RIS-Enabled Secret Key Generation for Secured Vehicular Communication in the Presence of Denial-of-Service Attacks.

Wireless communication has become an integral part of modern vehicles. However, securing the information exchanged between interconnected terminals poses a significant challenge. Effective security solutions should be computationally inexpensive, ultra-reliable, and capable of operating in any wireless propagation environment. Physical layer secret key generation has emerged as a promising technique, which leverages the inherent randomness of wireless-channel responses in amplitude and phase to generate high-entropy symmetric shared keys. The sensitivity of the channel-phase responses to the distance between network terminals makes this technique a viable solution for secure vehicular communication, given the dynamic behavior of these terminals. However, the practical implementation of this technique in vehicular communication is hindered by fluctuations in the communication link between line-of-sight (LoS) and non-line-of-sight (NLoS) conditions. This study introduces a key-generation approach that uses a reconfigurable intelligent surface (RIS) to secure message exchange in vehicular communication. The RIS improves the performance of key extraction in scenarios with low signal-to-noise ratios (SNRs) and NLoS conditions. Additionally, it enhances the network's security against denial-of-service (DoS) attacks. In this context, we propose an efficient RIS configuration optimization technique that reinforces the signals received from legitimate users and weakens the signals from potential adversaries. The effectiveness of the proposed scheme is evaluated through practical implementation using a 1-bit RIS with 64×64 elements and software-defined radios operating within the 5G frequency band. The results demonstrate improved key-extraction performance and increased resistance to DoS attacks. The hardware implementation of the proposed approach further validated its effectiveness in enhancing key-extraction performance in terms of the key generation and mismatch rates, while reducing the effect of the DoS attacks on the network.

Medically Graded Honey Supplementation Formula to Preterm Infants as a Prebiotic: A Randomized Controlled Trial.

OBJECTIVES: The aim of the study was to assess the effect of medically graded enteral honey supplementation on the intestinal microbiota, immune response, and somatic growth of preterm infants. METHODS: A prospective randomized controlled trial was conducted on preterm infants with gestational age ≤34 weeks and postnatal age >3 days. After reaching 1/2 goal enteral feeds, medically graded bee honey was added to milk at a dose of 5, 10, 15, and 0 g/day for 2 weeks in groups A, B, C, and D, respectively. Anthropometric measurements, CD4 and CD8 cytokines, stool cultures, and stool polymerase chain reaction assays for molecular detection of microbiomes were performed at 0, 7, and 14 days of intervention. Analysis of variance test was used to detect differences among the 4 groups. RESULTS: A total of 40 subjects were enrolled; 10 in each arm of the study. Compared with group D, all 3 intervention groups demonstrated significant increase in weight (P < 0.0001). Head circumference increased in groups B and C (P = 0.0056). There were no changes in CD4 or CD8 cytokines (P = 0.24 and P = 0.11, respectively). Enterobacter stool colonization decreased in groups A and B (P = 0.002), whereas Bifidobacterium bifidum colony counts increased in groups A, B, and C (P = 0.002) and lactobacilli colony counts increased in group B (P < 0.0001). Applying real-time polymerase chain reaction, B bifidum and lactobacilli increased in group C (P < 0.0001). CONCLUSIONS: Supplementation of milk formula with medically graded honey was associated with changes in physical growth and colonic microbiota of preterm infants. Further studies are needed to examine the sustainability of these effects and associated long-term outcomes.