Mega888 bgluares Decryptor

bgluares_decrypt.py

#!/usr/bin/env python3
"""
Mega888 bgluares Decryptor
Decrypts XXTEA-encrypted LuaJIT bytecode files with bgluares header.
Encryption Key: cy4ty9cd
Algorithm: XXTEA
"""

import struct, sys, os

def xxtea_decrypt(data, key):
    """XXTEA decrypt bytes with key bytes."""
    if len(data) < 8:
        return data
    n = len(data) // 4
    if n < 2:
        return data
    data = data[:n*4]
    v = list(struct.unpack(f'<{n}I', data))
    k = list(struct.unpack('<4I', key[:16].ljust(16, b'\x00')))
    DELTA = 0x9E3779B9
    rounds = 6 + 52 // n
    total = (rounds * DELTA) & 0xFFFFFFFF
    y = v[0]
    for _ in range(rounds):
        e = (total >> 2) & 3
        for p in range(n-1, 0, -1):
            z = v[p-1]
            mx = (((z >> 5 ^ y << 2) + (y >> 3 ^ z << 4)) ^ ((total ^ y) + (k[(p & 3) ^ e] ^ z))) & 0xFFFFFFFF
            v[p] = (v[p] - mx) & 0xFFFFFFFF
            y = v[p]
        z = v[n-1]
        mx = (((z >> 5 ^ y << 2) + (y >> 3 ^ z << 4)) ^ ((total ^ y) + (k[0 ^ e] ^ z))) & 0xFFFFFFFF
        v[0] = (v[0] - mx) & 0xFFFFFFFF
        y = v[0]
        total = (total - DELTA) & 0xFFFFFFFF
    return struct.pack(f'<{n}I', *v)

def decrypt_file(input_path, output_path=None, key=b'cy4ty9cd'):
    with open(input_path, 'rb') as f:
        data = f.read()
    if data[:8] != b'bgluares':
        raise ValueError(f"Not a bgluares file: {input_path}")
    payload = data[8:]
    if len(payload) % 4 != 0:
        payload = payload + b'\x00' * (4 - len(payload) % 4)
    decrypted = xxtea_decrypt(payload, key)
    if decrypted[:3] != b'\x1bLJ':
        raise ValueError(f"Decryption failed - not LuaJIT bytecode")
    if output_path is None:
        output_path = input_path + '.dec'
    with open(output_path, 'wb') as f:
        f.write(decrypted)
    return output_path

if __name__ == '__main__':
    if len(sys.argv) < 2:
        print(f"Usage: {sys.argv[0]} <input.luac> [output.luajit]")
        sys.exit(1)
    result = decrypt_file(sys.argv[1], sys.argv[2] if len(sys.argv) > 2 else None)
    print(f"Decrypted: {sys.argv[1]} -> {result}")