chuanqi/cq2_sdk/scripts/decrypt_lua.py

"""Try all XXTEA key/layout variants on the encrypted Lua file."""
import hashlib
import sys
from pathlib import Path

import xxtea

if hasattr(sys.stdout, "reconfigure"):
    sys.stdout.reconfigure(encoding="utf-8", errors="replace")

SRC = Path(r"D:\ProgramFiles\996box\GameBoxDownload\1\cq\cache_206923\mod_fgcq\stab\scripts\network\networkUtil.lua")
raw = SRC.read_bytes()
print(f"file: {len(raw)} bytes, sign={raw[:8]!r}")

cands = {
    "key_null16": b"34UFXMgtkz".ljust(16, b"\0"),
    "key_space16": b"34UFXMgtkz".ljust(16, b" "),
    "key_rep16": (b"34UFXMgtkz" * 2)[:16],
    "key_sign16": (b"34UFXMgtkz" + b"4meJnPyl")[:16],
    "sign16": b"4meJnPyl".ljust(16, b"\0"),
    "md5key16": hashlib.md5(b"34UFXMgtkz").digest(),
    "md5sign16": hashlib.md5(b"4meJnPyl").digest(),
    "sign_key16": (b"4meJnPyl" + b"34UFXMgtkz")[:16],
}

blobs = {
    "after_sign": raw[8:],
    "whole": raw,
    "skip1": raw[9:],
}


def looks_lua(dec: bytes) -> bool:
    if not dec:
        return False
    head = dec[:80].lstrip()
    return head.startswith((b"--", b"local", b"function", b"require", b"return"))


for blob_label, blob in blobs.items():
    for key_label, key in cands.items():
        try:
            dec = xxtea.decrypt(blob, key)
        except Exception:
            continue
        if dec and looks_lua(dec):
            print(f"\n*** SUCCESS: blob={blob_label} key={key_label} -> {len(dec)} bytes")
            print(dec[:600].decode("utf-8", errors="replace"))
            out = Path(f"decrypted_{blob_label}_{key_label}.lua")
            out.write_bytes(dec)
            print(f"\nsaved to {out}")
            sys.exit(0)
        elif dec:
            printable = sum(1 for b in dec[:100] if 32 <= b < 127 or b in (9, 10, 13))
            if printable > 80:
                print(f"\n~ partial? blob={blob_label} key={key_label} printable={printable}%")
                print(dec[:200].decode("latin1"))

print("\nno variant produced valid Lua")