President Bush has signed a bill stiffening penalties for identity theft, saying criminals who steal someone's good name can now expect to go to jail.

At a White House ceremony, the president also hailed it as an anti-terrorist measure, noting it sets a mandatory five-year prison term for anyone who provides a fake ID to help terrorists.

Identity theft is a big and growing problem. Officials estimate that last year alone, $10 million Americans had their identities stolen. Bush says the cost to the U.S. economy topped $50 billion.

But Bush says sentencing has been inconsistent, with violators too often escaping jail time.

Bush says identity theft "undermines the basic trust on which" the American economy depends, as well as causing consumers months of "grief and hassle."