Background: Nowadays, in military and border surveillance application, the WSNs become
an effective part of the command and control system. This requires an efficient type of cryptography.
Due to small size requirement, elliptic curve becomes the most suitable for such purpose.
Objective: The encryption operation, in turn, increases the power required to transmit data through
the network. The aim of this work is to reduce such power.
Methods: This work suggests three methods to reduce the needed power. The first method is
based on spread spectrum technology, which reduces the total number of levels in the network.
The second method deals with algorithm used to choose the sensing node, while the third method
suggests a cost function related directly to the available energy.
Results: Computer simulation tests show a reduction in the required energy by 40% when we apply
the first method, while the second and third methods together reduce the energy by 12% of the
total value of the whole network.
Conclusion: The energy required to transmit encrypted data can be reduced with the aid of routing
algorithms. These algorithm increase the coverage radius of the node transmission.