Hybrid Homomorphic Encryption (HHE) scheme integrates two types of Fully Homomorphic Encryption (FHE), arithmetic FHE and logic FHE to enhance the performance and scalability of privacy-preserving computations. However, the performance of HHE mainly depends on the efficiency of the Number Theoretic Transform (NTT). Accordingly, this paper introduces Hermes, an FPGA-based NTT accelerator for HHE. We have designed a cross-scheme-friendly NTT architecture that supports NTT of varying lengths through the reuse of NTT units. Experimental results demonstrate that our proposed architecture achieves high hardware utilization and increases throughput by 1.3× compared to existing state-of-the-art approaches across various NTT lengths.

This paper presents FastNN, a novel accelerator architecture for efficient K-Nearest Neighbors (KNN) search in point clouds. FastNN leverages a locality-sensitive E2LSH partitioning method and a precomparator module to significantly reduce the candidate search space and minimize the number of Euclidean distance calculations. Compared to octree-based partitioning methods, our approach reduces candidate points by 58.57% to 86.17% and achieves a $10.04 \times$ acceleration in processing throughput relative to the BitNN comparator subsystem. The proposed design effectively enhances search throughput, resource utilization, and precision, highlighting its potential for accelerating KNN search on FPGA platforms.

Abstract The emergence of digital media has changed the way people live and learn. In the context of the new era, digital media is gradually integrating into people’s life and learning. Digital media contains massive images, and fine-grained image recognition for digital media has become an important topic. The challenge of fine-grained image recognition is that the difference between different categories is small, and the difference between the same categories is sometimes large. This work designs a fine-grained image recognition based on feature enhancement (FIRFE). This extracts as much information as possible from fine-grained images under weak supervision to improve the recognition accuracy. When the existing methods extract image features, the feature extraction other than the most significant local feature is not enough. This deals with local features alone and ignores the relationship between features. First, this paper designs a feature enhancement and suppression module to process image features. Secondly, this paper designs pyramid residual convolution. This uses different scale convolution kernels to capture different levels of features in the scene. Thirdly, this paper uses the softpool method to rationally allocate the information weight in the pooling process. Fourth, this paper uses feature focus module to mine more features. This focuses on obtaining similar information in multiple local features as discriminant features to further improve the recognition. Fifthly, this paper carried out systematic experiments on the designed method. The proposed method achieves 94.3%/95.7% accuracy, 92.9%/94.1% recall, and 91.4%/92.2% F1 score on different datasets. This verified the superiority of this method for fine-grained image recognition of digital media.