Unlocking the truth behind bump keys

How to avoid break-ins at your home

Last reviewed: June 2011
Bump key

Web videos that demonstrate how to make a "bump key" are especially unnerving because unlike so much other sketchy content online, these tutorials are real. These instructional pieces typically reveal that any key "when properly used, will open any lock that it fits into," as boasts one Web instructor.

A bump key is made by taking a key that already fits into a particular brand of lock and filing it down. But turning a blank key into a bump key isn't as simple as it looks in those Web videos.

First, a key must fit into the lock someone wants to pick—even if the key can't open the door, it must slide all the way into the lock. A thief would also need to schlep around hundreds of keys to the home(s) they intend to enter since there are so many different key fits on the market.

"Just think of the selection displayed when you get a key duplicated in a hardware store," says John Galeotafiore, our director of testing for home improvement.

Next, the crook would need to file the cuts in the key down to the deepest depths and then use a "bumping" tool to bounce the pins and open the lock.

"Ultimately, the consumer is responsible for assessing the risk of an attack from bumping," wrote Marc Weber Tobias, author of Locks, Safes, and Security. In a 2006 analysis on lock bumping, Tobias pointed out that apartment buildings or business complexes that utilize one standard lock brand and model face a high risk of having their locks compromised. The same goes for homeowners whose old keys fall into the wrong hands after a lock has been changed for a similar model.

The bump key phenomenon has received widespread media coverage in recent years—the idea that any handy hooligan can easily gain easy access to your home makes a compelling story on the evening news. But, says Galeotafiore, "Lock bumping shouldn't be a consumer's first worry when it comes to the security of his or her home."

The FBI qualifies lock bumping as forcible entry and attempted forcible entry burglary, crime categories that accounted for more than 60 percent of U.S. burglaries in 2008.

The best defense against home burglary? The National Crime Prevention Council (NCPC) advises that you install a high-quality lock. "Not all locks can be bumped; consumers just need to know the difference," says Clyde Roberson, technical director at Medeco Security Locks, a company that consults with the NCPC. "Consumers should consider using quality high-security locks for their home or business in order to have adequate protection from bumping and other forms of lock attack." A high-security lock is pick resistant and provides protection against drilling, and duplication of the key is controlled.

In our tests of door locks, we found that far too many door locks come with a strike plate, or the proper screws, that can resist efforts to kick a door in. And only expensive high-security locks were able to withstand an assault from a standard cordless drill and our consulting locksmith trying to pick the locks. That added security comes at a price. The high-security locks we tested cost $95 and $190, compared with $12 to $50 for inexpensive locks. Even $25 locks can provide excellent protection against the most common type of forced entry—kicking the door open—but not necessarily with the strike plate that's included.

You can significantly strengthen any lock by replacing the strike plate (the metal plate that's mounted on the doorjamb and into which the lock bolt slides) with a $10 box strike such as the Mag High Security Box Strike. Another inexpensive way to enhance your current door lock is to replace the typical short mounting screws with 3-inch-long ones. They will penetrate the doorjamb and go into the studs, providing more resistance to impact.