}

    @Override
    public Enumeration<String> engineAliases() {
        return Collections.enumeration(keys.keySet());
    }

    @Override
    public boolean engineContainsAlias(String alias) {
        return keys.containsKey(alias) || certChains.containsKey(alias);
    }

    @Override
    public int engineSize() {
        return keys.size() + certChains.size();
    }