Cross Layer Design of Security Scheme for Cooperative MIMO Sensor Networks

Wei Chen, McKenzie McNeal, Liang Hong

College of Engineering, Technology, and Computer Science Tennessee State University, USA

IEEE International Conference on Wireless Information Technology and Systems , 2010 ICWITS 2010

Outline



Introduction to Virtual MIMO Technology

 Cooperative communication schemes  Virtual MIMO networks and cooperative relay 

Research Objectives



Cross-Layered Design of Security Scheme

 Cryptography based security routing protocol at network layer  Compromised node detection at physical layer  Data recovery and network recovery 

Preliminary Performance Analysis



Summery and Future Work

Introduction to Virtual MIMO technology

MIMO (Multi-Input Multi-Output) Technology

Without using extra energy and channel, a MIMO transceiver can be used to  Extend communication range or reducing error rate (diversity gain)  Provide higher data rate (multiplexing gain)

MIMO transceiver

T × 1 T × 2 R × 1 R × 2

Wireless MIMO network

T × M R × M

diversity gain multiplexing gain However, it is unrealistic to equip multiple antennas to small and inexpensive wireless devices (e.g., crossbow sensor nodes).

Introduction to Virtual MIMO technology – Cooperative Communication schemes

Cooperative transmission and reception Distributed individual single-antenna nodes cooperating on data transmission and reception as a multi-antenna MIMO node

Different types of cooperative MIMO links

MIMO Link The

i

th node’antenna acts like the

i

th antenna The

j

th node’s antenna acts like the

j

th antenna MISO Link SIMO Link SISO Link

Introduction to Virtual MIMO technology – Virtual MIMO Networks and Cooperative Relay

Virtual MIMO nodes & relay backbone Cooperative MIMO links 3 × 2 MIMO link virtual MIMO node relay backbone

Multi-MISO based cooperative data relay

three 4 × 1 MISO links

d

three 4 × 1 MISO links

A B B C D

Other hops First hop Step 1 (Local transmission at A):

Each node

i

(1

≤i≤m

) in

A

broadcasts information to all the other local nodes using different timeslots.

Step 2 (long-haul transmission between A and B):

Each node

i

in

A

acts as the

i

th antenna encoding the information sequence using the MISO code system. All broadcast encoded sequence to the nodes in

B m

nodes in

A

at the same time. Each node in

B

receives

m

encoded sequences, and then decodes them back to

I

according to the MISO code system.

Research Objectives

– Previous Research Works

Cryptographic based security schemes

Securing communication and routing between healthy nodes, but doing nothing to compromised nodes

MIMO technology based data assurance schemes

  Li

et al

& Kim

et al

[5,6]: Exploit signal randomization and channel diversity in physical layer to effectively randomize the eavesdropper’s signals but not the authorized receiver’s signals (Wen

et al

[7]): Add artificial noise (known by the authorized receiver and generated by the keys in network layer) to transmission process in physical layer. The schemes need extra MIMO antennas to achieve the data assurance, which largely reduces the MIMO advantage.

Research Objectives

This Research

Combining the cryptographic technique in network layer with data assurance analysis at physical layer to provide: 1.

2.

3.

Efficient key management system to secure communication and routing in network layer MIMO-aid compromised node detection at physical layer Data recovering and network recovering

Security Protocol at Network Layer

– Shared key cryptography for cooperative communication/routing

C-key(A) A L-key(A,B) B C-key(B)

Type of Keys (1) Each cluster:

each node has a cluster key

C-key(A)

for local transmission

(2) Each link AB:

each node in

A

and

B

has a key

L-key(A,B)

for long haul transmission between

A

and

B

Secured cooperative relay: Step 1 (Local transmission at A):

Each node

i

(1

≤i≤m

) in

A

encrypts its information with

C-key(A), and

node uses

C-key(A)

broadcasts it to other local nodes using different timeslots. Each to decrypt the received

m I

 2 ,...

I

Step 2 (long-hul transmission between A and B):

Each node

i

in

A

encrypts sequence

I

with key

L-key(A,B)

, and it acts as

i

th antenna encoding the encrypted

I

using the MISO encode system. Then, all

m

nodes in

A

broadcast the encrypted and encoded

I

to the nodes in

B

at the same time. When a nodes in

B

receives

m

copies of the information, it decrypts them with

L-key(A,B),

and then decode them back to

I

according to the MISO decode system.

Security Protocol at Network Layer – Key Establishment

Pre-distributed key:

(1) Each node

u

has a pre-distributed key,

pre-key(b,u),

shared with base station

b

. (2) Base station

b

has all keys,

pre-key(b,u)

, for all nodes

u

in the network.

Key Establishment Algorithm:

• •

Step 1.

each head node

u

of cluster

A

sends a key request to base station

b

: {(

u.id, b.id

), encrypted (

u.id, b.id, u.member-list , u.neighbor-list

)} using

pre-key(u,b).

Step 2. b decrypts the key request using

pre-key(u,b)

from all head nodes

u

. Step 3. b generates a cluster key

C-key(A)

for each cluster

A

and a link key

L-key(A,B)

for each link

AB

of the relay backbone and disseminates the keys as follows: for each cluster

A

,

b

sends each node

p

of

A

a cluster key response: {(

b.id, p.id

), encrypted (

b.id, p.id, C-key(A

))} using

pre-key(p,b).

for each link

AB

in the relay backbone,

b

sends each node

p

in

A

a link key response: {(

b.id, p.id

), encrypted (

b.id, p.id, L key(A,B

))} using

pre-key(p,b);

and each node

q

in

B

a link key response {(

b.id, q.id

), encrypted (

b.id, q.id, L-key(A,B

))} using

pre-key(q,b).

B

Base station

b pre-key(u,b) for all nodes u Key request from u:

(

u.id, b.id

) with encrypted (

u.id, b.id, u.member-list ,

)

u.neighbor-list) using pre-key(u,b) L-key(A,B),L-key(A,C),L-Key(A,D)) using pre-key(p,b) A: head: u Pre-key(u,b) Member-list: p,q,r,s Neighbor-list: B,C,D C

Step 4.

Each node

p

decrypts the received message and get the

C-key

and

L-keys D

Compromised Node Detection at Transmission/Physical Layer

A

s



s

1

s

2 ,...,

s

mr

s



s

1

s

2 ,...,

s

mr

B

y

1

h

s



s

1

s

2 ,...,

s

mr

y

3

y

2

Detection Algorithm at head node h Step 1:

Each node of

B y

 (

y

sends the received signal stream to

h

. In other words,

h

1 ,

y

2 ,...,

y

mr )

Step 2:

s

ˆ 

H

estimates the transmitted signal stream by using Inverse Channel Detector:

H -

1

y



s



H

 1  , where

H

is the channel matrix and  is the white Gaussian noise

Step 3:

If the

i s

ˆ

i

th node

x

in

A

is the compromised node.

Network Recovering

Network Recovering Algorithm Step1.

Recovering the data in

B

(1)

h

broadcasts a data discard request:

(h.id)

with encrypted (

h.id, x.id

) using

C-key(A)

(2) Each node in cluster

B

set zero to the column in channel matrix

H

to eliminate the use of the data from

x

Step 2: h sends a detection report to

b:

(

h.id,b.id

) with encrypted (

h.id, b.id, x.id

) using

pre-key(h,b)

Step 3: b sends new

C-key(A)

to each node

p

in

A

except

x:

(

p.id,b.id

) with encrypted (

p.id, b.id, C-key(A)

) with

pre-key(p,b)

Step 4: b send new

L-key(A,B)

to each node

p

in

A

and

B

except

x (p.id,b.id)

with encrypted (

p.id, b.id, L-key(A,B

)) with

pre-key(p,b)

(

p.id, b.id

) with ) with encrypted (

p.id, b.id, L-key(A,B)) using pre-key(p,b)

encrypted (

p.id, b.id, C-key(A)) using pre-key(p,b)

Compromised

A x B h D

Base station

b C

detector

Preliminary Performance Analysis

– Node Detection and Data Recovery

Simulation

 4 cooperative transmission nodes and 4 cooperative reception nodes  Channel: block Rayleigh fading channel  Modulation: binary phase shift keying (BPSK)  Transmission data: 100 symbols  Scenarios: (1) no compromised node (2) one compromised • with no detection • knowing it without • detection with detection

Preliminary Performance Analysis

– Key Management

Scale of the key management system



Types of C-keys

number of the clusters 

Types of L-keys

size of backbone tree 

Number of keys at each node

1 pre-key, 1 C-key,

r

L-key where

r

is the number of neighboring clusters in the backbone 

Number of keys at base station

n

pre-key, where

n

is the number of nodes

Summery and Future work

Summery

A cross-layer security scheme is designed for virtual MIMO networks. • It contains: cryptography based secured communication and routing protocol at • • network layer. compromised node detection at physical layer data and network recovery

Future Work

 Generalize the detection approach to deal with the following cases:  Channel matrix

H

is not square, i.e., the number of cooperative nodes at transmission side is different from that at the reception sides  More than one compromised node  Comprehensive performance evaluation combining the network layer