Spreading alerts quietly: New insights from theory and practice

With the emergence of the Internet of things and of electronic home health-care, more and more sensitive signals are transiting over easily accessible wireless networks. It has become an important task to manage to spread alerts on a wireless network at the same time as to hide the nature of these signals, in a secure and efficient way. No one (an adversarial observer or even the node transmitting the signal) should be able to learn whether a signal corresponds to an alert or a normal echo. Blind Coupon Mechanism is a primitive proposed at Asiacrypt 2005 that allows to spread such alerts quietly and quickly. In this paper, we propose to strengthen their security model and we give a concrete solution which is both more secure and more efficient than the protocol originally proposed.