chuanqi/cq2_sdk/scripts/decrypt_client_lua.py

"""Self-contained cocos2d-x XXTEA Lua decryptor.

File format (per cocos2d-x xxtea.c + cq2-00 docs):
  [8-byte sign "4meJnPyl"] [XXTEA ciphertext of zlib-compressed lua source]

Key: "34UFXMgtkz" padded to 16 bytes with NULs.
Decrypt flow (mirrors cocos exactly):
  1. ciphertext bytes -> uint32 LE array (no length append)
  2. standard XXTEA decrypt (delta=0x9E3779B9, rounds=6+52//n)
  3. last uint32 = real plaintext length -> truncate
  4. zlib decompress

Usage:
  uv run python scripts/decrypt_client_lua.py            # decrypts key proxies
  uv run python scripts/decrypt_client_lua.py ALL       # decrypt whole stab tree
"""
import struct
import sys
import zlib
from pathlib import Path

SIGN = b"4meJnPyl"
KEY = b"34UFXMgtkz".ljust(16, b"\0")
DELTA = 0x9E3779B9

STAB = Path(r"D:\ProgramFiles\996box\GameBoxDownload\1\cq\cache_206923\mod_fgcq\stab\scripts")
OUT = Path("lua-dec2")


def xxtea_decrypt(v: list[int], key: list[int]) -> list[int]:
    n = len(v)
    if n < 2:
        return v  # cocos: n<1 returns; n==1 unchanged by loop below effectively
    rounds = 6 + 52 // n
    total = (rounds * DELTA) & 0xFFFFFFFF
    y = v[0]
    while total != 0:
        e = (total >> 2) & 3
        for p in range(n - 1, 0, -1):
            z = v[p - 1]
            mx = (((z >> 5) ^ ((y << 2) & 0xFFFFFFFF)) + ((y >> 3) ^ ((z << 4) & 0xFFFFFFFF))) ^ ((total ^ y) + (key[(p & 3) ^ e] ^ z))
            mx &= 0xFFFFFFFF
            y = v[p] = (v[p] - mx) & 0xFFFFFFFF
        z = v[n - 1]
        mx = (((z >> 5) ^ ((y << 2) & 0xFFFFFFFF)) + ((y >> 3) ^ ((z << 4) & 0xFFFFFFFF))) ^ ((total ^ y) + (key[0 ^ e] ^ z))
        mx &= 0xFFFFFFFF
        y = v[0] = (v[0] - mx) & 0xFFFFFFFF
        total = (total - DELTA) & 0xFFFFFFFF
    return v


def bytes_to_u32(data: bytes, include_length: bool) -> list[int]:
    # cocos xxtea_to_uint_array: pad tail bytes into last u32 by OR (no truncation)
    n = (len(data) >> 2) + (0 if (len(data) & 3) == 0 else 1)
    v = [0] * n
    for i in range(len(data)):
        v[i >> 2] |= data[i] << ((i & 3) << 3)
    if include_length:
        v.append(len(data))
    return v


def u32_to_bytes(v: list[int]) -> bytes:
    return struct.pack(f"<{len(v)}I", *v)


def cocos_decrypt(raw: bytes) -> bytes:
    if raw[:8] != SIGN:
        raise ValueError(f"bad sign {raw[:8]!r}")
    cipher = raw[8:]
    v = bytes_to_u32(cipher, include_length=False)
    key = bytes_to_u32(KEY, include_length=False)
    v = xxtea_decrypt(v, key)
    real_len = v[-1]
    if real_len <= 0 or real_len > (len(v) - 1) * 4:
        raise ValueError(f"implausible length {real_len}")
    plain = u32_to_bytes(v[:-1])[:real_len]
    # This game's scripts are stored as plain Lua text (no zlib layer).
    # But tolerate both: if it starts with zlib magic, decompress.
    if plain[:2] == b"\x78\x9c" or plain[:2] == b"\x78\x01" or plain[:2] == b"\x78\xda":
        plain = zlib.decompress(plain)
    return plain


def decrypt_file(src: Path, dst: Path) -> bool:
    try:
        plain = cocos_decrypt(src.read_bytes())
        dst.parent.mkdir(parents=True, exist_ok=True)
        dst.write_bytes(plain)
        return True
    except Exception as e:
        print(f"  FAIL {src.name}: {type(e).__name__}: {e}")
        return False


def main() -> int:
    mode = sys.argv[1] if len(sys.argv) > 1 else "KEY"

    if mode.upper() == "ALL":
        files = list(STAB.rglob("*.lua"))
        out_root = OUT / "stab"
        ok = 0
        for i, f in enumerate(files):
            rel = f.relative_to(STAB)
            if decrypt_file(f, out_root / rel):
                ok += 1
            if i % 200 == 0:
                print(f"  {i}/{len(files)}...")
        print(f"decrypted {ok}/{len(files)} -> {out_root}")
    else:
        targets = [
            "game/proxy/remote/AuthProxy.lua",
            "game/proxy/remote/LoginOtpPassWordProxy.lua",
            "game/proxy/remote/LoginProxy.lua",
            "game/proxy/remote/RemoteProxy.lua",
            "network/networkUtil.lua",
            "game/proxy/GameEnvironmentProxy.lua",
        ]
        for t in targets:
            src = STAB / t
            if not src.exists():
                print(f"  missing: {t}")
                continue
            dst = OUT / t
            if decrypt_file(src, dst):
                print(f"  OK: {t} -> {dst} ({dst.stat().st_size}B)")
    return 0


if __name__ == "__main__":
    sys.exit(main())