from Crypto.Cipher import AES

def encrypt(data:bytes, key:bytes):
    cipher = AES.new(key, AES.MODE_EAX)
    nonce = cipher.nonce
    ciphertext, mac = cipher.encrypt_and_digest(data)
    return nonce, ciphertext, mac

def decrypt_and_verify(nonce:bytes, data:bytes, mac:bytes, key:bytes):
    cipher = AES.new(key, AES.MODE_EAX, nonce=nonce)
    plaintext = cipher.decrypt(data)
    try:
        cipher.verify(mac)
    except ValueError:
        return None
    return plaintext