MATRUSRI ENGINEERING COLLEGE�(An Autonomous Institution)�DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

SUBJECT NAME: WIRELESS SENSOR NETWORKS(PE 518 EC)

FACULTY NAME: Dr. M.NARESH

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LESSON PLAN:

UNIT-V: Security Issues In Wireless Sensor Networks

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INTRODUCTION:��

UNIT-V: Security Issues In Wireless Sensor Networks

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OUTCOMES:

Evaluate concepts of security in sensor networks

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WSNs suffer from many constraints, including low computation capability, small memory, limited energy resources, susceptibility to physical capture, and the use of insecure wireless communication channels. These constraints make security in WSNs a challenge.

CONTENTS:�INTRODUCTION�

OUTCOMES:

To understand concepts of security in sensor networks.

MODULE-I

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CONTENTS:�5.1. SECURITY ARCHITECTURES�5.2. SURVEY OF SECURITY PROTOCOLS FOR WIRELESS SENSOR NETWORKS AND THEIR COMPARISONS����

OUTCOMES

Evaluate concepts of security in sensor networks

UNIT-V: Security Issues In Wireless Sensor Networks

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INTRODUCTION

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Advances in wireless communication and electronics have enabled the development of low-cost, low power, multifunctional sensor nodes.

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These tiny sensor nodes, consisting of sensing, data processing, and communication components, make it possible to deploy Wireless Sensor Networks (WSNs), which represent a significant improvement over traditional wired sensor networks.

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WSNs can greatly simplify system design and operation, as the environment being monitored does not require the communication or energy infrastructure associated with wired networks.

WSNs are expected to be solutions to many applications, such as detecting and tracking the passage of troops and tanks on a battlefield, monitoring environmental pollutants, measuring traffic flows on roads, and tracking the location of personnel in a building.

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Many sensor networks have mission-critical tasks and thus require that security be considered.

INTRODUCTION

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The differences between sensor networks and ad hoc networks are greatly affect how secure data-transfer.

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The limited energy and processing power of nodes makes the use of public key cryptography nearly impossible.

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Public key cryptography might be feasible in sensor networks it remains for the most part infeasible in WSNs most security schemes make use of symmetric key cryptography.

One thing required in either case is the use of keys for secure communication. Managing key distribution is not unique to WSNs, but again constraints such as small memory capacity make centralized keying techniques impossible.

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Straight pair wise key sharing between every two nodes in a network does not scale to large networks with tens of thousands of nodes, as the storage requirements are too high. A security scheme in WSNs must provide efficient key distribution while maintaining the ability for communication between all relevant nodes.

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INTRODUCTION

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In addition to key distribution, secure routing protocols must be considered. These protocols are concerned with how a node sends messages to other nodes or a base station. A key challenge is that of authenticated broadcast.

Existing authenticated broadcast methods often rely on public key cryptography and include high computational overhead making them infeasible in WSNs.

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Secure routing protocols proposed for use in WSNs, such as SPINS , must consider these factors.

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Additionally, the constraint on energy in WSNs leads to the desire for data aggregation. This aggregation of sensor data needs to be secure in order to ensure information integrity and confidentiality.

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While this is achievable through cryptography, an aggregation scheme must take into account the constraints in WSNs and the unique characteristics of the cryptography and routing schemes.

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5.1 Security Architecture

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A WSN is usually composed of hundreds or thousands of sensor nodes. These sensor nodes are often densely deployed in a sensor field and have the capability to collect data and route data back to a base station (BS). A sensor consists of four basic parts: a sensing unit, a processing unit, a transceiver unit, and a power unit . It may also have additional application- dependent components such as a location finding system, power generator, and mobilizer

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5.1 Security Architecture

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The protocol stack used in sensor nodes contains physical, data link, network, transport, and application layers defined as follows [4]:

• Physical layer: responsible for frequency selection, carrier frequency generation, signal deflection, modulation, and data encryption

• Data link layer: responsible for the multiplexing of data streams, data frame detection, medium access, and error control; as well as ensuring reliable point-to-point and point-to-multipoint connections

• Network layer: responsible for specifying the assignment of addresses and how packets are forwarded

• Transport layer: responsible for specifying how the reliable transport of packets will take place

• Application layer: responsible for specifying how the data are requested and provided for both individual sensor nodes and interactions with the end user

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5.1 Security Architecture-Constraints in WSNs

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Constraints in WSNs

Variety of real-life sensor nodes

Individual sensor nodes in a WSN are inherently resource constrained.

They have limited processing capability, storage capacity, and communication bandwidth.

Each of these limitations is due in part to the two greatest constraints — limited energy and physical size.

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5.1 Security Architecture-Constraints in WSNs

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The design of security services in WSNs must consider the hardware constraints of the sensor nodes:

• Energy:

Energy consumption in sensor nodes can be categorized into three parts:

–Energy for the sensor transducer

–Energy for communication among sensor nodes

–Energy for microprocessor computation

Computation:

The embedded processors in sensor nodes are generally not as powerful as those in nodes of a wired or ad hoc network.

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Memory:

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Transmission range:

5.2 Survey of Security protocols for WSN-Security requirements

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The goal of security services in WSNs is to protect the information and resources from attacks and misbehavior.

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The security requirements in WSNs include:

• Availability,
• Authorization
• Authentication
• Confidentiality
• Integrity,
• Non-repudiation
• Freshness

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As new sensors are deployed and old sensors fail, we suggest that forward and backward secrecy should also be considered:

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• Forward secrecy

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• Backward Secrecy

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5.2 Survey of Security protocols for WSN: Threat model

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• In WSNs, it is usually assumed that an attacker may know the security mechanisms that are deployed in a sensor network; they may be able to compromise a node or even physically capture a node.

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• once a node is compromised, the attacker is capable of stealing the key materials contained within that node.

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• Base stations in WSNs are usually regarded as trustworthy.

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Attacks in sensor networks can be classified into the following categories:

• Outsider versus insider attacks:

• Passive versus active attacks:
• Mote-class versus laptop-class attacks:

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5.2 Survey of Security protocols for WSN:Evaluation

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The following metrics to evaluate whether a security scheme is appropriate in WSNs:

• Security:
• Resiliency:
• Energy efficiency:
• Flexibility:
• Scalability:

• Fault-tolerance:
• Self-healing:
• Assurance:

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5.2 Survey of Security protocols for WSN: Attacks in sensor networks

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WSNs are vulnerable to various types of attacks. According to the security requirements in WSNs, these attacks can be categorized as:

• Attacks on secrecy and authentication:
• Attacks on network availability:
• Stealthy attacks against service integrity:

• In these attacks, keeping the sensor network available for its intended use is essential. DoS (Denial-of-service) attacks against WSNs may permit real-world damage to the health and safety of people.

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• The DoS attack usually refers to an adversary’s attempt to disrupt, subvert, or destroy a network However, a DoS attack can be any event that diminishes or eliminates a network’s capacity to perform its expected function.

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• Sensor networks are usually divided into layers, and this layered architecture makes WSNs vulnerable to DoS attacks, as DoS attacks may occur in any layer of a sensor network.

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5.2 Survey of Security protocols for WSN: Attacks in sensor networks

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PHYSICAL LAYER

• Jamming
• Tampering

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LINK LAYER

• Collisions
• Exhaustion
• Unfairness

NETWORK AND ROUTING LAYER: The network and routing layer of sensor networks is usually designed according to the following principles.

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• Power efficiency is an important consideration.

• Sensor networks are mostly data-centric.

• An ideal sensor network has attribute-based addressing

and location awareness.

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5.2 SURVEY OF SECURITY PROTOCOLS FOR WSN :ATTACKS IN SENSOR NETWORKS�

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Sensor network layers and denial-of-service defenses

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5.2 Survey of Security protocols for WSN: Attacks in sensor networks

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The attacks in the network and the routing layer include the following:

• Spoofed, Altered, or Replayed Routing Information
• Selective Forwarding
• Sinkhole
• Sybil
• Wormholes
• Hello Flood Attacks
• Acknowledgment Spoofing

TRANSPORT LAYER:

• Flooding
• De-synchronization

CONTENTS:�5.2 SURVEY OF SECURITY PROTOCOLS FOR WSN: CRYPTOGRAPHY IN WSNS�� �

OUTCOMES:

Discuss about survey of security protocols of WSNs

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MODULE-3

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5.2 Survey of Security protocols for WSN: Cryptography in WSNs

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• Selecting the most appropriate cryptographic method is vital in WSNs because all security services are ensured by cryptography.

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• Cryptographic methods used in WSNs should meet the constraints of sensor nodes and be evaluated
• by code Size,
• Data size,
• Processing time, and
• Power consumption

• Public key cryptography,

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• Symmetric key cryptography.

Public key cryptography: average ECC

and RSA execution times

Public key cryptography: average energy costs of digital signature and

key exchange omputations

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5.2 Survey of Security protocols for WS: Cryptography

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Symmetric key cryptography: average

RC5 and skipjack execution times

Symmetric key cryptography: average

energy numbers for AES and SHA-1

Tables shows the execution time and

energy cost of two symmetric cryptography protocols on an

Atmel ATmega128 processor

The performance of symmetric key cryptography is mainly decided by the following factors:

• Embedded data bus width

• Instruction set

5.2 Survey of Security protocols for WSN : Key management protocols

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Key management is a core mechanism to ensure the security of network services and applications in WSNs. The goal of key management is to establish required keys between sensor nodes which must exchange data.

According to the network structure, the protocol scan be divided into centralized key schemes and distributed

key schemes.

Taxonomy of key management protocols in WSNs

5.3 Classification and comparison of key management protocols in WSNs

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5.2 Survey of Security protocols for WSN :Secure routing protocols

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Many routing protocols have been specifically designed for WSNs. These routing protocols can be divided into three categories according to the network structure:

• flat-based routing,
• hierarchical-based routing, and
• location-based routing

In flat-based routing, all nodes are typically assigned equal roles or functionality.

In hierarchical-based routing, nodes play different roles in the network.

In location-based routing, sensor node positions are used to route data in the network.

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Most network layer attacks against sensor networks fall into one of the categories described above, namely:

• Spoofed, altered, or replayed routing information • Wormholes

• Selective forwarding • Sybil

• Sinkhole • Acknowledgment spoofing

• Hello flood attacks

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5.2 Survey of Security protocols for WSN :Secure routing protocols

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A secure routing protocol depends on an appropriate key management scheme in a WSN, which has been discussed earlier.

Before a routing protocol starts, sensor nodes should have been loaded with proper keys (e.g., the key for confidentiality, authentication, etc.). One of the fundamental security services in sensor networks is broadcast authentication, which enables the base station to broadcast authenticated data to the entire sensor network.

Using a time-released key chain for source authentication

Broadcast authentication

Authenticated broadcast are impractical

in WSNs for the following reasons:

• Most proposals rely on public key cryptography for the

authentication. However, public key cryptography is

impractical for WSNs;

• Even one-time signature schemes that are based on symmetric

key cryptography have too much overhead.

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5.2 Survey of Security protocols for WSN :Secure routing protocols

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Secure routing

The goal of a secure routing protocol is to ensure the integrity, authentication, and availability of messages.

SNEP offers the following properties:

• semantic security,
• data authentication,
• replay protection,
• weak freshness, and
• low communication overhead.

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5.2 Survey of Security protocols for WSN :Secure routing protocols

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Comparison of secure routing protocols

SPINS identifies two types of freshness:

weak freshness and strong freshness.

Weak freshness provides partial message ordering and carries no delay information while strong freshness provides a total order on a request–response pair and allows for delay estimation.

5.2 Survey of Security protocols for WSN : Secure data aggregation

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Secure data aggregation in WSNs:

Data aggregation (fusion) protocols aim at eliminating redundant data transmitted across the network and are essential for energy-constrained WSNs.

Traditional data aggregation techniques include simple types of queries such as SUM, COUNT, AVERAGE, and MIN/MAX.

According to the protocol operation, secure

data aggregation can be classified into two categories:

Plaintext based and

Cipher based

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Assignment Question

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1. Explain the Hardware components of Security Architecture
2. Classification and comparison of key management protocols in WSNs.
3. What are the Security Routing Protocols.
4. Discuss about Cryptography in WSNs.
5. What are the Design constraints of security services in WSNs

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Questions & Answers

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Short answer questions

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Questions & Answers

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Long answer questions