In this paper, the secure low-power Internet of Things (IoT) transmission methods for encryption and digital signature are presented. The main goal was to develop energyefficient method to provide IoT devices with data confidentiality, integrity, and authenticity. The cryptograph energy efficient and security algorithms modifications for IoT domain were made. The novelty in our solution is the usage of encryption method popular in the image processing in the domain of the Internet of Things. Proposed modification improves immunity for the brute-force and plain-text attacks. Furthermore, we propose the modifications for hash calculation method to transform it into digital signature calculation method that is very sensitive to input parameters. The results indicate low energy consumption of both methods, however it varies significantly depending on the architecture of the devices.

The smart grid concept is predicated upon the pervasive With the construction and development of distribution automation, distributed power supply needs to be comprehensively considered in reactive power optimization as a supplement to reactive power. The traditional reactive power optimization of a distribution network cannot meet the requirements of an active distribution network (ADN), so the Improved Grey Wolf Optimizer (IGWO) is proposed to solve the reactive power optimization problem of the ADN, which can improve the convergence speed of the conventional GWO by changing the level of exploration and development. In addition, a weighted distance strategy is employed in the proposed IGWO to overcome the shortcomings of the conventional GWO. Aiming at the problem that reactive power optimization of an ADN is non-linear and non-convex optimization, a convex model of reactive power optimization of the ADN is proposed, and tested on IEEE33 nodes and IEEE69 nodes, which verifies the effectiveness of the proposed model. Finally, the experimental results verify that the proposed IGWO runs faster and converges more accurately than the GWO.