1. Wireless sensor
network
Presented by:
Bhanoori, Abilash
Castaneda, Michael
Kumarasamy, MalarKaviya
Shah, Tosha
Shekhawat, Hitendra

2. What are Wireless Sensor
Networks(WSN)?
●A network of spatially distributed autonomous
sensor nodes to monitor certain physical or
environmental conditions or application specific
events.
●Components of the network are connected
through wireless connections.

3. WSN Architecture
●Wireless sensor networks are widespread and
are used in diverse application areas such as
military, education, monitoring, retail, science
etc.
●In order to design such a network many issues
such as network design, data compression,
security parameters etc. need to be considered
and analyzed.
●The design requirements of a wireless sensor
network are dependent on the application for
which these networks are established.

4. WSN Architecture
(Cont.)

5. Components of WSN
Processors/Controllers:
The processor is the central unit of the system,
which performs tasks; processes the data
presented to it and also control the functions of
the other components of the network system.
Transceiver:
Transceivers are nothing but the combination of
both the transmitters and receiver involved in
sensor networks to facilitate communication.

6. Components of WSN (Cont.)
Storage devices:
Depending on the overall sensor network
structure or application requirement, the
requirements for storage like whether it should be
fast or nonvolatile memory can be sharply
different. Most of the sensor networks prefer flash
memory because of their advantages in terms of
cost and storage capacity.

7. Components of WSN (Cont.)
Power source:
●Equip each sensor node with a (rechargeable)
source of energy.
●Harvest energy from the environment.
Sensors:
Sensors are hardware devices that are
responsible to respond to any change in a
physical condition or occurrence of any
predefined event. Sensors capture and measure
the event needs to be monitored. The data
captured is then sent to controllers for further
processing.

8. Goals of WSN Design
●Small physical size: physical size reduction
has always been challenging and favorable. All
the components of a sensor network are
reduced as possible in size suitable to the
application.
●Lower power consumption: The capability
and performance of the sensors are dependent
on energy supply. Since maintenance of
sensor nodes are expensive, sensor must be
made active for a reasonable time without
recharging.

9. Goals of WSN Design (cont.)
●Diversity in design and usage: design of
sensor network is application dependent. All
the features like small size, low power
consumption and efficiency etc cannot be
implemented together. There is always a
tradeoff between reuse, cost and efficiency.
●Robust operation: sensors are expected to be
fault and error tolerant and so the sensors
should be able to self-test, self-calibrate and
self-repair.

10. Goals of WSN Design (Cont.)
●Security and Privacy: Each sensor should be
equipped with security mechanism to protect
from unauthorized access, security attacks and
modification of system’s critical information.
●Compatibility: The components developed for
the wireless sensor networks must be
compatible with each other.
●Flexibility and scalability: The network must
accommodate functional and timing changes.
The system can be made flexible by making

11. Goals of WSN Design (cont.)
●Network connectivity and QoS : Connectivity
of the network is very important in Wireless
sensor networks. Few isolated sensor nodes in
the network can cause missing or delay of
mission critical information. Some self-
organized algorithms should be implemented
to guarantee network connectivity.

12. Features in WSN Design
Network design:
●single-tier networks architecture of
homogeneous sensor
●single-tiered clustered architecture of
heterogeneous sensors
●multi-tiered network architecture of
heterogeneous sensors

13. Features in WSN Design (Cont.)

14. Information flow:
There are 3 types of information flow in WSNs.
The first type is one-way communication from
sensors to the sink or the gateway. The second
type is two-way information flow which can
manage sensor nodes by sending control
message from the sink to sensor nodes. The last
type is multi-way information flow which can be
applied to multi-media applications.
Data compression:
Bandwidth for wireless sensor network is very
scarce and expensive. Every application or
methodology tries to effectively utilize the
available bandwidth. Data compression is one of

15. Communication Patterns of WSN
●Many to one: Multiple sensor sends
data to base station.
●One to Many: Single sensor node
multicasts message to several
sensor node.
●Local communication: Sensor
communicates between each

16. Security Requirements
●Data Authenticity
●Data Confidentiality: Encryption
●Data Integrity: Harsh environment
conditions
●Data Freshness: No old message have
been sent over the network
●Robustness: Compromise of a single node
should not break the security of entire network
●Availability

17. Key Management
●Dynamically establish and maintain
secure channels among
communicating nodes
●Primary challenge:
 Managing the trade-off between providing
acceptable levels of security and
conserving scare resources
●Desired features of Key
management in WSN:
 Energy awareness

18. Key Management Schemes
●Diffie – Hellman and public key
based schemes are not suitable for
WSN
●Pre- distribution of secret keys for
all the pairs of nodes is not viable
due to large amount of memory
used when the network size is
large.
●Random key predistribution

19. Basic functions of Key
Management

20. ●Key Analysis:
 Key requirements of the network nodes
are analyzed
 Determine whether keys needs to be
updated using input from a detection
system
●Key Assignment:
 Mapping of keys to different parties
 Communication keys are simply assigned
by agreement of parties wanting to
establish secure communication channel
 It can be static and dynamic
 Mapping decision significantly impact the

21. ●Key Generation:
 Generation of administrative keys may
take place once or multiple times over the
lifespan of the network.
 Communicating parties are generating the
communication keys
 Key generating nodes must be trusted by
all key –receiving nodes.
 Keys might be as simple as a bit string or
as complex as a symmetrical bivariate
polynomial

22. ●Key distribution (and redistribution)
 Delivery of keys to their designated nodes
after they have been generated and
assigned to the nodes.
 Distribution of communication keys
usually takes place after the network has
been deployed
 Communication keys are used for a short
period of time and should be regularly
updated.

23. Security in a Wireless Sensor
Network vs.
Ad-hoc Networks
●Hardware Limitations
oProcessing Limitations
oMemory Limitations
oEnergy Constraints
oCommunication Constraints
●Dense Deployment
oDifficult to service

24. Vulnerabilities in a WSN
●Physical Tampering
●Physical Layer Attacks
●Link Layer Attacks
●Network and Routing Layer Attacks
●Transport Layer Attacks
●Traffic Analysis Attacks
●Key Management Attacks
●Attacks on Reputation-Assignment
Schemes

25. Threat Models
●Mote-Class vs Laptop-Class
Adversaries
●Insider vs Outsider Adversaries
●Passive vs Active Adversaries

26. Uncompromised WSN

27. Physical Tampering
●Non-Invasive Attacks
oTiming Attack
 Monitoring Execution Speed can reveal
confidential data
●Invasive Attacks
oBlock Cipher Attack
 Obtain bit values through power analysis
techniques. Since most WSN protocols use
symmetric key encryption, crypto-analysis
techniques can be used on authentication codes to
decipher messages.

28. Resistance for Physical Mote
Attack
●Cryptoprocessors are physically secure
processors that have been used extensively to
provide some level of physical tamper
resistance.
●A secure cryptoprocessor is a dedicated
computer on a chip or microprocessor for
carrying out cryptographic operations,
embedded in a packaging with multiple
physical security measures, which give it a
degree of tamper resistance.

29. Defense for Block
Cipher/Timing Attacks
●Randomization based blinding function –
basically adding random number to be exponential with
encryption exponent before cipher text decryption.
●Equalizations based blinding function-
dummy operations are added to make same operation
from cipher text data or related information parameter.
●Quantization based blinding function –
The computation take exponent time of the quantum
decided.

30. Link Layer Attacks
●Jamming Attacks
oMore powerful transmitter purposely causes
interference.
●Exhaustion Attacks
oRepeatedly sending transmissions with the
intention of exhausting a victim node’s
resources.
●Unfairness Attacks
oUsing a more powerful transmitter to send
messages over a particular wireless channel
shared by other nodes. Therefore preventing
other nodes from communicating to the

31. Jamming attack solution
Repeated inability to access wireless channel
• Bad framing
• Checksum failures
• Illegal values for addresses or other fields
• Protocol violations (e.g., missing ACKs)
• Excessive received signal level
• Low signal-to-noise ratio
• Repeated collisions
• Duration of condition

32. ●Check or keep track of packets
from same source and same data
also frequency
●And in future step we might have
denial of service for specifically that
kind of message or message from
same source.
Exhaustion Attack Solution

33. Unfairness Attack Solution
●Solution is not prioritizing any one
of the channel.
oRandom channel selection to listen on
from all available connection.
oAs defense assigning variable counter
attached to the wireless nodes that
keep track of same connection
established.
●Threshold is just a matter of choice as
per the application, but this method also

34. Network and Routing Layer
Attacks
●Sinkhole or Black Hole Attacks
oRoute all nearby traffic through a
compromised or malicious node.
oAdversary can gather transmission data or
prevent data from reaching the base station

35. Sinkhole Attack

36. Sinkhole Defense and
Countermeasure
●Dynamic Trust Management
System (DTMS), which measures
that the packets arrive safely at the
base station and distributes trust to
all nodes.

37. Network and Routing Layer
Attacks
●Wormhole Attacks
oImplement a Sinkhole Attack
oTunnel messages from one part of the
network to another
oBreaks localization protocols
oCan monitor a large amount of traffic

38. Wormhole Attack

39. Wormhole Defense and
Countermeasures
●The goal is to verify the existence
of a direct link to an apparent
neighbor using timing and
authentication and also to get
Geographic routing protocols

40. Network and Routing Layer
Attacks
●Spoofing Attacks
oMasquerade as a node or base station by
modifying Routing information in replayed
packets
oCan cause misdirection, attract/repel traffic,
generate false messages, partition networks,
increase latency.

41. Spoofing Attack

42. Spoofing Defense and
Countermeasure
●Filter incoming packets that appear
to come from an internal IP
address at your perimeter.
●Filter outgoing packets that appear
to originate from an invalid local IP
address.

43. Network and Routing Layer
Attacks
●Hello Flooding Attacks
oAn adversary with a more power transmitter
(such as a laptop class attacker) , sends a
Hello packet to all nodes within range
advertising a high quality route. Nodes that
attempt to reply may not be in range.
oAffects protocols that assume Hello packets
are sent only between nodes within
transmitter range.

44. Hello Flooding Attack

45. HELLO Flood Defense and
Countermeasure
●Certify the bi-directionality of link.
●Attach identity verification for
authentication.
●Though it has overhead for
verifying and authenticity checking
but it is worth overhead in
comparison of attack.

46. Transport Layer Attacks
●Flooding Attacks
oAn adversary floods a victim node with
connection requests, thereby exhausting the
node’s memory.
●Desynchronization Attacks
oAn adversary modifies the sequence number
in an intercepted transmission. The receiver
finds that the sequence number is
inconsistent and requests that the packet be
resent.
oCan be used to cause an infinite loop.

47. Reputation Assignment
Scheme Attacks
●Ballot Stuffing Attacks
oAn adversary manipulates the outcome of a
vote by creating a large number of falsified
entries.
●Bad Mouthing Attacks
oMalicious nodes accuse a legitimate node of
malicious behavior, therefore causing the
legitimate node to be taken offline.

48. Attacks on In-Network
Processing
●What is an aggregation node and why is
it used?
oAggregation nodes collect information from
nearby nodes and use this information to
calculate an aggregate.
oThis protocol requires much fewer
transmissions therefore significantly
reducing energy consumption.

49. Attacks on In-Network
Processing
●Aggregation Attacks
oAn aggregation node is captured or spoofed.
oThe aggregate is manipulated therefore
causing a much more significant impact on
the total result.

50. In-Network Processing
Defense and
Countermeasure
●Prevent adversary from spoofing
the aggregate adversary node.
●More security is needed for the
aggregate nodes.

51. Sybil Attacks
●A single piece of hardware masquerades
as many nodes.
●Can be used to distribute blame or dilute
suspicion in reputation-assignment
schemes.
●Can have a greater impact on routing by
appearing at more than 1 location.
●Can be used to corrupt or gather data
from distributed storage systems.
●Can have a greater impact on data
aggregation

52. Sybil Attack

53. Defense against node
Replication Attacks
●Localized Multicast.
oIt randomly selects witnesses for
nodes containing its ID and location
within a geographically limited region
(referred to as cell).

54. Countermeasures for Sybil
Attacks
●Key to counter is to validate that each
node identity is the only identity
presented by the corresponding physical
node.
●Direct validation - Node directly tests
whether another node identity is valid.
●Indirect validation - Nodesthathave already
been verified are allowed to vouch for or refute
other nodes. With the exception of the key pool
defense, the mechanisms that we present here
are for direct validation.

55. Previous Measures
●Resource testing is a strong candidate
for direct validation
●Physical entities are to be tested proving
that each tested resource as physical
device. But this kind of testing requires
lot of computation and storage, which is
highly unsuitable for wireless networks.
The propose method communication is
to broadcast a request for identities and
then only accept replies that occur within

56. New Defenses
Radio Resource Testing

57. New Defenses
Radio Resource Testing

58. New Defenses
Radio Resource Testing

59. Routing in WSNs
●What is routing?
Process of sending desired packets from source to
destination
●Inherent Characteristics of WSNs
1.High over head maintenance of ID.
2.Sensor nodes are tightly constrained in terms of energy,
processing hence requires careful resource
management.
3.In some cases nodes are free to move which results in
unpredictable and frequent topological changes.
4.Data Redundancy.

60. Cont.…
●Routing challenges and Design Issues
1.Node Deployment
2.Energy consumption with out losing accuracy
3.Quality of service
●Common attacks on Routing Protocols
4.Routing table over flow
5.Routing table poisoning
6.Routing cache poisoning
7.Packet Replication

61. Routing Protocols
Network based protocols
●Flat routing protocols
1.Sensor protocols for information via
negotiation(SPIN)
They are family of adaptive protocols that disseminate the
information at each node to every node in the network assuming
that nodes in the network are potential base stations. These nodes
make use of the property that nodes in close proximity have
similar data which enables the need to only distribute the data that
other nodes don’t possess.
1.Directed Diffusion
Main objective of directed diffusion is to combine data coming from
different sources enroute by eliminating redundancy ,minimizing
the number of transmissions thus saving energy and prolonging

62. Cont.…
Hierarchical Routing Protocols
1.Low Energy Adaptive Clustering
Hierarchy(LEACH)
Leach is a cluster based protocol which selects few sensor nodes
as cluster heads and rotates this role to evenly distribute the
energy load among the sensors in the network.
1.Sensor aggregates routing
Main objective of this protocol is to collectively monitor target
activity in a certain environment. A sensor aggregates those nodes
in a network that satisfies a grouping predicate for a collaborative
processing task.

63. Cont.…
Location Based Routing Protocols
1.Geographic adaptive fidelity (GEF)
Network area is first divided into fixed zones and forms a virtual
grid. Inside each zone nodes collaborate with each other to play
different roles.
1.Geographic and Energy aware routing (GEAR)
GEAR basically uses energy aware and geographically informed
neighbor selection heuristics to route the packets towards the
destination region. The key idea is to restrict the number of
interests by considering to a certain region rather than sending it
to whole Network.

64. Cont.…
Routing protocols based on protocol
operation
1.Negotiation based routing protocol
These protocols use high level data descriptors in order to
eliminated redundant data transmission through negotiation.
Communication decisions are taken based on the resources
available to them. E.g. SPIN.
1.QoS-based routing
In QoS-based routing protocols, the network has to balance
between between energy consumption and data quality. In
particular, the network has to satisfy certain QoS metrics, e.g.
delay, energy, bandwidth when delivering to BS.

65. Conclusion
●Wireless Sensor networks today can be utilized across
many different areas in the society. Hence with this
versatility and capability come various threats and
vulnerabilities.
●One of the most pivotal yet a difficult challenge would be
creating a balance between security and optimality.

66. QUESTIONS?
Thank You