CamTalk: A Bidirectional Light Communications Framework for Secure Communications on Smartphones

In this paper we present CamTalk, a novel bidirectional communications framework using front-facing cameras and displays of smartphones. In the CamTalk framework, two smartphones exchange information via barcodes: information is encoded into barcodes that are displayed on the screen of the origin device, and those barcodes are captured by the front-facing camera of the destination device and decoded; Both devices can send and receive barcodes at the same time. The general design of data transmission enables CamTalk to support a wide range of applications. More importantly, CamTalk’s communications channels are short-range, highly directional, fully observational, and immune to electromagnetic interference, which makes CamTalk very appealing for secure communications and bootstrapping security applications. We have implemented CamTalk on the Android platform and conducted extensive experiments to evaluate its performance on both Android smartphones and tablets. Our experimental results demonstrate the efficacy of CamTalk in short-range wireless communications.