国gal的程序依旧抽象

import json
from pathlib import Path

from Crypto.Cipher import AES

RPA_ROOT = Path("D:/SteamLibrary/steamapps/common/永恒与星辰与日常/game")
INDEX = Path("index.json")
OUT = Path("out")
KEY = bytes.fromhex("6C392AFB08412531C9727C85DD1F015D41435135BEBFCB3A7663ACB4C5CF6962")


def decrypt(data, iv):
    iv = iv.ljust(16, b"\x00")
    return AES.new(KEY, AES.MODE_CTR, nonce=b"", initial_value=iv).decrypt(data)


idx = json.loads(INDEX.read_text())

for rpa, files in idx:
    rpa_path = RPA_ROOT / rpa
    with rpa_path.open("rb") as f:
        for name, entries in files.items():
            out = OUT / name
            out.parent.mkdir(parents=True, exist_ok=True)
            with out.open("wb") as w:
                for offset, length, iv_hex in entries:
                    f.seek(offset)
                    data = f.read(length)
                    w.write(decrypt(data, bytes.fromhex(iv_hex)))