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Game Files - Encryption and Decryption ​

Although Geometry Dash's install path is usually inside the user's steamapps/common folder (if the game was bought from Steam) the game will actually store all relevant user data inside the AppData/Local directory, in which a new folder will be created under the name of GeometryDash. This folder contains all custom songs that the user has downloaded but it also contains 2 important files, which are CCGameManager.dat and CCLocalLevels.dat; the first one contains all the information regarding the player's in-game stats and preferences while the latter contains the data for the game's user created levels.

On MacOS, saves are placed under ~/Library/Application Support/GeometryDash, and use completely different encoding from Windows one.

However when these files are written to the disk they are encrypted and have to be decrypted before they can be read or modified. Both files share the same process for decryption and encryption.

Decryption ​

Windows ​

Local game files are decrypted in the following order: Apply XOR function with key 0xB (11), then apply B64 decoding, the resulting byte sequence will be a gzip compressed string which needs to be decompressed/inflated.

Simple XOR function differs can be written like this:

Python ​

py
def xor(string: str, key: int) -> str:
	return ("").join(chr(ord(char) ^ key) for char in string)

Programmatically decryption can be implemented like so:

Python ​

py
import base64
import gzip


def decrypt_data(data: str) -> str:
	base64_decoded = base64.urlsafe_b64decode(xor(data, key=11).encode())
	decompressed = gzip.decompress(base64_decoded)
	return decompressed.decode()

MacOS ​

On MacOS, decryption is quite simpler. Saves are encrypted with AES, using ECB mode.

256-bit key for encryption looks like this:

Hexadecimal ​

md
69 70 75 39 54 55 76 35 34 79 76 5d 69 73 46 4d 68 35 40 3b 74 2e 35 77 33 34 45 32 52 79 40 7b

Plaintext ​

ipu9TUv54yv]isFMh5@;t.5w34E2Ry@{

Python ​

py
KEY = (  # python will automatically concatenate two parts
    b"\x69\x70\x75\x39\x54\x55\x76\x35\x34\x79\x76\x5d\x69\x73\x46\x4d"
    b"\x68\x35\x40\x3b\x74\x2e\x35\x77\x33\x34\x45\x32\x52\x79\x40\x7b"
)

Here is how actual decryption would be implemented:

Python ​

py
from Crypto.Cipher import AES


def remove_pad(data: bytes) -> bytes:
    last = data[-1]
    if last < 16:
        data = data[:-last]
    return data


def mac_decrypt(data: bytes) -> str:
    cipher = AES.new(KEY, AES.MODE_ECB)
    return remove_pad(cipher.decrypt(data)).decode()

Encryption ​

Note that you don't actually need to reencrypt the save file in order for the game to accept it.

Windows ​

Encryption is done pretty much the same way but with opposite operations and order. So the sequence for encrypting can be defined as: gzip compress/deflate -> Base64 encode -> XOR using 0xb (11) as a key.

Python ​

py
def encrypt_data(data: str) -> str:
	gzipped = gzip.compress(data.encode())
	base64_encoded = base64.urlsafe_b64encode(gzipped)
	return xor(base64_encoded.decode(), key=11)

MacOS ​

Like on Windows, encryption and decrypion are almost the same:

Python ​

py
from Crypto.Cipher import AES


def add_pad(data: bytes) -> bytes:
    len_r = len(data) % 16
    if len_r:
        to_add = 16 - len_r
        data += to_add.to_bytes(1, "little") * to_add
    return data


def mac_encrypt(data: str) -> bytes:
    cipher = AES.new(KEY, AES.MODE_ECB)
    return cipher.encrypt(add_pad(data.encode()))