def num_to_bytes(num: int):
    """数字转换为4位字节数组(10进制转256进制)"""
    b1 = num // 16777216
    num = num % 16777216
    b2 = num // 65536
    num = num % 65536
    b3 = num // 256
    b4 = num % 256
    return bytes((b1, b2, b3, b4))
