Syndrome-Trellis Codes (STC), as the de facto state-of-the-art steganography framework, has drawn huge attention recently. However, the original STC merely developed with the general form of cover and message, and almost all the subsequent improvements for STC focused on the cover selection and design of the distortion cost function. How to select the optimal submatrix by the features for the given cover and message is an important issue and requires to be solved urgently. In this work, we propose to divide both the cover and message into segments and embed each message segment into its optimally matched cover segment. We name the proposed method as Segment-STC steganography. Specifically, by investigating the features of the submatrix used in STC, we first select the optimal submatrix, which could effectively reduce the number of distorted elements during the embedding. Then, the given cover and message will be split into a series of segments. Each message segment is adaptively matched with an optimal submatrix. We conduct the experiments on both the benchmark BOSS dataset and our collected on-line songs dataset. The experimental results show that, compared with the original STC, our method could effectively reduce the distortion and improve the undetectability of the stego.

Hexanal detection is essential for real-time monitoring of oil oxidation stability and evaluating health impact. Nevertheless, accurately monitoring hexanal levels in the presence of other volatile organic compounds (VOCs) remains a significant challenge. In this article, we present an In ₂ O ₃ /SnO ₂ composite-based electrochemical gas sensor that offers excellent selectivity for hexanal over other tested VOCs, such as styrene, acetone, and n-hexane, and featured a remarkably low detection limit of approximately 50 parts per billion (ppb). Additionally, a gas sensing device that integrated the aforementioned electrochemical hexanal sensor with blockchain technology was developed to facilitate remote monitoring of hexanal variations. In particular, shuffling technology and digital signatures were utilized to bolster the security of data transmission and access. It turns out that the developed sensing device demonstrated impressive performance in both sensing accuracy and data security, highlighting its potential as a promising solution for remote hexanal monitoring.