328 research outputs found
Gait-Based Smart Pairing System for Personal Wearable Devices
With the rapid development of embedded technology and mobile computing, we have seen a growing number of Internet of Things (IoT) devices on the market. As the number of wearable devices belonging to the same user increases rapidly, secure pairing between legitimate devices becomes an important research problem. In this chapter, we propose the first gait-based shared key generation system that assists two devices to generate a common secure key by exploiting the user’s unique walking pattern. The system is based on the fact that sensors on different positions of the same user exhibit similar accelerometer signal when the user is walking. Therefore, the acceleration can be used as a shared secret information to generate a common key on different devices independently. Our experimental results show that the key generated by two independent devices on the same body is able to achieve 100% bit agreement rate. The proposed key generation protocol can establish a 128-bit key in 5 s (about 10 steps) with entropy varying from 0.93 to 1. We also find that the proposed scheme can run in real time on modern smartphone and require low system cost
Highly tunable spin-dependent electron transport through carbon atomic chains connecting two zigzag graphene nanoribbons
Motivated by recent experiments of successfully carving out stable carbon
atomic chains from graphene, we investigate a device structure of a carbon
chain connecting two zigzag graphene nanoribbons with highly tunable
spin-dependent transport properties. Our calculation based on the
non-equilibrium Green's function approach combined with the density functional
theory shows that the transport behavior is sensitive to the spin configuration
of the leads and the bridge position in the gap. A bridge in the middle gives
an overall good coupling except for around the Fermi energy where the leads
with anti-parallel spins create a small transport gap while the leads with
parallel spins give a finite density of states and induce an even-odd
oscillation in conductance in terms of the number of atoms in the carbon chain.
On the other hand, a bridge at the edge shows a transport behavior associated
with the spin-polarized edge states, presenting sharp pure -spin and
-spin peaks beside the Fermi energy in the transmission function. This
makes it possible to realize on-chip interconnects or spintronic devices by
tuning the spin state of the leads and the bridge position.Comment: 7 pages, 9 figure
Sn(II)-containing phosphates as optoelectronic materials
We theoretically investigate Sn(II) phosphates as optoelectronic materials
using first principles calculations. We focus on known prototype materials
SnPO (n=2, 3, 4, 5) and a previously unreported compound,
SnPO (n=1), which we find using global optimization structure
prediction. The electronic structure calculations indicate that these compounds
all have large band gaps above 3.2 eV, meaning their transparency to visible
light. Several of these compounds show relatively low hole effective masses
(2-3 m), comparable the electron masses. This suggests potential
bipolar conductivity depending on doping. The dispersive valence band-edges
underlying the low hole masses, originate from the anti-bonding hybridization
between the Sn 5s orbitals and the phosphate groups. Analysis of
structure-property relationships for the metastable structures generated during
structure search shows considerable variation in combinations of band gap and
carrier effective masses, implying chemical tunability of these properties. The
unusual combinations of relatively high band gap, low carrier masses and high
chemical stability suggests possible optoelectronic applications of these
Sn(II) phosphates, including p-type transparent conductors. Related to this,
calculations for doped material indicate low visible light absorption, combined
with high plasma frequencies.Comment: 10 pages, 10 figures, Supplementary informatio
H2B: Heartbeat-based Secret Key Generation Using Piezo Vibration Sensors
We present Heartbeats-2-Bits (H2B), which is a system for securely pairing
wearable devices by generating a shared secret key from the skin vibrations
caused by heartbeat. This work is motivated by potential power saving
opportunity arising from the fact that heartbeat intervals can be detected
energy-efficiently using inexpensive and power-efficient piezo sensors, which
obviates the need to employ complex heartbeat monitors such as
Electrocardiogram or Photoplethysmogram. Indeed, our experiments show that
piezo sensors can measure heartbeat intervals on many different body locations
including chest, wrist, waist, neck and ankle. Unfortunately, we also discover
that the heartbeat interval signal captured by piezo vibration sensors has low
Signal-to-Noise Ratio (SNR) because they are not designed as precision
heartbeat monitors, which becomes the key challenge for H2B. To overcome this
problem, we first apply a quantile function-based quantization method to fully
extract the useful entropy from the noisy piezo measurements. We then propose a
novel Compressive Sensing-based reconciliation method to correct the high bit
mismatch rates between the two independently generated keys caused by low SNR.
We prototype H2B using off-the-shelf piezo sensors and evaluate its performance
on a dataset collected from different body positions of 23 participants. Our
results show that H2B has an overwhelming pairing success rate of 95.6%. We
also analyze and demonstrate H2B's robustness against three types of attacks.
Finally, our power measurements show that H2B is very power-efficient
Securing Cyber-Physical Social Interactions on Wrist-worn Devices
Since ancient Greece, handshaking has been commonly practiced between two people as a friendly gesture to express trust and respect, or form a mutual agreement. In this article, we show that such physical contact can be used to bootstrap secure cyber contact between the smart devices worn by users. The key observation is that during handshaking, although belonged to two different users, the two hands involved in the shaking events are often rigidly connected, and therefore exhibit very similar motion patterns. We propose a novel key generation system, which harvests motion data during user handshaking from the wrist-worn smart devices such as smartwatches or fitness bands, and exploits the matching motion patterns to generate symmetric keys on both parties. The generated keys can be then used to establish a secure communication channel for exchanging data between devices. This provides a much more natural and user-friendly alternative for many applications, e.g., exchanging/sharing contact details, friending on social networks, or even making payments, since it doesn’t involve extra bespoke hardware, nor require the users to perform pre-defined gestures. We implement the proposed key generation system on off-the-shelf smartwatches, and extensive evaluation shows that it can reliably generate 128-bit symmetric keys just after around 1s of handshaking (with success rate >99%), and is resilient to different types of attacks including impersonate mimicking attacks, impersonate passive attacks, or eavesdropping attacks. Specifically, for real-time impersonate mimicking attacks, in our experiments, the Equal Error Rate (EER) is only 1.6% on average. We also show that the proposed key generation system can be extremely lightweight and is able to run in-situ on the resource-constrained smartwatches without incurring excessive resource consumption
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