Three-Dimensional Discrete Heterogeneous-Neuron HNN and Hardware Image Encryption
摘要
Nonlinear activation functions are central to the rich dynamics of Hopfield neural networks (HNNs), yet the impact of heterogeneous nonlinearities remains underexplored. This paper proposes a three-dimensional discrete heterogeneous Hopfield neural network (3D-DHNN) with sine, hyperbolic tangent and sigmoid-type activation functions. We show that this simple, sparsely coupled architecture generates coexisting multifold hyperchaotic attractors with high entropy and strong randomness, and we validate its behavior through FPGA implementation. Building on this chaotic source, we design a password-driven image encryption scheme that combines CML-Hilbert scrambling with a strictly invertible bidirectional plaintext-feedback diffusion, where all parameters are derived from a joint key/plaintext key-derivation function. Experiments and hardware tests on a Zynq-7020 device demonstrate near-ideal statistical security, negligible pixel correlation, perfect decryption, and a throughput of 76.8 Mbps, confirming the practicality of the proposed system for real-time secure image transmission.