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.

Authentication by key is successfully applied in many cases. However, this simple approach raises several problems during contextual authentication, when the final decision depends not only on the knowledge of the key but also on some other independent parameters such as time, distance, values fetched from nearby internet of things (IoT) devices, etc. Such contextual parameters are usually considered an independent phase of the whole authentication process. In this paper, we propose a new method of extended authentication because, instead of using just keys, we also applied some mathematical formulas describing the context to be evaluated as a single cryptographic process.

Cryptographic data protection algorithms require specific resources for proper implementation and security. Certain environments, particularly those involving Internet of Things devices, cannot provide the necessary set of measures, including processor speed, memory size, and communication bandwidth, with an acceptable response time and a limitation on battery power consumption. Unfortunately, effective and known data protection mechanisms, such as public key infrastructure, have no potential application in this case. An alternative is to develop other solutions that will ensure an appropriate level of security and will be dedicated to devices with minimal computing and communication resources. This paper proposes a new method to access the resources or to verify access rights using so-called amicable numbers as a base for the authentication mechanism. The mathematical properties of amicable numbers can form the basis for developing new algorithms that are highly needed in the IoT world and relate to fundamental data security and privacy protection issues.