Pixel Game Maker MV 引擎资源解密脚本

pgmm-codec.py

import os
import click
import struct
import json
from base64 import b64decode
from twofish import Twofish

iv = bytes.fromhex("A0 47 E9 3D 23 0A 4C 62 A7 44 B1 A4 EE 85 7F BA")


def rotr32(x, n):
    return (x >> n) | ((x << (32 - n)) & 0xFFFFFFFF)

def rotl32(x, n):
    return ((x << n) & 0xFFFFFFFF) | (x >> (32 - n))

def bytesToWords(data: bytes) -> list[int]:
    assert len(data) % 4 == 0

    words = []
    for i in range(len(data)//4):
        words.append(struct.unpack("<L", data[i*4:i*4+4])[0])
    return words

def wordsToBytes(words: list[int]) -> bytes:
    buf = bytearray()
    for word in words:
        buf.extend(struct.pack("<L", word))
    return bytes(buf)

def decrypt_key(words: list[int]):
    assert len(words) == 4 # 16bytes

    for _ in range(8):
        words[2] = rotl32(words[2], 1) & 0xffffffff
        words[3] = rotr32(words[3] & 0xffffffff, 1)
        words[0] = rotl32(words[0], 1) & 0xffffffff
        words[1] = rotr32(words[1] & 0xffffffff, 1)

    [words[0], words[2]] = [words[2], words[0]]
    [words[1], words[3]] = [words[3], words[1]]

    return words

def xor(a, b):
    w = [0 for _ in range(len(a))]
    for i in range(len(a)):
        w[i] = a[i] ^ b[i]
    return bytes(w)

def kc(data: bytes, key: bytes):
    key = list(key)
    i = 0
    h = len(data) - data[3] - 4
    while h > 0:
        t = (h ^ key[i]) & 0xff
        key[i] = 1 if t < 1 else t
        h //= 256
        i += 1
    return bytes(key)

def decrypt_file(ipath, opath, key):
    data = open(ipath, "rb").read()
    twofish = Twofish(kc(data, key))

    try:
        file = open(opath, "wb")
    except FileNotFoundError:
        os.mkdir(os.path.dirname(opath))
        file = open(opath, "wb")

    xora = iv

    cnt = (len(data)-4) // 16
    for i in range(cnt):
        ct = data[i*16+4:i*16+20]
        pt = twofish.decrypt(ct)
        file.write(xor(xora, pt))
        xora = ct
    file.close()


@click.group()
def main():
    """\b
    ╔═╗╔═╗╔╦╗╔╦╗  ╔═╗┌─┐┌┬┐┌─┐┌─┐
    ╠═╝║ ╦║║║║║║  ║  │ │ ││├┤ │  
    ╩  ╚═╝╩ ╩╩ ╩  ╚═╝└─┘─┴┘└─┘└─┘
    Pixel Game Maker MV Codec @syrinka

    \b
    使用方法：
    1. get-key 获取游戏密钥
    2. decrypt 解密需要的资源

    pgmm-codec COMMAND --help 查看对应命令的帮助

    \b
    Thanks to:
    https://github.com/blluv/pgmm_decrypt
    """
    pass


@main.command('get-key', short_help='获取游戏的密钥')
@click.argument('info',
    type=click.Path(exists=True, dir_okay=False, readable=True))
def func(info):
    """
    获取游戏的密钥
    
    INFO: 游戏的 info.json 文件路径，该文件通常位于 <游戏根目录/Resources/data> 目录下
    
    \b
    使用例：
        pgmm-codec get-key Resources/data/info.json
    """
    info = json.loads(open(info, "rb").read().decode("utf8"))
    data_words = bytesToWords(b64decode(info["key"]))
    key = xor(iv, wordsToBytes(decrypt_key(data_words)))
    print(f'该游戏密匙为 [{repr(key)[2:-1]}]')
    print('请复制 [ ] 内的部分')


@main.command('decrypt', short_help='使用密钥解密文件')
@click.argument('key')
@click.option('-i', '--input',
    type=click.Path(exists=True, file_okay=False, readable=True),
    required=True,
    help='''\b
    输入目录，将会尝试解密其下的*所有文件*
    请留意当中是否仍有正常文件，解密后很可能打不开''')
@click.option('-o', '--output',
    type=click.Path(file_okay=False),
    help='输出目录，留空则为 <输入目录>-dec')
@click.option('-q', '--quiet',
    is_flag=True)
def func(key, input, output, quiet):
    """
    使用密钥解密资源，并输出到指定路径

    KEY: 通过 get-key 获得的密钥

    \b
    使用例：
        pgmm-codec decrypt KEY -i Resources/img -o img-dec
    """
    scope = {'key': key}
    exec(f'key = b"{key}"', scope)
    key = scope['key']

    if output is None:
        output = input + '-dec'

    ilen = len(input)
    for root, dirs, files in os.walk(input):
        if not quiet:
            print(f'# 当前目录：{root}')

        for file in files:
            ipath = os.path.join(root, file)
            opath = os.path.join(output, root[ilen+1:], file)
            decrypt_file(ipath, opath, key)
            if not quiet:
                print(file)


if __name__ == '__main__':
    main()