Secure Semantic Communication over Wiretap Channels: Rate-Distortion-Equivocation Tradeoff

2025-09-15

AI Summary

This paper investigates information-theoretic modeling of semantic-aware secure communication over wiretap channels, focusing on lossy joint source-channel coding (JSCC) for memoryless semantic sources. Two encoder settings are formulated: (i) only the observable source is available, and (ii) both the semantic and observable sources are directly accessible. A novel rate-distortion–entropy-decoupling trade-off framework is proposed, unifying semantic fidelity, observation fidelity, and their respective secrecy constraints for the first time. A new random superposition coding scheme is designed to enable independent entropy-decoupling analysis of semantic and observation components. Using information-theoretic techniques, single-letter converse and achievability bounds are derived. Specialized analyses and numerical validations are conducted for Gaussian/Bernoulli sources and Gaussian/binary wiretap channels. The results characterize tight rate-distortion–entropy-decoupling regions, quantify security-fidelity gains enabled by semantic access, and generalize classical source and channel coding theory.

Technology Category

• Machine Learning: Information Theory
• Cognitive Modeling & Cognitive Systems: Neural Spike Coding
• Search and Optimization: Mixed Discrete/Continuous Search

Application Category

• Security and Privacy: Large-scale security measurements
• Semantics and Knowledge: Methods to enhance, augment, integrate or synergize semantic models such as knowledge graphs and LLMs
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems

Abstract

This paper investigates an information-theoretic model of secure semantic-aware communication. For this purpose, we consider the lossy joint source-channel coding (JSCC) of a memoryless semantic source transmitted over a memoryless wiretap channel. The source consists of two correlated parts that represent semantic and observed aspects of the information. Our model assumes separate fidelity and secrecy constraints on each source component and, in addition, encompasses two cases for the source output, in order to evaluate the performance gains if the encoder has an extended access to the source. Specifically, in Case 1, the encoder has direct access only to the samples from a single (observed) source component, while in Case 2 it has additional direct access to the samples of the underlaying semantic information. We derive single-letter converse and achievability bounds on the rate-distortion-equivocation region. The converse bound explicitly contains rate-distortion functions, making it easy to evaluate, especially for some common distributions. The proposed achievability coding scheme involves novel stochastic superposition coding with two private parts to enable analysis of the equivocation for each source component, separately. Our results generalise some of the previously established source and source-channel coding problems. The general results are further specialised to Gaussian and Bernoulli sources transmitted over Gaussian and binary wiretap channels, respectively. The numerical evaluations illustrate the derived bounds for these distributions.

Problem

• Secure semantic communication over wiretap channels with fidelity and secrecy constraints
• Rate-distortion-equivocation tradeoff for correlated semantic and observed sources
• Evaluating performance gains with extended encoder access to source components

Innovation

• Stochastic superposition coding with two private parts
• Separate fidelity and secrecy constraints on source components
• Single-letter converse and achievability bounds derivation