How to Fool Fingerprint Scanners with Residual Prints

by Anonymous

There are two types of fingerprint scanners: optical, and capacitive. It helps to know which type you're dealing with.

If the scanner plate itself is just a peice of clear plastic, with some off-white bits behind it, then it's optical. These ones glow green or blue when they're scanning a print. Capacitive scanners have grey or silver scanner plates, and are completely opaque.

Optical scanners work using an image of the print itself. The finger is pressed against glass, so that at a particular angle the print is very clear.

Capacitive scanners work using a grid of electrodes: the higher parts (ridges) disrupt the conductivity of some electrodes, and the lower parts (valleys) don't. This pattern of disrupted capacitance is the print.

Now, if you have the finger itself (disembodied or otherwise) then access is easy. If, however, you don't, follow these steps.

At this point, it helps to know someone who has access, but it isn't necessary. If you do know them, then getting a print from a glass, a door handle, a steering wheel or similar is needed.

If you don't know someone who has access, then you will need a flashlight, a digital camera, and a chopstick or similar. On the scanner itself, shine the flashlight on the scanning plate until you can see a clear reflection of the previous scanned print. Aim the digital camera at that angle, and use the chopstick as a monopod to steady it. The clearer the picture, the better. This technique can be used to lift prints off of many substances.

Once you have the image of the print, make sure it isn't skewed, and it is resized to the right proportions. Then, in photoshop or something similar, play with the colour levels until the print is clean and distinct, and there is no other detail in the picture. Print the image to a peice of photo paper, and then using an iron or t-shirt press, transfer this image to an unetched circuit board. Then, etch the board as per the instructions (google helps) and you will have a 3D representation of the fingerprint.

Tape the edges of the etched board to create walls, and then pour gelatin into your new mould. Wait 20 minutes for it to set, and then take it out.

The higher the quality of gelatin you buy, the more moisture content it preserves, and the better your gummy finger will be at fooling capacitive scanners. Optical scanners, however, are much dumber.

Walk up to the scanner, take the finger out of your pocket, and press it into the reader. Don't press too hard: too much pressure will crush the gelatin print. Note, some scanners take 3-7 seconds to read a print.

Once inside the restricted area, eat the gummy finger and proceed.