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Lock Blog

A resource for consumers, locksmiths, and security professionals

Key Decoders: What They Are And How They Work

by Taylor August 15, 2022

There are thousands upon thousands of possible key combinations out there. That’s what makes locks work – generally, no two keys will ever be alike. You must make randomized lock combinations to ensure the key is unique.

Keys are made with specific codes that designate what their cut is. They’re assigned numbers to indicate the depth of each key cut. Depending on the brand, keys have anywhere between three to even eight or more cuts on the blade. Each one is at a randomized and different depth. This process is what makes the key unique.

So let’s say you need to find out what this code is. There could be a few reasons for wanting to know this. The most common one is that you or a client needs one or more keys for a lock, and you only have a broken key for reference.

You can’t line up the key fragments on a key cutter to make a duplicate, but you can decode what remains of the key. But how do you figure out what a key’s code is based only on the key or lock? Well, you use a key decoder.

There are a few varieties of key decoders out there, depending on the lock you’re using. The most common type requires the key to be present, but several other types only require the lock to decode. So how do they work? How do you use key decoders to figure out the code of a lock or key?

Here’s a list of the types of key decoders:

  1. Pin Tumbler and Wafer Decoders
  2. Disk Detainer Decoders
  3. Tubular Decoders
  4. SmartKey Decoders

1. Pin Tumbler and Wafer Decoders

The most common of the key decoders goes along with the most common type of lock: the pin tumbler lock. You’ll find these locks on your front doors and on most padlocks. When you think of locks, you’re thinking of pin tumbler locks.

Wafer locks are very similar, using wafers instead of pins like the name suggests. You’ll find them on cars, desk drawers, and cheaper padlocks. The most common decoders for these two lock types work the same.

With Spare Key

These key decoders require the key to be present. You also need to know what brand of lock you’re dealing with to use them. As a result, these aren’t picking tools. Some other decoders can pick or bypass a lock, but no criminal or even locksport enthusiast will get any use out of these types of pin tumbler key decoders. These are purely for making duplicate keys.

You will need to take the key and determine the brand. The brand is usually visible somewhere. Often it’s written on the head of the key (but not always). An experienced locksmith can sometimes know the brand by looking at the shape of the key.

Once the brand is determined, the correct key decoder for the brand needs to be acquired. Different brands build keys slightly differently, and if you want to decode correctly, you need the proper decoder. Otherwise, the numbers will be slightly off, and you’re not going to get a duplicate key.

The decoder looks like a rectangle with a sloping rectangular hole in the middle. There should be numbers at different points in the slope, usually starting at 0 and going up to 7-9.

To use the decoder, all you need to do is stick the key into the holes and see which numbered section each cut best fits into, telling you the depth of that specific cut. Measure each of the cuts from the tip of the key to the head. Write down each of the numbers in sequence.

The number you end up with is the key’s code. Using these decoders is pretty straightforward. It also requires the key, which means it’s not helpful in situations where the key is lost.

No Spare Key

A tool like the Lishi decoder only needs the lock. You don’t need the original key. A Lishi 2-in-1 tool is a lockpicking aid that doubles as a decoder, hence “2-in-1.” You must pick the lock first before decoding it. If your key is broken in the lock, remove it first.

This tool is a flat metal rectangle with a pick and tensioner and a chart written on the side. While you use the pick, a little hook should be lining up with numbers on the chart.

After picking the lock, line up the hook with each indicated pin and see what number it drops down to. That’s your lock’s code. Now you can make a key from just the lock.

2. Disk Detainer Decoders

Disk detainer locks consist of rotatable disks that a key moves when inserted. They’re a little like dialable combination locks, except they use a key mechanism instead of a dial.

Disk detainer decoders are a little more complicated to use. Just by looking at them, it’s hard to figure out how to use all of the various bells and whistles.

However, while they’re more complicated to use, they’re still remarkably easy to use. And they not only decode a key, but like a Lishi decoder, you can also use them to pick the lock as well. 

All in all, they’re a solid tool choice for beginner lock pickers. These devices are metal cylinders with a tip that looks like key bitting. Around the cylinder is a series of handles.

Some versions of these key decoders have only one handle and an extendable series of rotatable disks that serve the same function as the handles, although this is rare. Next to these handles should be numbers, usually labeled 1-4.

Once again, you need to know the brand of lock that you’re decoding. The decoder tools are not universal. Different brands require different key decoders.

To decode a disk detainer lock, insert the decoder into the keyhole and turn every handle/dial as far as it goes. Most should go far, but some will barely move at all. The ones that barely move are vital for unlocking the lock, as you need them for tension pressure. Push on these to simulate the turning of a key.

The remaining dials should have some wiggle room before you feel them catch on something. Pushing through, you should find more wiggle room before hitting another catching point. Keep doing this, and find the area with the most wiggle room. This wiggle won’t be subtle – the wiggle room will dramatically increase at some point.

You need to find the correct wiggle room location for each dial. After you do that, the lock should open, and the device should be communicating the code to you. But how would it do that? To find the answer, look at how the dials look now.

Remember the numbers on the dials? You have now lined them up in a specific way. Look at the dials that didn’t turn and find the highest number written there. This number should be either 4 or 3. That’s the value of that dial. Mentally draw a straight line (or put a straightedge next to it) to the numbers above and below. Those are the values of the other dials.

Write these values down in sequence. That’s the code of that key.

3. Tubular Decoders

There’s a rare type of lock called a “tubular lock.” These are essentially pin tumbler locks with the pins in a circular shape. The keys look like tubes inserted into what looks like an on/off symbol.

You’ll need the key or the tubular lock pick to decode a tubular lock. Tubular lock picks reshape themselves into the shape of the key, so once you pick the lock, it’ll be just as effective as a real key.

These key decoders either look like a sheet of plastic with bumps on them, or they look a lot like regular non-tubular keys with bitting used to measure the depth of the cuts. Each of these bumps should have a number next to them.

To decode a tubular lock, measure the bitting against the bumps in the decoder and write down the corresponding numbers. Work clockwise from the top until you get all around the key. It’s as simple as that. These are not the most complex key decoders.

4. SmartKey Decoders

There are key decoders made for the brand of Kwikset SmartKey locks. These are not the same as “smart locks,” which are electronic locks that operate off of a second device (like a smartphone) to open instead of relying on a physical key. There are other ways to define smart locks, but regardless, these are not examples of electronic smart locks.

A Kwikset SmartKey lock has a cylinder that the owner can rekey without using new pins or locksmith tools. These are very hard to pick and fragile, making them a mixed bag in quality. And if they break, that can make them very difficult to decode or unlock if necessary.

 Key decoders were developed especially for this type of lock. Essentially, all this decoder is a key-shaped camera. You put a buffer on the key, insert it into the lock, and it takes a picture of the inside. It sends this picture to your mobile device. The buffer ensures the camera is just under each pin inside the lock so that the image is accurate.

After getting the picture, you compare it to a chart to see the depth of each pin. You number the depth from front to back, and that’s your code. It’s pretty simple.


What is a Tibbe lock pick?

A Tibbe lock is a specific car lock used mainly in Fords and Jaguars. They’re more popular in Europe than they are in the United States.

These have a specific pick that you can use to decode and pick open the car lock easily. The device consists of rotating disks with handles. These correspond to the disks inside the lock.

What is a tubular key decoder?

Key decoders for tubular keys tell you what the key of a tubular lock looks like using a series of numbers. To decode a tubular key, you must either have the key with you or have a tubular lock pick. This pick is a device that reshapes itself to look like a key. You measure the bumps in the decoder against the grooves in the key and write down the corresponding numbers.

How do you use a key decoder tool?

It depends on which of the many key decoders you’re using, but generally, they involve measuring a key to determine how deep each groove in the key is and writing down numbers that correspond to a key’s depth.

What is a car key decoder?

You can use car key decoders to determine how a car key is cut and duplicate said key. The depth of each cut has numerical values, which would then correspond to the duplicate key.

How do you use a Tibbe key decoder?

First, you insert a Tibbe key decoder into the lock. You then rotate the handles as far as they can go. Place pressure on the handles that can’t turn. Then the wiggle room of each handle is tested out against catching points. You find the spot with the most wiggle room and see which number the handle is on.


Key decoders can change from type to type. It depends heavily on the lock you’re decoding and the particular brand. All in all, you need to be well prepared to use key decoders properly.

Fortunately, these tools are all relatively easy to use. That makes them a great double-whammy of being more or less useless to burglars while being incredibly useful to people who need them for legitimate reasons. 

A thief isn’t going to know what kind of lock they’re dealing with, while a professional locksmith is. Decoding a lock is very useful for making new keys, and it’s great that there are easy and effective ways to do it.

Category: Lock Picking, Tools of the Trade

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