How to encrypt .img archive?

[pro0xy]

Hello, someone know how to encrypt .img archive? Like gta3.img, so that players can't open it through img tool and pull my models, only the decryption on the client.

[Laxante101]

You can use a strong encryption algorithm like AES. First, choose a programming language, like Python, and use a library that supports encryption, like pycryptodome
You can create a script that reads the file to be encrypted, generates a 16-byte (128-bit) key, and uses CBC mode to encrypt the content. The Python code would look like this:

 

from Crypto.Cipher import AES
from Crypto.Util.Padding import pad
import os

def encrypt_file(file_name, key):
    cipher = AES.new(key, AES.MODE_CBC)
    iv = cipher.iv
    with open(file_name, 'rb') as f:
        plaintext = f.read()
    ciphertext = iv + cipher.encrypt(pad(plaintext, AES.block_size))
    with open(file_name + '.enc', 'wb') as f:
        f.write(ciphertext)

key = os.urandom(16)
encrypt_file('gta3.img', key)

Use programs like Visual Code Studio to better handle it.

Then, on the client, you need to implement decryption. This involves reading the encrypted file, extracting the initialization vector (IV), and decrypting the contents with the same key that was used for encryption. The code for decryption would look like this:

 

from Crypto.Cipher import AES
from Crypto.Util.Padding import unpad

def decrypt_file(file_name, key):
    with open(file_name, 'rb') as f:
        iv = f.read(16)
        ciphertext = f.read()
    cipher = AES.new(key, AES.MODE_CBC, iv)
    plaintext = unpad(cipher.decrypt(ciphertext), AES.block_size)
    with open('gta3_decrypted.img', 'wb') as f:
        f.write(plaintext)

decrypt_file('gta3.img.enc', key)

Make sure to store the key securely on the client, as it is required for decryption if needed. Once you have implemented encryption and decryption, test the client to ensure that it can access the models without issues.