1 secure cooperative mimo communications under active compromised nodes liang hong, mckenzie mcneal...

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Secure Cooperative MIMO Communications Under

Active Compromised Nodes

Liang Hong, McKenzie McNeal III, Wei Chen

College of Engineering, Technology, and Computer ScienceTennessee State University

Dr. Liang [email protected]

(615) 963-5364


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Outline

• Introduction• System Model• Compromised Nodes Detection and Symbol Recovery• Cooperative Transmission and Security Key

Management Schemes• Simulations• Conclusions

Secure cooperative MIMO communications under active compromised nodes


(615) 963-5364College of Engineering, Technology, and Computer ScienceTennessee State University

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Introduction• Wireless sensor networks (WSNs) have been widely deployed in

− Military sensing and tracking, environment monitoring, smart home appliances

management, health care, etc

− WSNs are expected to be the basic building block of pervasive computing

• Cooperative MIMO can achieve the benefits of MIMO technique

without the need of multiple antennas at each sensor node

− MIMO can provide significant increases in data rate and link range without

additional bandwidth or transmission power

− Physical implementation of multiple antenna at a small node is not feasible

− Distributed individual single-antenna nodes cooperating on data transmission

and reception as a multi-antenna MIMO node




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• Many WSNs have mission-critical tasks, however, the

involvement of multiple nodes for transmission and/or

receiving poses a challenge to the reliability of the information

• Node compromise is one of the most detrimental attacks

− Active attack: the compromised nodes maliciously modify the relay

information and inject falsified information (more severe than passive

attacks)

• Previous security schemes either did not detect and defend

against node compromise or needed extra MIMO antennas to

achieve data assurance.




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• Our previous work proposed a cross-layer security scheme that

combined a cryptographic technique implemented in higher

layer with data assurance analysis at the physical layer

− Has much less bit errors

− Receiving cluster periodically detects compromised nodes

− The transmitting and receiving cluster have equal numbers of nodes

− Only one compromised node is present in the transmitting cluster

− No compromised node is present in the receiving cluster


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Develop compromised node detection algorithm for more general scenarios.

Research objectives



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System Model

Multi-hop cooperative MIMO system


(615) 963-5364

Cooperative strategy: decode-and-forward



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(1)

Received signal

: received signals at the receiving cluster

: additive Gaussian noise components, they are identically distributed and mutually statistically independent, each with a zero mean and a power spectral density


(615) 963-5364

02N

wHsy

TmR

yyy ],,,[ 21 y

TmT

sss ],,,[ 21 s : transmitted signals at the transmitting cluster

H : channel matrix (mRmT)

TmR

www ],,,[ 21 w



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Compromised Nodes Detection and Symbol Recovery


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Methodology:• The CH h of B will perform compromised nodes detection at random

time t in each time interval with adaptive security level



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Compromised nodes detection algorithm 1. The CH h of B requests each of the primary nodes in B to send the

received symbols to h. Then h obtained the combined signal

2. Node h uses Inverse Channel Detector to estimate the transmitted symbols s, i.e., , where W is an mRmT weighing matrix

3. Since all data streams are the same, h can identify the compromised node x if x didn’t transmit the supposed symbol.

– For example, assuming that the primary node x in A is compromised and it is the jth node in A, if sj from step 2 is not the same as the information recovered from the majority of the other nodes, x will be classified as a compromised node

yWs Hˆ



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Scenario 1: The transmitting and receiving clusters have different number of nodes

(2)HHH HHHW 1)(

Scenario 2: More than one compromised node is present in the transmitting cluster

• In step 3, the recovered data streams from different transmitting nodes will be sorted into groups, where nodes are assigned to the same group if they contain identical symbols.

− The group with largest number of nodes is assumed to contain the IDs of trustworthy nodes. All the other nodes are classified as compromised nodes.

− If all the groups have the same number of IDs, all the nodes in transmitting cluster are classified as compromised nodes.



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Scenario 3: Compromised nodes are present in the receiving cluster

1. The CH h in B performs inverse channel detection on the set of received data from each node in B.

2. If two or more of the estimates of the transmitted symbols are the same, then this node in B is not compromised. Its ID will be saved in the trustworthy node group.

3. If none of the estimates of the transmitted symbols are the same, then this node in B is the compromised node.

4. After all the compromised nodes in B are identified, all the trustworthy nodes in B will be used to identify the compromised nodes in A. Using the algorithm in Scenario 2, the compromised nodes in A can be detected



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Symbol recovery:• When the compromised nodes are detected in the transmitting cluster

− the CH h in B will send each node in its cluster the information of the compromised nodes in A.

− When the node v in B receives this information, it decodes the message by simply setting the columns in channel matrix that corresponds to the compromised nodes to zero

• When the compromised nodes are detected in the receiving cluster

− The CH h in B will send the IDs of the trustworthy nodes to the CH in its next relay.

− In the next relay, simply setting the column in channel matrix that corresponds to these compromised nodes to zero.

− If compromised nodes are detected in the last receiving cluster, the sink node will use the received data from the trustworthy nodes for symbol detection



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Cooperative Transmission and Security Key Management Schemes

• The cooperative transmission and security key management schemes proposed in our previous work will be used to provide secure cooperative communications.

• This security scheme provides secured communication between uncompromised nodes.

• By combining the compromised nodes detection algorithm, the security of the system will be largely enhanced.




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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 in A encrypts its information with C-key(A),

and broadcasts it to other local nodes using different timeslots. Each node uses C-key(A) to decrypt the received m information back.

Step 2 (long-haul transmission between A and B): Each node i in A encrypts sequence I with key L-key(A,B), and it acts as ith antenna encoding the encrypted I. 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.



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Simulations

• The channels are block Rayleigh fading channels. • It is constant during the transmission of one symbol, but is randomly

changing between symbols• Different channels are identically distributed and statistically

independent. • Binary phase shift keying (BPSK) is chosen as the modulation

scheme. • 100 received symbols are used in the proposed algorithms for

compromised nodes identification. • The maximum likelihood detector is used for symbol

demodulation




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For scenario 1 and 2

Detection Accuracy Performance Comparison



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For scenario 1 and 3

Detection Accuracy Performance Comparison



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Conclusions

• Algorithms for compromised nodes detection are proposed for three more general scenarios.

• The proposed compromised nodes detector are then used in a cooperative MIMO communication system to enhance the security.

• The compromised nodes detector has high detection accuracy.

• The reliability of the information is significantly improved.




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Thank you!

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1 secure cooperative mimo communications under active compromised nodes liang hong, mckenzie mcneal...

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