Ephemeral Encoding Message in the Elliptic Curve Cryptography for IoT

Wireless Sensor Network (WSN) is a network composed of constrained devices which are limited by their energetic autonomy, computing power and storage capacity. Nevertheless WSNs have demonstrated novel research and developmental interests for military applications. In order to protect the WSN, lightweight and robust cryptographic protocols are needed. Various cryptographic systems were proposed, and most of them are based on public-key algorithms. Elliptic Curve El Gamal (ECEG) is one of the most promising, since it offers a strong protection with smaller sizes of keys. To implement an ECEG cryptographic system, we need to encode the message before encryption and decode it after decryption. In this paper, we propose a new encoding method that improves the ones proposed in the literature. Experimental tests were made and the performances of the new methods are provided.