Secure Digital Semantic Communications: Fundamentals, Challenges, and Opportunities

TL;DR

This work surveys security and privacy in digital semantic communication (SemCom), distinguishing it from analog SemCom by its finite-alphabet, packet-based transmission and explicit modulation. It catalogs a threat landscape that includes semantic leakage, manipulation, and knowledge-base/model vulnerabilities, then details unique digital-specific attacks on probabilistic and deterministic modulation as well as packet-/protocol-level exploits. The paper reviews defense strategies across bit/symbol leakage, modulation-specific attacks, and protocol threats, and outlines open problems and research directions, such as security-centric evaluation metrics and cryptography-modulation co-design, to enable practical, secure deployment of digital SemCom. By integrating security considerations into the modulation and protocol layers, this work lays a foundation for trustworthy digital SemCom in future wireless networks with edge intelligence and immersive applications.

Abstract

Semantic communication (SemCom) has emerged as a promising paradigm for future wireless networks by prioritizing task-relevant meaning over raw data delivery, thereby reducing communication overhead and improving efficiency. However, shifting from bit-accurate transmission to task-oriented delivery introduces new security and privacy risks. These include semantic leakage, semantic manipulation, knowledge base vulnerabilities, model-related attacks, and threats to authenticity and availability. Most existing secure SemCom studies focus on analog SemCom, where semantic features are mapped to continuous channel inputs. In contrast, digital SemCom transmits semantic information through discrete bits or symbols within practical transceiver pipelines, offering stronger compatibility with realworld systems while exposing a distinct and underexplored attack surface. In particular, digital SemCom typically represents semantic information over a finite alphabet through explicit digital modulation, following two main routes: probabilistic modulation and deterministic modulation. These discrete mechanisms and practical transmission procedures introduce additional vulnerabilities affecting bit- or symbol-level semantic information, the modulation stage, and packet-based delivery and protocol operations. Motivated by these challenges and the lack of a systematic analysis of secure digital SemCom, this paper reviews SemCom fundamentals, clarifies the architectural differences between analog and digital SemCom and their security implications, organizes the threat landscape for digital SemCom, and discusses potential defenses. Finally, we outline open research directions toward secure and deployable digital SemCom systems.

Figures (5)

• Figure 1: The end-to-end architectures of both analog and digital SemCom implementations: (a) analog SemCom framework; (b) digital SemCom framework. Architecturally, analog and digital SemCom mainly differ in whether the system explicitly defines a modulation-demodulation interface, as in standard digital transceivers, to transmit semantic information over a finite alphabet of discrete symbols or an equivalent bit stream.
• Figure 2: The detailed architecture of a digital SemCom system with explicit probabilistic or deterministic modulation and packet-based delivery. The JSC encoder/decoder denotes the joint source and channel coding/decoding module.
• Figure 3: An overview of the security and privacy threats against digital SemCom. The red dashed lines link threats to the corresponding stages where they arise. For probabilistic modulation, demodulation is often integrated with the JSC decoder, whereas for deterministic modulation, demodulation and the JSC decoder are typically implemented as separate modules. For clarity and a unified presentation, we depict demodulation and the JSC decoder as two distinct blocks to highlight the threats targeting each stage. This overview includes threats shared by both analog and digital SemCom as well as those unique to digital SemCom. In this paper, we primarily focus on threats specific to digital SemCom and their corresponding defenses.
• Figure 4: A summary table of possible defense strategies against security and privacy threats in digital SemCom, where Bob denotes the legitimate receiver and Eve denotes the eavesdropper.
• Figure 5: An overview of open problems and future research directions for secure and deployable digital SemCom.