoKey, and why is it integral to certain aspects of your game creation process? Let’s delve into the details and discover the power of securing your game’s data with this remarkable tool.

What is CryptoKey?

CryptoKey in Godot is akin to a digital lock and key system — a component used for securing digital content. Think of this: In your virtual world, you may want to pass sensitive information securely between different parts of the game or verify a player’s identity. This is where CryptoKey steps in.

What is it for?

This valuable class is used for tasks such as encryption and decryption, signing data, and securely transmitting information. These abilities are crucial for a variety of features, from in-game purchases to multiplayer functionality.

Why Should I Learn It?

Grasping how to use CryptoKey can be a gamechanger for developers. It’s not just about security; it’s about giving players peace of mind, ensuring fair play, and keeping the game’s backend interactions in a safe, controlled environment. If you’re envisioning a game that involves user data or secure transactions, CryptoKey is an essential piece of the puzzle.

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Generating a New CryptoKey

To secure your game’s data, you first need to generate a cryptographic key. This newly generated key will serve as the basis for your encryption and decryption processes. Here’s how to create a new key in Godot:

var crypto = Crypto.new()
var key = CryptoKey.new()
key.generate(RSA, 2048)  # RSA with 2048 bits is widely used and secure

When you invoke `generate()`, you specify the RSA algorithm and the size of the key in bits. The size of the key affects security and performance — larger keys are more secure but take longer to generate and process.

Storing and Loading Keys

Once you have a key, you must store it securely. You can save it to a file with the following code:

key.save("user://private_key.pem")

This saves the private key to the user’s data directory. To load a key you have previously saved, use:

var loaded_key = CryptoKey.new()
if loaded_key.load("user://private_key.pem"):
    print("Key loaded successfully!")
else:
    print("Failed to load key.")

Loading the key allows you to use it later for encryption, decryption, or verifying signatures without regenerating it each time.

Encrypting and Decrypting Data

With a CryptoKey, you can encrypt sensitive information. Below we’ll encrypt a simple string and then decrypt it.

Firstly, we need to prepare the data for encryption by converting it into a `PoolByteArray`:

var raw_data = "Secret message"
var data_to_encrypt = raw_data.to_utf8()

Now, encrypt the data using a previously set up Crypto object:

var encrypted_data = PoolByteArray()
if crypto.encrypt(encrypted_data, data_to_encrypt, key):
    print("Data encrypted successfully!")

Decryption is just as straightforward. Assuming the `encrypted_data` contains our encrypted string, we’d do this:

var decrypted_data = PoolByteArray()
if crypto.decrypt(decrypted_data, encrypted_data, key):
    var decrypted_string = decrypted_data.get_string_from_utf8()
    print("Decrypted message: ", decrypted_string)

You have now learned how to encrypt and decrypt a string — a process which can be applied to any data you wish to secure in your Godot game.

Signing Data

Signing data allows you to verify its integrity and source. This is done by generating a signature with a private key that recipients can verify with a public key. Here’s a brief example of signing a message:

var signature = PoolByteArray()
if crypto.sign(signature, data_to_encrypt, key):
    print("Data signed successfully!")

The `sign` method uses the CryptoKey to create a signature that is unique to the data and key. You would then distribute the signature along with your data.

To ensure the integrity and authenticity of signed data, you would verify the signature on the recipient’s end:

var public_key = key.get_public_key()
var is_valid_signature = crypto.verify(signature, data_to_encrypt, public_key) 

if is_valid_signature:
    print("The signature is valid!")
else:
    print("The signature is NOT valid!")

Verifying a signature checks that the data has not been altered and confirms it was indeed signed with the matching private key.

In these examples, we’ve covered the generation, storage, loading, encryption, decryption, and signing of data using Godot’s CryptoKey class. These operations form a solid foundation for securing the data within your game and ensuring secure player interactions.Let’s expand our knowledge on working with CryptoKey in Godot by exploring additional use cases and code examples.

Imagine you’re developing a multiplayer game, and you want to secure the transmission of high scores between the client and the server. You would need to encrypt this data before sending and ensure that the server can decrypt it upon reception.

Here’s how you would encrypt the high score data before sending it to the server:

var score_data = "Player123: 5000"  # The high score to be encrypted
var score_data_bytes = score_data.to_utf8()  # Convert to bytes
var encrypted_score = PoolByteArray()

if crypto.encrypt(encrypted_score, score_data_bytes, key):
    # The encrypted score can now be safely sent to the server
    send_to_server(encrypted_score)

On the server side, upon receiving the encrypted data, you would decrypt it using the corresponding private key:

func receive_from_client(encrypted_score):
    var decrypted_score = PoolByteArray()
    if crypto.decrypt(decrypted_score, encrypted_score, server_private_key):
        var score_string = decrypted_score.get_string_from_utf8()
        print("Decrypted score: ", score_string)
        # Further process the score...

So far, we have focused on securing data, but cryptography can also be used to create unique IDs or tokens that could be necessary, for example, for session management or saving game states. Let’s learn how to generate a random token with Godot’s built-in `RandomNumberGenerator`:

var rng = RandomNumberGenerator.new()
var token = PoolByteArray()
for i in 1..16:  # Generating a 128-bit token
    token.append(rng.randi() % 256)

Once generated, you can use your CryptoKey to encrypt this token:

var encrypted_token = PoolByteArray()
if crypto.encrypt(encrypted_token, token, key):
    # The encrypted token can now be stored or transmitted securely
    print("Token encrypted successfully!")

Data integrity and authenticity aside, you’ll likely need to securely store some player settings or save game states. For this, encryption is essential to prevent tampering. Encrypt your player’s data with a simple function:

func encrypt_save_data(save_data):
    var save_data_bytes = JSON.print(save_data).to_utf8()
    var encrypted_data = PoolByteArray()

    if crypto.encrypt(encrypted_data, save_data_bytes, key):
        return encrypted_data
    else:
        print("Failed to encrypt save data.")
        return PoolByteArray()

Reading this data back is just as crucial, so let’s decrypt it when loaded:

func decrypt_save_data(encrypted_data):
    var decrypted_data = PoolByteArray()

    if crypto.decrypt(decrypted_data, encrypted_data, key):
        var save_data = JSON.parse(decrypted_data.get_string_from_utf8()).result
        return save_data
    else:
        print("Failed to decrypt save data.")
        return null

Lastly, you might encounter a scenario where you need to verify data integrity without needing secrecy. This type of situation is ideal for cryptographic hashing, which creates a fixed-size string from any data. We’ll use Godot’s `Crypto` class to hash a password:

var password = "my_secure_password"
var password_hash = crypto.hash_sha256(password.to_utf8())

print("SHA-256 Hash of the password: ", password_hash.hex_encode())

This `password_hash` can be safely stored or transmitted, as it cannot be reversed to find the original password but can be used to verify that a user’s entered password matches the original.

Through this tutorial, we’ve expanded your cryptographic toolkit within the Godot engine. Not only can you now protect sensitive game data and verify data authenticity and integrity, but you’ve also seen how to securely handle tokens and save states. Adding these levels of security will not only protect your game and its players but also enhance your game’s credibility and professionalism.Cryptography can also facilitate secure communication channels between players in a multiplayer environment. One typical example is the exchange of messages that should remain confidential. Let’s see how one might encrypt a message before sending it to another player:

func send_secure_message(to_player, message):
    var message_bytes = message.to_utf8()
    var encrypted_message = PoolByteArray()

    if crypto.encrypt(encrypted_message, message_bytes, key):
        # Here, 'send_to_player' is a hypothetical function that sends the data
        send_to_player(to_player, encrypted_message)

When the recipient player receives the message, they can decrypt it using a shared key or their private key if asymmetric encryption is used:

func on_message_received(encrypted_message):
    var decrypted_message = PoolByteArray()
    
    if crypto.decrypt(decrypted_message, encrypted_message, player_private_key):
        var plain_message = decrypted_message.get_string_from_utf8()
        print("Received secure message: ", plain_message)

Beyond messaging, let’s consider in-game purchases, where transaction security is paramount. Here’s how to securely send transaction data:

func process_in_game_purchase(item_id, player_id):
    var transaction_data = {"item_id": item_id, "player_id": player_id}
    var transaction_json = JSON.print(transaction_data).to_utf8()
    var encrypted_transaction = PoolByteArray()

    if crypto.encrypt(encrypted_transaction, transaction_json, key):
        # Securely send transaction data to the server
        send_transaction_to_server(encrypted_transaction)

On the server side, the transaction is decrypted, processed, and validated:

func validate_purchase(encrypted_transaction):
    var decrypted_transaction = PoolByteArray()

    if crypto.decrypt(decrypted_transaction, encrypted_transaction, server_private_key):
        var transaction_data = JSON.parse(decrypted_transaction.get_string_from_utf8()).result
        # Validate and process the decrypted transaction data

For leaderboard data, you might not only want to encrypt the data but also ensure the scores have not been tampered with. Here’s an example of how you could sign leaderboard data:

func update_leaderboard(player_id, score):
    var leaderboard_data = {"player_id": player_id, "score": score}
    var leaderboard_json = JSON.print(leaderboard_data).to_utf8()
    var signature = PoolByteArray()

    if crypto.sign(signature, leaderboard_json, key):
        # Append signature to the data
        leaderboard_data["signature"] = signature.hex_encode()
        # Here, 'send_leaderboard_data' is a hypothetical function that would send the data to the server
        send_leaderboard_data(leaderboard_data)

When receiving and validating the leaderboard data on the server, the signature must first be checked:

func receive_leaderboard_data(leaderboard_data):
    var signature = PoolByteArray.hex_decode(leaderboard_data["signature"])
    var original_data_json = JSON.print({
        "player_id": leaderboard_data["player_id"],
        "score": leaderboard_data["score"]
    }).to_utf8()

    if crypto.verify(signature, original_data_json, key.get_public_key()):
        print("Leaderboard data verified successfully!")
        # Further process the verified leaderboard data
    else:
        print("Leaderboard data verification failed. Possible tampering detected.")

Protecting the player’s saved game data on local storage is also a necessity, preventing any possibility of cheating by altering save files. Here’s an example of how you might handle save data encryption:

func save_game(player_data):
    var save_json = JSON.print(player_data).to_utf8()
    var encrypted_save_data = PoolByteArray()

    if crypto.encrypt(encrypted_save_data, save_json, key):
        var save_path = "user://player_save_data.sav"
        var save_file = File.new()
        
        if save_file.open(save_path, File.WRITE) == OK:
            save_file.store_buffer(encrypted_save_data)
            save_file.close()
            print("Game saved securely.")
        else:
            print("Failed to open save file for writing.")

And to load the save data:

func load_game():
    var save_path = "user://player_save_data.sav"
    var save_file = File.new()
    var player_data = {}

    if save_file.open(save_path, File.READ) == OK:
        var encrypted_save_data = save_file.get_buffer(save_file.get_len())
        save_file.close()
        
        var decrypted_save_data = PoolByteArray()
        if crypto.decrypt(decrypted_save_data, encrypted_save_data, key):
            player_data = JSON.parse(decrypted_save_data.get_string_from_utf8()).result
            print("Game loaded successfully.")
        else:
            print("Failed to decrypt save data.")
    else:
        print("Failed to open save file for reading.")

    return player_data

Through these examples, we’ve explored a range of practical implementations involving the CryptoKey class in the Godot engine, improving the security and integrity of your game’s data. Whether you’re adding multiplayer features, securing in-game transactions, or preserving the sanctity of your leaderboards and save files, the concepts and methods presented here will be invaluable for your game development journey.

Continuing Your Game Development Journey

Congratulations on taking steps to enhance your game’s security with CryptoKey in Godot. As you progress in your development journey, remember that this is just the beginning—there are many more adventures and challenges to take on in the vast universe of game creation!

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Conclusion

As we bring this exploration of cryptographic keys in Godot to a close, take pride in the knowledge and skills you’ve acquired. By integrating the CryptoKey class into your game development toolkit, you’ve unlocked a new level of expertise that will help build trust with players and establish a professional foundation for your games. Encryption, decryption, and data integrity are no longer just concepts but tangible tools you wield with confidence.

Remember that as you hone your skills, Zenva Academy is your ally every step of the way. Our **[Godot Game Development Mini-Degree](https://academy.zenva.com/product/godot-game-development-mini-degree/)** is designed to support your continued growth in game development. Excited about what’s next on your journey? Take that enthusiasm and channel it into creating amazing games that stand out for their quality and security. May your passion for learning and game development lead you to create worlds that captivate and inspire!

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