An experimental study of secret key generation for passive Wi-Fi wearable devices

Passive Wi-Fi is a technology to generate 802.11b transmissions using backscatter communication, with power consumption 10000× lower than existing Wi-Fi chipsets. Since wearable devices are typically limited in resources such as power and storage, classical cryptographic security schemes are problematic for them. We instead propose to use wireless channel characteristics to secure data transfer. It has been shown that communicating wireless transceivers are able to generate shared secret keys by measuring channel characteristics at a single frequency. These methods are not applicable to passive Wi-Fi, which uses two different frequencies. In this paper, we describe a method to generate a shared secret key based on wireless channel characteristics in the passive Wi-Fi scenario where the two parties are using dual frequencies.