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Archive for April, 2011

Tools: Using X-Ray to pick a lock

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I have this 3×10 digit padlock with an unknown combination. X-Ray seemed like a fun lock-picking tool.

Here is a picture of the padlock. The first tumbler is positioned under the top digit selector. When the tumblers are positioned correctly and the side button is pressed, plungers attached to the lock’s side button assembly are pushed into open space, allowing enough movement to open the padlock. The button on this padlock is spring-loaded, so removing pressure from the button will allow the lock to close (and retract the plungers). If the plungers are not positioned correctly (i.e. incorrect combination) the plungers’ movements will be mechanically blocked.

Below are x-ray pictures of the 3 tumblers with each of [0-9] selected. The padlock was not perfectly re-positioned between digit changes, so the tumbler is not centered across the images. I also modified the kV/mA selections as I was collecting the pictures so some of the images are a bit more saturated than others. The images were captured with the x-ray source positioned beneath the padlock and the detector assembly positioned above the padlock.

I wanted to see if using X-Ray was a feasible lock-picking technique. It turns out that it is, but I had to first figure out what to look for in the X-Ray image. The below images were captured quickly and carelessly. I freely modified multiple variables resulting in a wide range of image qualities. Enough valid information was discernible from the images to make informed guesses at the correct combination (4-2-4). The pictures of the 3rd tumbler are the best set of this bunch.

The regions of darker grey indicate more attenuation of the penetrating x-ray beam (beam is passing through more mass there). We are looking for a cylindrical cavity in each tumbler (open space for the plungers to travel). Since the button actuates in from the side of the padlock, we are looking for a cylindrical cavity that is aligned such that a plunger can enter the cavity with the motion of the button. If I was to retake these images, I would make certain the exact contours of this cylindrical cavity is seen in each picture (at each angle of rotation).

The most informational pictures as the ones that show two ovals in the tumbler. These ovals are the overlapping openings to that cylindrical cavity. As the tumbler is rotated, the cylinder can be seen to rotate as well.  When no ovals are seen, we are looking into the side of the cylindrical cavity (we see the most attenuating mass). When we see distinct ovals, we are looking through one of the openings to the cylindrical cavity, but are still looking through one of the side walls, so less mass total. If both ovals are fully overlapped, we will see a single dark circle enclosing a brighter grey, meaning we are looking exactly down the center of the cylindrical cavity.

Here are pictures of the first tumbler. These are pictures of the padlock configured for each digit 0-9.

Here are pictures of the second tumbler. These are pictures of the padlock configured for each digit 0-9.

Here are pictures of the third tumbler. These are pictures of the padlock configured for each digit 0-9.

The combination ended up being 4-2-4.


Written by sturnfie

April 8th, 2011 at 11:36 pm

Posted in lock-picking,tools,xray