Abstract. "Pairing" is referred to as the operation of achieving authenticated key agreement between two human-operated devices over a short- or medium-range wireless communication channel (such as Bluetooth, WiFi). The devices are ad hoc in nature, i.e., they can neither be assumed to have a prior context (such as pre-shared secrets) with each other nor do they share a common trusted on- or off-line authority. However, the devices can generally be connected using auxiliary physical channel(s) (such as audio, visual) that can be authenticated by the device user(s), and thus form the basis for pairing. One of the main challenges of device pairing is the lack of good quality output interfaces (e.g., a speaker, display) as well as receivers (e.g., a microphone, camera) on both devices. In this paper, we present a new pairing scheme that is universally applicable to any pair of devices, supporting all possible pairing scenarios. Our scheme does not require devices to have good tr...