3 Keypad Thief Modern touchscreen computing devices (e.g., tablet computer) may allow one to set up a lock code. In order to unlock a screen, one needs to enter the correct lock code to the on-screen keypad. This problem is about how hard it is to guess the lock code in a brute force attack. Suppose the lock code has n digits. 1. What is the big-O complexity of a brute force attack? Briefly justify your solution. 2. The lock code is typically 4-digit long, which is much shorter and simpler than strong passwords (for logging into web accounts). Think about why this is the case. Use bullets to itemize the differences between tablet authentication and web authentication (e.g., in security goal, attack model, etc).