What Are Bump Keys? How To Prevent Lock Bumping

Imagine coming home from a nice night out at a restaurant, and you open your front door to discover that your home has been ransacked and burglarized. After the initial shock wears off, you look for signs of a forced entry, but can’t find any. Your windows and other exterior doors are all intact, and your locks show no signs of being broken or picked. 

How in the world did that criminal get into your house? It’s almost as if they had their own key to your home and just waltzed right in. The unsettling reality is that if the criminal used a technique called lock bumping, that’s exactly what they did.

While lock security has improved in recent years, millions of standard, low-cost pin-and-tumbler deadbolts are still installed on homes and small commercial properties today. Let’s take a closer look at what bump key attacksare and how to make your home or business more secure. 

What is a Bump Key?

Bump keys are specially cut keys that bypass the security mechanisms built into traditional pin-and-tumbler locks. Bump keys are also called “999 keys” because all their ridges are cut to the maximum depth (999) on a key-making machine. Abump key setis relatively easy to produce (it typically takes less than five minutes to cut a bump key), and not very difficult to acquire. 

Bump Key Attack: How Does it Work? 

Bump keys exploit a vulnerability in pin-and-tumbler locks related to the pin stacks, the spring-loaded stacks of pins that keep the lock cylinder from turning without a proper key. In a typical pin-and-tumbler lock, there are two sets of pins: driver pins and key pins. Each pin stack within the lock is occupied by one driver pin and one key pin, both of which are pressed tightly against each other by way of a small spring attached to the driver pin. 

The point where each set of pins meets is different for each pin stack, which is why a typical key is cut at different depths to accommodate this intentional misalignment. Once the correct key is inserted, it aligns the meeting points of each pin stack, creating what is known as a “shear line.” Once the shear line has been formed, the lock can freely rotate within the cylinder, allowing the door to be opened.

A bump key is cut in such a way that it will not properly align with the pins, but instead will simply disrupt the pins when the bump key is struck by an object such as a screwdriver or small hammer. The energy from striking the bump key transfers to the pins inside the lock, causing them to jump and create a temporary shear line, giving the intruder just enough time to turn the lock and open the door. 

When done correctly, lock bumping works on nearly 90 percent of cylinder-type locks. 

The Danger of Bump Key Attacks 

Aside from the burglary itself, perhaps one of the most disconcerting aspects of lock bumping is that it can often go undetected. This means that your home can be broken into without any signs of forced entry. 

This in itself can be disturbing, but it also makes investigations more challenging. To a police investigator or an insurance adjuster, the door simply looks as though it was unlocked or opened with a standard key.

Insurance companies require policyholders to prove a loss occurred. When there are no signs of forced entry, insurance companies may have several grounds for denying claims. 

• Allegations of negligence, such as claiming the homeowner simply forgot to lock the door.

• Questioning whether an actual burglary took place versus an inside job or unverified missing property.

• Forcing the policyholder to undergo lengthy investigations or legal disputes to receive a payout for stolen items.

While forensic locksmiths can sometimes detect microscopic scratches or indentations left inside the keyway by a bump key, hiring a forensic expert to inspect the lock after a burglary costs hundreds or sometimes even thousands of dollars. Compared to the amount of the insurance payout, it’s often difficult to justify the expense. 

How to Prevent Bump Keying 

The best way to prevent bump key attacks is to replace or upgrade any pin-and-tumbler deadbolts at your property. Here are a few options. 

Switch to Keyless Locks 

If there’s no keyhole, lock bumping is physically impossible.Smart locks are accessed with PIN codes, RFID fobs, or even mobile apps. Meanwhile,mechanical keyless locks rely on internal tumblers and require no batteries, wiring, or physical keys. 

Install Smart Deadbolts with High-Security Key Overrides

If you want a smart lock with a physical backup key, check that the key cylinder is designed to resist bumping attacks. Some locks use spool or mushroom-shaped pins that make key bumping more difficult, while others use a sidebar mechanism that resists standard bump keys. Look for a high-security rating, such as ANSI/BHMA Grade 1, such asSchlage Encode orYale Assure. 

Install Locks with Anti-Bump Cylinders 

If you want to keep standard physical keys for your building, you can often replace basic residential pin-tumbler deadbolts with high-security mechanical cylinders. 

• Brands likeMedeco are designed with dual-locking mechanisms and rotating bottom pins. Standard bump keys don’t work in this type of cylinder because the key needs to elevate and rotate the internal pins in order to create a shear line. 

• Upgrade standard lock housings with commercial-grade replacement cylinders that are designed with anti-bump spool pins. Look for options such asCorbin Russwin 8000-59A1orSchlage 30-137.

Protect Your Property with GoKeyless

Bump key attacks are unfortunately very easy on standard pin-and-tumbler locks. But luckily, protecting your home against these attacks is also easy. Whether you want to eliminate keyholes with a smart lock, upgrade to a more secure deadbolt, or swap out your lock cylinders, GoKeyless is here to help. 

Browse our massive selection of keyless deadbolts to get started, and reach out to theGoKeyless Cares team for help choosing the best option for your property.