On the Security of Millimeter Wave Vehicular...

© Robert W. Heath Jr. (2016)

On the Security of Millimeter Wave Vehicular Communication Systems using

Random Antenna SubsetsMohammed Eltayeb*, Junil Choi*, TareqAl-Naffouri#, and Robert W. Heath Jr.*

* Wireless Networking and Communications Group, Department of Electrical and Computer Engineering, The University of Texas at Austin# Electrical Engineering Department, King Abdullah University of Science and Technology(KAUST)

Authors * are funded by U.S. Department of Transportation through D-STOP Tier 1 University Transportation Center and Texas Department of Transportation CAR-STOP


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Security threats in V2XEavesdropping attack Information extraction

T=0: slow down

T=T+τ: slow down

T=T+τ: all clear

Message replayattack

Message falsificationattack

Important to secure communication linksM. Raya, P. Papadimitratos, and J. Hubaux, “Securing vehicular communications,” IEEE Wireless Commun., vol. 13, no. 5, pp.8-15, Oct. 2006.J. Hubaux, S. Capkun, and J. Luo, “The security and privacy of smart vehicles,” IEEE Security and Privacy Mag., vol. 2, no. 3, May 2004, pp. 49-55.


Challenges with existing encryption techniques

3M. Raya, P. Papadimitratos, and J. Hubaux, “Securing vehicular communications,” IEEE Wireless Commun., vol. 13, no. 5, pp.8-15, Oct. 2006.J. Hubaux, S. Capkun, and J. Luo, “The security and privacy of smart vehicles,” IEEE Security and Privacy Mag., vol. 2, no. 3, May 2004, pp. 49-55.

Challenges motivate keyless physical layer (PHY) encryption

Broadcast of public key not possible in mmWave

due to high path loss

Fail if keys are compromised

Require exchange of keys (resource intensive)

Key distribution & management becomes

challenging as the network scales


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Physical layer (PHY) encryption: limitations

Tx uses multiple antennas to degrade

eavesdropper’s channel

Does not rely on upper-layer data encryption or

secret keys

PHY LAYER SECURITY

Traditional PHY encryption not suitable for mmWave

systems(hardware limitations)

MmWave PHY techniques based on switched arrays do not fully exploit the

array gain

LIMITATIONS


Design analog precoderto distort sidelobes

Proposed mmWave PHY encryption approach

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Sidelobedistortion jams eavesdroppers

Exploit alltransmitter antennas

No need for antenna switches

Analog design respects mmWave

hardware constraints


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Two-ray model has beenreported to provide good fit

in open road

System model

Tx Antenna

Phase shifter

gain due to reflected path

H.L.VanTrees,Optimumarrayprocessing(detection,estimation,andmodulationtheory,partIV),1sted.WileyInterscience,Mar.2002.M. Boban, et al., “Geometry-based vehicle-to-vehicle channel modeling for large-scale simulation,” IEEE Trans. Veh. Technol., vol. 63, no. 9, pp. 4146-4164, Nov. 14.

Tx AoD


System model (cont’d)

7H.L.VanTrees,Optimumarrayprocessing(detection,estimation,andmodulationtheory,partIV),1sted.WileyInterscience,Mar.2002.M. Boban, et al., “Geometry-based vehicle-to-vehicle channel modeling for large-scale simulation,” IEEE Trans. Veh. Technol., vol. 63, no. 9, pp. 4146-4164, Nov. 14.

Received signal model

received signal

symbol indextransmit power

path lossRx antenna

gain Tx-Rx channelTx symbol

Tx precoder

noise

Transmitter is equipped with target receiver’s AoD only

Two-ray LOS narrow band channel with

perfect synchronization

All receivers have perfect channel

knowledge


Proposed PHY encryption

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Coherent combiningDestructive combining(Randomized with every

symbol transmission)

Transmit antenna

Destructive combining at Tx distorts sidelobes and jams eavesdroppers

Resulting pattern

distorted pattern distorted pattern Remaining antennas co-phased to destructively

combine at Rx

M antennas co-phased to coherently combine

at Rx


Precoder design

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The nth entry of the precoder f(k) is

Percoder design is based on Analog Beamforming with a single RF chain

transmit symbol index Rx AoD coherent combining subset

even entries of destructive combining subset

odd entries of destructive combining subset


Received signal

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At target Rx

At eavesdropper ( )Rθ θ≠

Beam pattern converges to a random variable at non-Rx directions

( )Rθ θ=transmit

subset size

no. of Txantennas

Rx arraygain

constant

random variable

eavesdropper array gain


Simulation results

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Setup• Frequency 60 GHz, BW = 50MHz, power

37dBm• Standard two-ray channel model• Tx equipped with32 antennas and one RF chain• Rx and eavesdropper equipped with 16 and 32

antennas• Tx subset size is M = 0.75xNT

• Matched-filter Rx beamforming is assumed• Rx distance is 30 m, eavesdropper distance is

10 m• Rx is located along an AoD = 100 deg.

N.Valliappan,etal.,“Antennasubsetmodulationforsecuremillimeter-wavewirelesscommunication,”IEEETrans.Commun.,vol.61,no.8,pp.3231-3245,Aug.2013.

Secrecy throughput

SNR at target receiver

SNR at eavesdropper

High secrecy throughput except at AoD = 100o


Varying the transmission subset size

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There is an optimal subset size that maximizes the secrecy throughputN.Valliappan,etal.,“Antennasubsetmodulationforsecuremillimeter-wavewirelesscommunication,”IEEETrans.Commun.,vol.61,no.8,pp.3231-3245,Aug.2013.

Using all antennas increases the beam pattern variance at non-Rx directions when compared to switched array

techniques


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Conclusions Eavesdropping attack Information extraction

T=0: slow down

Message replayattack

Message falsificationattack

Proposed technique is keyless and

transparent to existing receivers

Large dimensional antenna arrays can be

exploited to jam eavesdroppers

Proposed technique can be used to

augment higher layer security techniques


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Questions?

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