Hamming Quasi-Cyclic (HQC) is a code-based key-encapsulation mechanism selected by NIST for post-quantum cryptography standardization, but it is challenging to deploy on resource-constrained devices due to its memory and computational costs. In this paper, we propose a novel software implementation of HQC, named MUTUALISM, which is deployable on resource-constrained devices. MUTUALISM builds on an efficient multiply-then-reduce method for sparse-dense polynomial multiplication that minimizes costly modular reduction operations. We further propose two variants of the multiplication algorithm that optimize memory footprint and computation throughput, respectively. We then present MUTUALISM as a unified and optimized implementation derived from fine-grained profiling of HQC. This implementation systematically integrates the aforementioned multiplication algorithms with additional optimizations throughout the HQC implementation pipeline, thereby reducing the memory footprint and improving end-to-end throughput. Our experiments on ARM Cortex-M4 show that MUTUALISM achieves a speedup of more than 57 times compared with PQClean while reducing the memory footprint by 80%. To the best of our knowledge, MUTUALISM is the first software-only HQC implementation deployable on resource-constrained devices with 64 KB of RAM across all security levels. This enables post-quantum key establishment on BLE-class IoT microcontrollers with only tens of kilobytes of SRAM, thereby bridging the gap between PQC standards and real-world wireless embedded deployments.

The recent machine learning requires huge machine resources and is often hard for users with limited resources. Although there are DPT, these are unsuitable for a situation where a trained model should be unrevealed from other users. In this paper, we first propose a new learning method, aggregated zero-knowledge deep learning (AZKDL), whereby even a user with a limited resource contributes to the learning process without revealing its model. Our main idea is to utilize aggregated zero-knowledge proofs where individual zero-knowledge proofs are aggregated into a single proof. Loosely speaking, users generate proofs for their training of parts of models and then aggregate both the models and the proofs to verify the entire models without revealing them. We also prove that AZKDL can detect malicious training. When we conduct experiments to evaluate AZKDL, we identify that even a client with the largest model parameters can finish the computation within a second. Furthermore, we propose the distributed proof-of-deep-learning (DPoDL) that rewards users who contribute to the learning process by applying AZKDL to a mining process of blockchains. DPoDL can detect malicious users by AZKDL.

Optical receivers for multichannel TV transmission in the VHF band are analyzed and tested from the viewpoints of linearity, sensitivity, and frequency response. Photodiodes and avalanche photodiodes are compared for use as a front-end detector. Optimization of the preamplifiers is studied in terms of both configurations and biasing conditions. Improvement of frequency characteristics, using a Percival coil, is also investigated. It is concluded that a receiver using a photodiode can attain as high a sensitivity as and a greater linearity (around 5 dB) than one using an avalanche photodiode.>

Analog transmission using laser diodes is quite attractive for transmitting multiplexed video signals, owing to the wide modulation bandwidth of laser diodes. Optimizations for transmitting color-TV signals (7 channel frequency division multiplexed) in the VHF band using buried heterostructure laser diodes are investigated. The major transmission objectives are a carrier to noise ratio of larger than 48 dB and intermodulation products of less than -55 dB. Design curves for minimizing distortion at the transmitter are demonstrated. A modulation index of 70 percent is shown to be capable of attaining the objective. Both the avalanche photodiode (APD) and the pinphotodiode (PD) are considered for use in the receiving amplifier. Minimum receiving power of -11 dBm obtained with the PD receiver is in good agreement with theoretical values. Deterioration of signal to noise ratio due to fiber guided transmissions is also reviewed in comparison with aerial transmissions.