Modern, commonly used cryptosystems based on encryption keys require that the length of the stream of encrypted data is approximately the length of the key or longer. In practice, this approach unnecessarily complicates strong encryption of very short messages commonly used for example in ultra-low-power and resource-constrained wireless network sensor nodes based on microcontrollers (MCUs). In such cases, the data payload can be as short as a few bits of data while the typical length of the key is several hundred bits or more. The article proposes an idea of employing a complex of two algorithms, initially applied for data compression, acting as a standard-length encryption key algorithm to increase the transmission security of very short data sequences, even as short as one or a few bytes. In this article, we present and evaluate an approach that uses LZW and Huffman coding to achieve data transmission obfuscation and a basic level of security.

In this paper we propose a new approach to complex comfort management based on ontologies, being the main result of undergoing GOLIATH project. The approach comprises an application of Internet-of-Things (IoT) devices, an abstraction layer (SITE), a smart IoT middleware and a Multi-Agent System (MAS). Those elements allow a user to ask the system in a simple and natural way to control one or more comfort elements (including temperature, humidity, luminosity, noise, ventilation and air quality). Shared knowledge fed by the IoT and its semantic environment (SITE) will be used by smart layers (Knowledge base and MAS) to reason and propose an action on one or more IoT devices in turn managed by SITE. The implementation is based on underlying ontologies of comfort and actions and real-world objects connected with IoT devices, as well as a dedicated Context-Aware System to deal with dynamic situation, time/place of an interaction, evolving requirements, etc.

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