A Key Agreement Scheme for Smart Homes Using the Secret Mismatch Problem

To secure the communications of home area networks, cryptographic keys need to be established between smart home devices. Though many key agreement schemes have been proposed, they cannot be directly implemented, due to the reason that in some applications, smart home devices have no access to the online trusted third party. Moreover, in certain scenarios, the smart home devices are manufactured by different factories. As a result, it is a challenge to securely establish the communication keys using the secrets preloaded by different factories. A few key agreement schemes are designed without using the online trusted third party and the preloaded secrets. However, there are some problems in these schemes. In this article, we improve these schemes and design a key agreement scheme for smart homes such that the devices can automatically and securely establish the communication key. Specifically, our scheme is designed by making use of the secret mismatch problem (exists in the physical layer secret extraction schemes). We prove the security of the proposed scheme and present a prototype implementation. Additionally, we analyze the performance of our scheme and compare it with that of other related works. The comparison shows that our key agreement scheme can fix the problems in the related works, however, it introduces some extra communication consumptions.