Wearable Devices for Per-Touch Authentication
This project proposes a body-guided communication token to secure every touch when users interact with a variety of devices and objects. The method is based on hardware token worn on userís body, for example in the form of a wristband, which interacts with a receiver embedded inside the touched device through a body-guided channel established when the user touches the device.
As users interact with an increasing number of devices, our interaction times with each device become shorter and the overhead of conventional user identification, authorization and authentication solutions places an increasing burden on users. Ensuring authorization or accountability is particularly challenging in environments where devices are operated by groups of people. Therefore, we seek to develop a communication method where wearable devices can help transfer user's identification code to the device within every single touch, offering a seamless, uninterrupted interaction between users and devices while maintaining reasonable security.
The project explores a touch token security solution to exchange credentials with the receiver through a low-power body-guided communication channel that is established at the time the user touches the device. The system consists of a transmitter on the wearable token and a receiver on the touched device. Each side is equipped with two electrodes, and the placement of the electrodes plays an important role in making the system work.
On the wearable side, two electrodes are placed in direct contact with the user's skin, and their electrode spacing is maximized given the size constraint of the wearable token. A microcontroller embedded in the wristband uses a 3Vpp square wave signal to modulate the user's identification code onto these two electrodes.
On the touched device, none of the electrodes have to be in direct skin contact, but one is placed as close as possible to the expected touch-point of the device (usually behind the non-conductive material that the device is made of), while the other electrode is simply floating and even less constrained in position. Signal coming from these two electrodes are then fed into a microcontroller to do real-time decoding.
We developed a prototype and demonstrated the ability to send and decode a 128-bit code in real-time on every single touch (normally lasts about 200ms-2 seconds). We are working on improving the system to make it more practical: adding an activation mechanism on the wearble token to reduce power consumption and improve security, develop two-way communication between the token and the receiver in the touched device.