Audio steganography is the process of hiding a message inside an audio container. This study aims to present a systematic review of audio steganography methods. Existing reviews of audio steganography suffer from a high overlap or a low segregation level among the methods reviewed due to poor classification criteria. These articles are also lacking in terms of depth of analysis and the number of articles reviewed. The data collection method includes surveying five databases, namely, Web of Science, IEEE Explore, ScienceDirect, Scopus, and Springer, resulting in a total of 134 articles. The review focuses on the embedding process of each method. The methods can be classified into several categories based on the most prominent idea in the embedding process; hence, a new classification is proposed. The proposed classification provides a scope for summarizing and understanding the most followed approaches in audio steganography. This study then critically reviews the strengths and weaknesses of each method on the basis of its embedding behavior. Other issues on the domain of embedding, carrier types, and evaluation environments are also discussed.

IoT testbed has been continuously on the rise in line with the significant advances of technology in sensor network to provide real-world interconnection. Researchers have developed numerous testbeds for IoT applications with many unique innovations. However, there is still a missing element in the testbed analysis on the security services and its methodologies that can lead to secure IoT application systems. This paper provides a framework to evolving IoT testbeds from the security services perspective, methodology and competency in IoT security which supports and enable multidisciplinary experimentation. Through a comprehensive literature survey of existing IoT testbeds, a set of core security design requirement for IoT security testbed is identified by examining vulnerabilities and attacks at every layer of architecture to get a deep understanding of the security assessment and best practices to conduct IoT security services.

Lightweight block ciphers have become a standard for security protections on IoT devices. Advanced technology is required to secure the data, thus encryption is the method that can provide information security. From previous studies, comparisons of lightweight algorithms in various literature focus on their performance and implementation. However, a lack of analysis has been done on the relationship between the algorithm components and their security strength. This information is crucial for developers in designing secure algorithms. In this paper, a comprehensive systematic literature review on 101 existing lightweight algorithms is presented. This review focuses on the security aspect of lightweight algorithms that cover the identification of secure design components based on substitution and permutation. Security analysis and the evolution of lightweight algorithms are also presented. This research includes the results and discussions to observe the selections of substitution and permutation functions to analyse their impact on the security strength. Recommendations from the developer's insight on methods and considerations for designing an algorithm are also presented. Findings from the research indicate that various techniques can be used to develop a secure algorithm. Most importantly, an algorithm must be provided with confusion and diffusion properties in the design to ensure sufficient security