In this task, we have been given a plaintext message, a ciphertext, and an initialization vector (IV), and our goal is to find the key that was used to encrypt the message. To do this, we can write a program using Java and crypto packages.
One approach to finding the key is to use brute force, where we try all possible keys until we find the one that produces the given ciphertext from the given plaintext and IV. To do this, we can use the Java Crypto Library, which provides a set of classes and methods for encryption and decryption.
Here is an example program that uses the Crypto Library to search for the key: