Energy efficient secure pattern based data aggregation for wireless sensor networks

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This paper discusses about a data aggregation protocol to decrease redundancy and hence increase bandwidth efficiency. This protocol is called: ESPDA: Energy Efficient Secure Pattern based Data Aggregation. This protocol eliminates redundancy by making all nodes with the same data sleep except for one. It is secured since cluster-head in this method do not need to know about sensor node’s data(the cluster head is in charge of broadcasting within the cluster). Hence sensor node sends encrypted data via the cluster-head to the base station and by establishing a secure end to end communication. This is the first protocol providing both security and aggregation together.
Finally it provides simulation results with C and using GloMoSim. Working on efficient generation of pattern codes is mentioned as future work.

Q: How does it do aggregation?
A: by using pattern code. Each node gathers data from all its sensing units, Makes a pattern code and sends it to cluster head. The cluster head gets all patterns from all its nodes and decides which node to sense data and send it. Then other nodes sleep.

Q: What is a pattern code?
A: A pattern code is made based on the main ideas of observed object. E.g. if the observed object is a picture of a human, the main recognition parameters for human is considered to create pattern code.

Q: How the Cluster head determines the best pattern code?
A: It has a sense of distinct pattern code based on the object being observed.

Q: How doesn’t the cluster head need to know about data sent by sensor node?
A: It only examines pattern codes and after that does not observe any data from the determined sensor node.

Q: How sensor node encrypts data without exchanging a key with base via cluster head?
A: each node has an id and also a secret key. Base station has a database of all ids and their secret keys. And this database is made in manufacturing phase. When a node sends information it sends its id also. Hence Base can decrypt data. To have a better security and ensure freshness, base broadcasts a common key named Kb in the network. All nodes XOR their secret key with Kb and hereafter use this new key.

Q: Encrypting algorithms needs process and consumes a high amount of energy. How is it energy efficient while using encryption?
A: It employs symmetric key cryptographic algorithms to ensure energy efficiency.