April 23, 2013
Use your body’s electric field to authenticate
As the world continues to convert objects into digital identifiers and expand the Internet of Things, electronics manufacturers are expanding their product offerings to take on this exciting transformative opportunity. Arizona-based Microchip Technology has recently developed a system that uses a person’s own electrical field to transfer and communicate information. Their system, called BodyCom, has numerous applications, ranging from authentication and pairing, to safety and automation scenarios.
While passive RFID technologies can be employed for some of this kind of activity, they don’t offer the level of security or extensible programmability that BodyCom has to offer. Plus, BodyCom’s claim to fame is that it must be within a small radius near a living human body to work.
Figure 1: The BodyCom concept.
BodyCom works via capacitive coupling and allows for bidirectional communication with a controller. In other words, your body becomes the electrical conduit that the BodyCom system uses to communicate. As such, the system uses the body as a means of authentication. It also prevents relay attacks due to its proximity and conformity with the body it is using as its conduit. And because the system also supports AES-128 and other encryption approaches, it can be used with far more confidence than a traditional RFID key-lock system.
Developing a BodyCom Application
Microchip offers the BodyCom Development Kit for $149, which can be directly ordered from their website. The development kit consists of a programmable base station board and two generic keyfob-enclosed mobile units. The base station uses a PIC16LF1829 20-pin Flash MCU with XLP technology that can be programmed and powered via the included mini-USB to USB 5V cable connected to a computer running Microsoft Windows. The board can also be powered via a standard 9V power supply. The main development board also hosts a 16×2 character LCD with backlight and controller for basic information display. There are also several push buttons, LED’s, prototyping pins, jumpers, and two coupling board pads for easy prototyping.
Figure 2: The BodyCom development kit.
The mobile units use a PIC16LF1827 18-pin Flash MCU, two LED’s, and several other components to help minimize power consumption because they need to be actively powered by a 3V battery to work. Both the base and mobile units feature on-chip programmable Flash memory and EEPROM storage for custom development.
It took me about ten minutes to get oriented with the board, and even less time to connect it to my computer and run the demonstration program included in the development kit software.
Unfortunately, the SDK is Windows-only at this time, with no Mac or Linux version in sight. Fortunately, the board and mobile units come preloaded with a demonstration program that can be operated using the four push buttons and the LCD via a simple navigational menu to check for BodyCom Eval Touch, Eval Proximity, Debug Menu, and View Mobile ID. These provide a quick way to verify that the hardware is working correctly.
The development software running on a Windows PC offers basic boot and application loading, as well as serial monitoring of the board’s activity. The user interface isn’t exciting and could use some polish, but it is functional. After studying the demo code that accompanies the SDK, I was able to create a very simple detection program that validated the specific mobile unit I used. I would like to further extend the idea to home automation and use the BodyCom system for a door lock scenario, similar to the one I wrote about in my book, Programming Your Home.
However, until Microchip Technology offers an easy way to hook in events from the main board with a serial library example application that lives within a COM object or .NET library I can repurpose for my own programs, this will have to wait for a rainy day when I have the time to code up a custom approach instead.
The BodyCom System Development Kit offers a unique way to use the human body as a conduit for authentication and security. There is enough electronics on the main board to mock up prototypes for a variety of applications. As Microchip Technology continues to iterate on this idea, there’s no doubt that the components (especially the mobile units) will become smaller and less expensive over time. Eventually, it’s possible that we will see BodyCom-enabled devices in consumer electronics, ATM’s, company entrances, vehicles, and more. Get ready for the Internet of Things where man meets machine.
For more information about BodyCom, visit Microchip Technology’s Web page.