@Override
    public void setKey(String key)
    {
        if (key == null) { 
            cipherKey = null; 
            return;
        }
        byte [] bytes = key.getBytes(StandardCharsets.UTF_8);
        setKey(editKey(bytes));
    }
Set the encryption key. This will apply the user-defined key,
truncated or filled (via the default key) as needed  to meet
the key length specifications.

@param key The encryption key
xmppserver/src/main/java/org/jivesoftware/util/AesEncryptor.java