英语论文网

or in a timely manner. Such attacks can target the communication channel (e.g. jamming) or the life of the nodes themselves (e.g. power exhaustion).

Node Compromise: An embedded device is considered being compromised when an attacker, through various means, gains control or access to the node itself after it is being deployed. These attacks are usually utilized as a foundation for more powerful, damaging attacks.

Side-channel Attacks: An adversary can monitor certain physical properties of the nodes, such as electromagnetic emanation, whenever it performs a cryptographic operation. If the recorded physical values are influenced by the secret key, then the adversary can extract information about that key.

Impersonation Attacks: A malicious sensor node can create multiple fake identities (sybil attack), and also can create duplicates with the same identity (replication attack). These types of attacks are also the initial step which enables the attacker to conduct a wide range of malicious attacks.

Protocol-specific Attacks: Some essential protocols used in WSN, such as routing, aggregation, and time synchronization, are targeted by specific attacks that aim to influence the internal services of the network.

Finally on the basis of the above introduction security in wireless sensor networks are classified as follows

1. The obstacles to the sensor network security

2. The requirement /sources for the WSN

3. Attacks

4. Defensive measures

2.) 无线传感器障碍——OBSTACLES AT SENSOR NETWORK

When compared with traditional computers networks, WSN is special network which has constraints.

2.1) very limited resources:
Data memory, code space energy to the sensor is the resources for the implementation of security in WSN (wireless sensor networks) .These resources are limited in a tiny sensor network

a) limited memory & storage space:

In order to build an effective sensor network security it is necessary to limit the code size as the tiny sensor device has only a little amount of memory and storage space of code. So the code for the security must be small.

b) power consumption:

It is the biggest constraint to WSN as one sensor node deployed in a WSN cannot be easily replaced (i.e. due to high replacement cost). So when implementing a crytopraphic function the power consumption of added security code must be considered.

2.2) Unreliable communication:
It is another threat to the sensor security, as the security of the network depends on the defined protocol in vise versa depends on the communication.

a) Unreliable transfer: A packet based routing is a connectional less and thus inherently unreliable .The unreliable wireless channel also leads to the loss of packets/damages packets .Higher channel rate forces the s/w developer gather resources for the error handling. If the communication channel is unable to handle the error it may lead to the loss of critical security packets (for instance cryptographic key)

b) Conflicts: This occurs in some cases even if the channel may be reliable but due to broadcast nature of the sensor network. In high defense sensor network this may be a major problem.

c) L