Tuesday, October 4, 2011

Creating a cheap progressive pin lock set

The other day I gave a presentation to a group of information security students about why they should care about lock picking and how lock picking works.  I wanted to have some hands on material that they could try to pick, but I didn't want to spend a bunch of money buying a progressive pin lock kit.  After all, I don't talk about this very often and I don't need much experience picking a two or three pin lock.  But, if you've got some tools in your garage (or in my case a friend that has tools) you can make your own progressive pin kit on the cheap.

Step one: go out and buy a set of the cheapest locks you can get your hands on.  You're going to grind them up and destroy them so don't buy expensive locks.  Also, this is for practicing simple stuff so you don't want things to get too complicated.  You can buy a set of locks that are keyed alike, but it isn't important since you're going to be picking the locks, not using the key.  There is a non-zero probability that you will really screw up the first one you try so you might consider planning for that in advance.

Step two: Take an angle grinder to the bumps on the bottom of a lock near the keyway.  These are the pins that basically hold the whole lock together.  Here is an action shot of my friend Jeremy grinding down the pins. Try to be careful that you don't damage the keyway itself. 

When you've ground those pins off, you'll probably have to do some work to get the bottom plate off of the lock.  After all, it is designed to not be broken into.  We had to take a chisel and beat at the bottom layer of steel to get it to come off.

When you're done, the actual pin assembly should slide out, and you're looking at the inside of the lock where the shackle release is.  You could unlock the lock with a screwdriver right now.

Here are some optional steps for cleaning things up a bit.  You might want to take a file to the sharp edges that are left of the pins you ground off.  Those are sharp and they could hurt you.  You might also want to drill the holes a bit bigger on the bottom plate that you took off in case you want to put it back on.  Hammer that sucker flat again too since it probably got a bit beat up when you were removing it.

OK, now for the pins.  There are two approaches you could take here: the easy inflexible way or the hard flexible way.  We chose the easy way.  Put your key into the lock mechanism, and turn it 180 degrees.  In our case, the key pins fell out through holes in the bottom of the lock assembly.  So if you want to have a two pin lock, cover up two of the holes and dump the key pins from the other two holes.  Then turn the lock back to the upright position.  This will cause the driver pins to fall into the spot that the key pins were in.  Now turn the lock 180 degrees again and the driver pins will fall out.  After that, put the key in the upright position, and use a tool to sneak the springs out of the lock mechanism.  It's easy, but you can't easily rekey or change the configuration of the lock.

The harder way is to drill out the top of the lock mechanism.  You should see four small holes at the top of the lock if you have a four pin lock.  Drill those holes bigger and you'll be able to take out the spring, driver pin, and key pin.  Then you can rekey to your hearts content and then use some black electricians tape to hold the pins in when you're done.  What if you don't know any black electricians?  Use some other kind of tape.  Now put the whole lock back together if you want or just pick away at the small lock assembly that was inside the padlock. 

Fun fact: hard to believe, but the cheapest lock I could find had three spool pins and only one regular driver pin in it.


andrean lopez said...

It's a bit surprising that the cheapest lock you could find had three spool pins and only one regular driver pin in it. It was really a fun fact.

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kevin thompson said...

Hi Andrean,
If you're interested, I was using an Ace Hardware branded padlock. It looks just like every Master padlock I've ever seen, but with Ace branding.