import os
from Crypto.Cipher import ChaCha20

def encrypt_message(message, key, nonce):
    cipher = ChaCha20.new(key=key, nonce=nonce)
    ciphertext = cipher.encrypt(message)
    return ciphertext

def chosen_plaintext_attack(ciphertext, key, nonce):
    # Create a dictionary of known plaintexts and their corresponding ciphertexts
    known_plaintexts = {b"Our counter agencies have": b"", b"example2": b""}
    for plaintext in known_plaintexts:
        # Encrypt the known plaintext using the same key and nonce as the original ciphertext
        known_ciphertext = encrypt_message(plaintext, key, nonce)
        # Compare the known ciphertext with the original ciphertext
        if known_ciphertext == ciphertext:
            # If the ciphertexts match, the original plaintext is likely the known plaintext
            return plaintext
    return None

if __name__ == "__main__":
    message = b"Our counter agencies have intercepted your messages and a lot"
    key, nonce = os.urandom(32), os.urandom(12)
    encrypted_message = encrypt_message(message, key, nonce)

    # Perform the chosen plaintext attack
    recovered_message = chosen_plaintext_attack(encrypted_message, key, nonce)
    if recovered_message is not None:
        print("Recovered message:", recovered_message)
    else:
        print("Failed to recover message")