EchoCrypt is a program that allows you to encrypt and decrypt messages using a key. The tool takes as input a key and a message, and outputs the encrypted or decrypted message. To encrypt a message, you provide a key and the message you want to encrypt, and the tool will return the encrypted message. To decrypt a message, you provide the same key that was used to encrypt the message and the encrypted message, and the tool will return the original message. The tool uses a simple encryption algorithm to encrypt and decrypt the message, but it is not suitable for secure encryption in real-world applications.