29-12-2009, 06:45 PM
Wireless Sensor Networks
A wireless sensor network consists of large Number Of Nodes.Large number of heterogeneous Sensor devices spread over a large field.They perform Wireless sensing and Data Networking. Group of sensors linked by wireless media to perform distributed sensing tasks
Each node has three components: sensing, processing, and communication. Networked sensors can continue to operate accurately in face of failure of individual sensors.Each sensor node operates autonomously with no central point of control in the network. Each node bases its decision on its mission.
SPIN: Sensor Protocols for Information Negotiation
It is one of the most dominant form of routing in the wireless sensor networks.The SPIN protocol names the data using data descriptors or meta data.The nodes use meta data negotiations to eliminate transmission of redundant data in the network. SPIN nodes can base their communication decisions on knowledge of data and resources allowing them to distribute data given limited energy supply.
Advantages of SPIN
negotiation
-SPIN nodes negotiate with each other before transmitting data. This ensures that only the useful information is transferred.
-SPIN uses descriptors called meta data
-Redundant data messages are not sent
-Nodes are able to name the portion of data they are interested in obtaining.
Resource adaptation
-The wireless sensor network nodes poll their resources before data transmission
-Each sensor node had its own resource manager that keeps track of resource consumption
-Nodes are aware of their local energy resources and this enables them to reduce their activities when their energy resources are low
-Nodes monitor and adapt to changes in their own energy resources and thus extend the operating lifetime of the system
SPINS: Security Protocols for Sensor Networks
With thousands to millions of small sensors form self-organizing wireless networks in the future, providing security for these sensor networks is a big issue.
SPINS has two secure building blocks: SNEP(Secure Network Encryption
Protocol) and microTESLA((the micro version of the Timed, Efficient, Streaming, Loss-tolerant Authentication Protocol). SNEP provides the following : Data confidentiality, two-party data authentication, and data freshness. microTESLA provides authenticated broadcast for severely resource-constrained environments.
SPINS SECURITY BUILDING BLOCKS
SNEP:
This provides Data Confidentiality, Authentication, Integrity, and Freshness.
- it has low communication overhead as it adds only 8 bytes per message.The counter state is kept at each end point and does not need to be sent in each message.
-it uses a counter, but avoids transmitting the counter value by keeping state at both
end points.
- It achieves semantic security which prevents eavesdroppers from inferring the
message content from the encrypted message.
- This protocol also provides data authentication, replay protection, and weak message freshness.
To achieve two-party authentication and data integrity, a message authentication code (MAC) is used.
Data authentication: If the MAC(message authentication code) verifies correctly, a receiver
can be assured that the message originated from the claimed sender.
Replay protection: The counter value in the MAC prevents replaying old messages.
Semantic security: the same message is encrypted differently each time.
Weak freshness: If the message verified correctly, a receiver
knows that the message must have been sent after the previous
message it received correctly. Thus it achieves weak freshness.
microTESLA
microTESLA overcomes introduces asymmetry through a delayed disclosure of symmetric
keys, which results in an efficient broadcast authentication
scheme. It requires that the base station and nodes are loosely
time synchronized, and each node knows an upper bound on the
maximum synchronization error. To send an authenticated packet of data,
the base station computes a MAC on the packet with a key
that is secret at that particular point in time. When a node gets a packet, it can
verify that the corresponding MAC key was not yet disclosed by
the base station. Since a receiving node is assured that the MAC key
is known only by the base station, the receiving node is assured that the data was not modified during the sending process. If the key is correct, the node can
now use it to authenticate the packet stored in its buffer.
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