Emerging Security Challenges for Ubiquitous Devices

In this chapter we focus on two important security challenges that naturally emerge for large scale systems composed of cheap devices implementing only symmetric cryptographic algorithms. First, we consider threats due to poor or malicious implementations of protocols, which enable data to be leaked from the devices to an adversary. We present solutions based on a watchdog concept—a man-in-the-middle device that does not know the secrets of the communicating parties, but aims to destroy covert channels leaking secret information. Second, we deal with the problem of tracing devices by means of information exchanged while establishing a communication session. As solutions such as Diffie-Hellman key exchange are unavailable for such devices, implicit identity information might be transmitted in clear and thereby provide a perfect means for privacy violations. We show how to reduce such risks without retreating to asymmetric algorithms.