  Aerial drones are becoming an integral part of application domains including
but not limited to, military operations, package delivery, construction,
monitoring and search/rescue operations. It is critical to ensure the cyber
security of networked aerial drone systems in these applications. Standard
cryptographic services can be deployed to provide basic security services;
however, they have been shown to be inefficient in terms of energy and time
consumption, especially for small aerial drones with resource-limited
processors. Therefore, there is a significant need for an efficient
cryptographic framework that can meet the requirements of small aerial drones.
  We propose an improved cryptographic framework for small aerial drones, which
offers significant energy efficiency and speed advantages over standard
cryptographic techniques. (i) We create (to the best of our knowledge) the
first optimized public key infrastructure (PKI) based framework for small
aerial drones, which provides energy efficient techniques by harnessing special
precomputation methods and optimized elliptic curves. (ii) We also integrate
recent light-weight symmetric primitives into our PKI techniques to provide a
full-fledged cryptographic framework. (iii) We implemented standard
counterparts and our proposed techniques on an actual small aerial drone
(Crazyflie 2.0), and provided an in-depth energy analysis. Our experiments
showed that our improved cryptographic framework achieves up to 35x lower
energy consumption than its standard counterpart.
