A hypothetical video game involves two phases. In the first phase, players negotiate to obtain weapons and resources by sending and receiving documents containing text and images - some of the...

Extracted text: A hypothetical video game involves two phases. In the first phase, players negotiate to obtain weapons and resources by sending and receiving documents containing text and images - some of the documents are large (several megabytes). In the second phase, players move around and fight for resources using the weapons they received earlier. This involves typing keystrokes which are sent to a server and processed in real time. In both phases, data must be processed quickly and kept confidential. It has been decided that the Advanced Encryption Standard (AES) algorithm with 256_bit keys will be used for encryption and decryption. Which mode of operation would be most appropriate for the second phase of the game? Give the full name of the mode, explain your choice, and describe how this mode will be used to encrypt one keystroke.