682 research outputs found
PIANO: Proximity-based User Authentication on Voice-Powered Internet-of-Things Devices
Voice is envisioned to be a popular way for humans to interact with
Internet-of-Things (IoT) devices. We propose a proximity-based user
authentication method (called PIANO) for access control on such voice-powered
IoT devices. PIANO leverages the built-in speaker, microphone, and Bluetooth
that voice-powered IoT devices often already have. Specifically, we assume that
a user carries a personal voice-powered device (e.g., smartphone, smartwatch,
or smartglass), which serves as the user's identity. When another voice-powered
IoT device of the user requires authentication, PIANO estimates the distance
between the two devices by playing and detecting certain acoustic signals;
PIANO grants access if the estimated distance is no larger than a user-selected
threshold. We implemented a proof-of-concept prototype of PIANO. Through
theoretical and empirical evaluations, we find that PIANO is secure, reliable,
personalizable, and efficient.Comment: To appear in ICDCS'1
Strain-induced semiconductor to metal transition in MA2Z4 bilayers
Very recently, a new type of two-dimensional layered material MoSi2N4 has
been fabricated, which is semiconducting with weak interlayer interaction, high
strength, and excellent stability. We systematically investigate theoretically
the effect of vertical strain on the electronic structure of MA2Z4 (M=Ti/Cr/Mo,
A=Si, Z=N/P) bilayers. Taking bilayer MoSi2N4 as an example, our first
principle calculations show that its indirect band gap decreases monotonically
as the vertical compressive strain increases. Under a critical strain around
22%, it undergoes a transition from semiconductor to metal. We attribute this
to the opposite energy shift of states in different layers, which originates
from the built-in electric field induced by the asymmetric charge transfer
between two inner sublayers near the interface. Similar semiconductor to metal
transitions are observed in other strained MA2Z4 bilayers, and the estimated
critical pressures to realize such transitions are within the same order as
semiconducting transition metal dichalcogenides. The semiconductor to metal
transitions observed in the family of MA2Z4 bilayers present interesting
possibilities for strain-induced engineering of their electronic properties
- …