Simple and Secure Pairing for Bluetooth Smart

The purpose here is to develop a pairing method, which can be realized by simple means. The pairing should be intuitive and secure and lay the basis for a subsequent encrypted data exchange. A universal application for a preferably large variety of devices is crucial.  Secure pairing is already possible with NFC. However, this method is expensive. Therefore, most of the Bluetooth Smart peripheral devices do not integrate an NFC-Chip. In this example, we use the display of a smartphone to generate an optical signal. A key (randomly selected by the smartphone app) is sent in form of a flashing pattern and received by a sensor on the tag. The tag is placed on a marked area of the display. A key is derived from the decoded light pattern data, which is used to encrypt the subsequent communication.