How Fingerprint Scanning Works

Fingerprint scanning is the new norm for unlocking your devices, but have you ever wondered how they work and manage to be so accurate? 

Two Common Approaches

One technique for fingerprint scanning is to capture an image of the print under bright light. Also called electro-optical scanning, this method shows the peaks and valleys of a finger print (white and black spaces, respectively), and can be stored and used to compare to future user input. An algorithm is used to compare the black and white spaces of the two images, and if they are nearly identical, access would be granted.

   Another technique called capacitance is also used for fingerprint scanning. This method is commonly used by the IPhone 5 and above, and uses tiny capacitive cells smaller than the ridge of a fingerprint. These cells will close or remain open depending on if they are under a ridge or valley in the print, thereby closing a circuit or allowing current to pass. This information is stored, like the previous model, and used to compare to future input. This method is harder to fool as well, since it requires the shape of the print to work rather than just an image of the print.

Logic and How This Relates to Computer Science

  The logic behind comparing the two inputs can be thought of in very simple computer science terms. Just as we compare the equality of two numbers with == and two strings with .equals(), the two images are checked for similarity in roughly the same way. With electro-optical scanning, the image can be thought of as in binary - black and white corresponding to 1's and 0's. Logically we can say if a certain proportion of those match the original image, then grant access. Else, try again, lock the phone until a valid passcode is entered, or even delete all data on the device depending on your settings.

Conclusion

     Fingerprint scanning is just one part of an expanding realm of biometrics. Some devices have moved to facial recognition such as Windows Hello in Windows 10, while others implement iris scanning similar to what you might see in science-fiction movies. With passwords and personal information being stolen online constantly, I look forward to the day that I no longer have to input and memorize dozens of passwords, and can log in to my accounts for simply being myself.

Sources:
Graphics: http://tinyurl.com/gofbzwn, http://tinyurl.com/h22r2eb
Info: http://gizmodo.com/how-the-iphone-5ss-fingerprint-scanner-works-and-what-1265703794, http://www.windowscentral.com/how-set-windows-hello-facial-recognition-windows-10,