Flashing displays: User-friendly solution for bootstrapping secure associations between multiple constrained wireless devices

Abstract

Future healthcare systems, smart homes, and similar will involve a large number of smart inter-connected wireless devices (such as wireless sensor nodes). One of the major challenges to securing these systems presents loading initial cryptographic credentials into a relatively large number of wireless devices. Furthermore, many of these technologies involve low-cost and highly interface constrained devices (lacking usual wired interfaces, displays, keypads, and alike). We propose two novel multichannel key deployment schemes for wireless networks that only require a presence of a light source device, such as a multi-touch screen (tablet or smartphone device). The first key deployment scheme is based on secret key cryptography and is suitable for interface/resource-constrained wireless devices. The second scheme assumes a strong attacker and requires the use of public key cryptography. In both our solutions, we use one-way visible light channel of multi-touch screens (flashing displays) to initialize devices in a secure, usable, and scalable way. From the user's perspective, this boils down to placing the devices on the multitouch screen after which the remaining process is fully automatized. We showed through the experiments with 48 users that our solution is user-friendly and scales linearly with the number of nodes.