Under the open-source model, thousands of people pick it apart simultaneously and increase security. It comes more cheaply than computer coding designed for a single client, such as the Executive Office of the President. It gives programmers around the world a chance to offer upgrades, additions or tweaks to existing programs that the White House could — or could not — include in daily updates. Yet the system — known as Drupal — alone won't make it more secure on its own, cautioned Ari Schwartz of the Center for Democracy and Technology.