Engler and Vines built their bot, shown briefly in a preview video, from three $10 servomotors, a plastic stylus, an open-source Arduino microcontroller, a collection of plastic parts 3D-printed on their local hackerspace's Makerbot 3D printer, and a five dollar webcam that watches the phone's screen to detect if it's successfully guessed the password. The device can be controlled via USB, connecting to a Mac or Windows PC that runs a simple code-cracking program. The researchers plan to release both the free software and the blueprints for their 3D-printable parts at the time of their Def Con talk.
In addition to their finger-like R2B2, Engler and Vines are also working on another version of their invention that will instead use electrodes attached to a phone’s touchscreen, simulating capacitative screen taps with faster electrical signals. That bot, which they’re calling the Capacitative Cartesian Coordinate Brute-force Overlay or C3BO, remains a work in progress, Engler says, though he plans to have it ready for Def Con.