This Specialized Device Can Crack Keypad Codes Automatically

The plan

Although not the most ethical, having to guess at a locked box's multi-digit password can be a very time-consuming task, as each code can take around four seconds to guess, for a total of nearly 4,000 seconds to crack a three-digit passcode. So rather than a finger, the YouTuber who goes by the name Electro Maker decided to use a set of 11 micro servo motors that each press down on a given button to try the various combinations of digits, one after the other and eventually guess the stored code.

Fabricating the device

The device was designed in a couple of hours in Fusion 360, and it consists of an elevated box with the top level containing a ring of eight servo motors with an additional three stacked on top. After 3D printing the required parts, each servo had a horn attached, which reaches down and depresses the button below then it rotates. With the ring assembled, the keypad was then set in the box and surrounded by four standoffs to elevate the servo motors.

Wiring and assembly

An Arduino Mega clone was chosen for this project's microcontroller due to its large number of IO pins for controlling the eleven servos. A small I2C OLED screen was also wired to the Mega, which displays the code currently being checked and if the process has finished. Because this project was merely a demonstration, the keypad below was wired to an Arduino Nano that changes an LED's color to notify the Mega when the code has been cracked via a photoresistor.

How it works

Before the code cracking device has even been powered on, the Arduino Nano is constantly checking if the entered digits match its stored number. Then from 000 up to 999, the servo motors rotate downwards to press the buttons below, where the final servo confirms the entry. After the Nano has lit up its attached LED and the Mega has confirmed the code worked, the digits are reported on the OLED and the process is ended.

Future improvements

For a three-digit password, the device can take up to 29 minutes to find the code 999, and much longer for a four-digit code. Electro Maker plans on swapping out the servos for a faster actuator, such as a solenoid, at some point in the future to help increase the solving speed.