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Computer Science Cryptography and Security

cs.CR Watch Cryptography and Security

Tuesday 19 May

Cryptography and Security

Awakening the Hydra: Stabilizing Multi-Concept Backdoor Injection in Text-to-Image Diffusion Models

Kai Wang, Jiale Zhang, Chengcheng Zhu et al. (+2 more)

Text-to-image diffusion models are increasingly developed through open-source reuse and repeated downstream fine-tuning, where reused checkpoints are difficult to verify and thus more susceptible to hidden backdoor behaviors. In such ecosystems, a single pretrained model may be sequentially adapted and redistributed by multiple independent parties, allowing multiple concept-specific trigger-target associations to accumulate in the same model. When these associations coexist, semantic conflicts can be amplified in the shared representation space, leading to cross-concept entanglement and degraded generation quality. Notably, instead of strengthening the attack, such accumulation can destabilize previously injected behaviors and reduce attack reliability. In this work, we systematically investigate backdoor attacks under this interference-prone setting and propose Hydra, a unified framework for robust and controlled multi-concept backdoor injection under cumulative and decentralized reuse. Our core insight is that stable backdoor injection under large-scale multi-concept settings requires explicitly constraining trigger semantics while coordinating cross-task interactions during optimization. Specifically, Hydra performs evolutionary trigger search in the text encoder space to identify triggers that are semantically aligned with their target concepts while remaining stable across other injected concepts. It further combines multi-task fine-tuning with trigger-clean regularization to improve training stability under dense multi-concept injection. Extensive experiments across multiple diffusion backbones under rigorous multi-concept settings show that Hydra maintains effective backdoor activation while preserving clean generation fidelity and image quality. For instance, across 8 attackers and 500 concept pairs, Hydra maintains ~95% ASR and strong clean generation.
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All authors Kai Wang, Jiale Zhang, Chengcheng Zhu, Chuang Ma, Songze Li

Cryptography and Security

SCARA: A Semantics-Constrained Autonomous Remediation Agent for Opaque Industrial Software Vulnerabilities

Bowei Ning, Xuejun Zong, Lian Lian et al. (+4 more)

Critical-infrastructure operators are increasingly expected to assess and remediate vulnerabilities in deployed industrial software. However, much of this software exists as opaque industrial software (OIS), including stripped firmware, proprietary protocol handlers, and compiled control logic without source code, symbols, build environments, or hardware interfaces. While binary analysis can identify vulnerability candidates, existing automated repair systems largely rely on source code, compilable artifacts, sanitizer feedback, or instrumentable builds, leaving a gap between binary-level discovery and validated remediation. This paper presents SCARA, a Semantics-Constrained Autonomous Remediation Agent for OIS. SCARA operates under a source-unavailable defender model and connects upstream binary vulnerability candidates to conditionally validated remedies through a four-stage pipeline. Operational-state-aware verification (OSVA) filters infeasible candidates using a nine-component industrial state model; remediation synthesis (RSA) selects the strongest available remedy across protocol mitigation, binary hardening, and SSCKG-constrained source patches; and correctness validation (CVA) provides conditional correctness evidence via behavioral-coverage preservation, independent replay, and typed rejection feedback. On OIS-RemedBench, a 15-case benchmark spanning firmware, protocol handlers, and ICS/PLC artifacts, SCARA achieves observed 100% precision with no false positives, refutes 20.0% of cases as operationally infeasible, and reaches 88.9% remediation success after targeted reruns. To our knowledge, SCARA is the first end-to-end framework that connects binary vulnerability candidates to conditionally validated remediation for opaque industrial software.
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All authors Bowei Ning, Xuejun Zong, Lian Lian, Kan He, Guogang Wang, Yifei Sun, Jinyang Liu

Cryptography and Security

Inferring Sensitive Attributes from Knowledge Graph Embeddings: Attack and Defense Strategies

Yasmine Hayder

Knowledge Graphs (KGs) are a powerful representation of linked data, offering flexibility, semantic richness, and support for knowledge enrichment and reasoning. They help data owners organize and exploit heterogeneous data to provide insightful services (e.g., recommendations), yet real-world KGs are often incomplete, hiding true facts or missing valuable insights. Knowledge graph embedding techniques are commonly used to infer valuable missing information. However, reasoning over KGs can inadvertently expose sensitive user information, even when such data is not explicitly stored. In this work, we investigate the privacy risks associated with KGE-based reasoning, focusing on attribute inference attacks where adversaries attempt to deduce sensitive user attributes from seemingly non-sensitive outputs. We propose and evaluate a framework that mitigates these privacy risks by applying post processing sanitization techniques to KGE outputs. Preliminary results demonstrate the effectiveness of these attacks on the outputs of KGE models, and explore the trade-off between recommendation quality and privacy protection when applying randomization based approaches, highlighting the need to experiment with more advanced techniques in future work to address this issue.
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Cryptography and Security

Exposing Functional Fusion: A New Class of Strategic Backdoor in Dynamic Prompt Architectures

Zeyao Liu, Zhendong Zhao, Xiaojun Chen et al. (+3 more)

Existing ViT backdoor attacks based on backbone-overwriting full-tuning are computationally expensive and inflict performance degradation. This has forced adversaries towards the Visual Parameter-Efficient Fine-Tuning (PEFT) paradigm, dominated by adapter-based (e.g., LoRA) and prompt-based (e.g., VPT) approaches. While adapter security has seen initial study, the risks of the burgeoning prompt-based ecosystem remain critically unexplored. We fill this critical gap, exposing how the evolution of VPT towards dynamic and context-aware architectures can facilitate a far more dangerous and emergent threat. This vulnerability arises even though these dynamic modules unlock superior benign performance. We propose VIPER, an attack framework built on a lightweight, dynamic Visual Prompt Generator (VPG) that demonstrates this vulnerability. Critically, this dynamic architecture enables Functional Fusion: an emergent phenomenon where malicious logic and benign task utility are tightly fused into the same sparse, high-magnitude parameter core. This fusion creates a formidable “hostage" dilemma, as pruning the attack necessarily destroys the benign performance. Comprehensive evaluations show VIPER effectively addresses the attacker's trilemma: VIPER not only achieves state-of-the-art performance on clean data, but also maintains near-100% ASR even under 90% VPG-module pruning (where LoRA attacks collapse), while adding only an imperceptible 0.06ms (1.16%) of inference latency. VIPER's results, driven by Functional Fusion, expose a new, paradigm-level risk in dynamic prompt architectures.
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All authors Zeyao Liu, Zhendong Zhao, Xiaojun Chen, Xin Zhao, Yuexin Xuan, Xiaoshuang Ji

Cryptography and Security

XAI FL-IDS: A Federated Learning and SHAP-Based Explainable Framework for Distributed Intrusion Detection Systems

Mohammad Hossein Gholamrezazadeh and AhmadReza Montazerolghaem

An Intrusion Detection System (IDS) is vital in cybersecurity, detecting unauthorized activity across networks. With attacks on network layers increasing, stronger IDSs are needed. Yet most IDSs rely on centralized detection, forcing IoT nodes to ship data to a server, adding overhead and offering no privacy guarantees. Moreover, conventional models focus solely on flagging attacks, without explaining how individual features influence those decisions. This research aims to address these dual limitations by first proposing a solution for privacy preservation and then adding explainability to the new system. We introduce an innovative framework called XAI FL-IDS, which integrates Federated Learning (FL) with Explainable AI (XAI). The XAI FL-IDS system eliminates concerns over data transfer because each node trains its data locally and only sends the necessary update parameters to the server. Additionally, all detections, both at the local node and central server levels, are scrutinized using SHapley Additive exPlanations (SHAP), providing detailed insight into the decision-making process. This system consists of a central server and 10 clients and utilizes the Edge-IIoTset dataset, which is distributed among all clients with careful attention paid to class balancing. On each client, the XGBoost model is executed on local data. The proposed method demonstrates robust efficiency and strong performance in intrusion detection, achieving an accuracy of over 99% and, at times, reaching 100%. By incorporating FL, the confidentiality of the network information on every local node is guaranteed.
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Cryptography and Security · Cross-listed from cs.NI

Fifty Shades of Darknet

Siddique Abubakr Muntaka, Faiza Hussein and Jacques Bou Abdo

The Invisible Internet Project (I2P) is a peer-to-peer anonymous overlay network whose architecture includes a structurally distinct sublayer not characterized in existing security literature. We term this sublayer the Exclusive Network: nodes here host operational services and draw on I2P's routing resources, but publish no RouterInfo record to the network's distributed database (NetDB). In a controlled three-node testbed, we demonstrate that an Exclusive Network node survives sequential floodfill queries from a pool of routers with zero NetDB hits, while its hosted service remains continuously accessible to authorized peers. This property is exploitable by documented I2P-based malware, for example, I2PRAT (RATatouille), for persistent command-and-control operations against national assets or corporate networks. The structure is analogous to nation-state Operational Relay Box (ORB) infrastructure. The existence of this sublayer, together with the inability of top-down empirical mapping to characterize it, motivates a move toward formal analytical methods to understand the emergence and behavior of covert networks within I2P.
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Cryptography and Security

High-Rate Public-Key Pseudorandom Codes for Edit Errors

Shengtang Huang, Xin Li, Songtao Mao et al. (+1 more)

Pseudorandom codes (PRCs), introduced by Christ and Gunn (CRYPTO '2024), are error-correcting codes whose codewords are computationally indistinguishable from uniformly random strings, while still being decodable by someone holding the key. They provide a natural primitive for robust and undetectable watermarking, particularly in applications to AI-generated content. Although recent works have obtained strong results for substitution errors, the edit-error setting remains much less understood, especially in the high-rate regime and over small alphabets. We study public-key pseudorandom codes against edit errors. First, we give a new reduction showing that binary zero-bit PRCs robust against a constant fraction of substitution errors can be transformed into binary zero-bit PRCs robust against edit errors. Consequently, under any assumption that yields zero-bit Hamming-robust PRCs, one also obtains zero-bit PRCs for edit channels, albeit only for the weaker class of sublinear polynomial edit channels, namely channels with edit error rate $1/n^{\gamma}$ for any constant $\gamma>0$. In the high-rate regime, we construct public-key PRCs with rate arbitrarily close to $1$ over sufficiently large constant alphabets, and with rate arbitrarily close to $1/2$ over the binary alphabet. Moreover, if we allow the alphabet size to be $\mathrm{poly}(\lambda)$, where $\lambda$ is the security parameter, then our public-key PRCs can attain the Singleton bound for insertion-deletion channels. Taken together, these results yield the first high-rate public-key binary PRC constructions for edit channels, under the same assumption that yields zero-bit Hamming-robust PRCs.
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All authors Shengtang Huang, Xin Li, Songtao Mao, Zhaienhe Zhou

Cryptography and Security

Locked Out at 8,000 Miles: Why UK-China Partnership Students Are Suffering

Benjamin Kenwright

University cybersecurity protocols have intensified dramatically in response to rising threats of data breaches, ransomware, and credential theft. While necessary, these measures have created a parallel crisis of accessibility - even for students physically on campus. This paper argues that domestic, on-campus students already face significant barriers: mandatory multi-factor authentication (MFA), device compliance rules, browser and operating system restrictions, and administrative remote-management permissions on personal phones and laptops. However, these difficulties are magnified to near-breaking point in the context of international partnerships, such as the increasingly common UK-China transnational education programmes. For a student in China accessing a UK university's virtual learning environment (VLE) from an 8-hour time difference, with no on-hand IT support during their active hours, the same security architecture becomes functionally disabling. Drawing on testimonies from public forums (Reddit's r/college, r/UniUK, r/Professors), higher education IT help boards, and student accounts from UK-China partnership programmes, this paper documents how over-engineering digital security disproportionately harms remote international learners. We show that while on-campus students can at least visit an IT desk or borrow a library terminal, their counterparts in partner institutions abroad face authentication failures, device lockouts, and unsupported browsers with no real-time remedy. The paper concludes that current university security models assume a co-located, 9-to-5, English-time-zone user - an assumption that fails both domestic students and, catastrophically, international partnership cohorts.
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Cryptography and Security

RoboJailBench: Benchmarking Adversarial Attacks and Defenses in Embodied Robotic Agents

Doguhuan Yeke, Yanming Zhou, Leo Y. Lin et al. (+3 more)

Recent advances in Vision-Language Models (VLMs) facilitate a new class of embodied AI systems, where these models are integrated into physical platforms, e.g. robots and autonomous vehicles, to interpret visual scenes and execute natural language commands in diverse environments. Previous research has introduced jailbreak attacks and defenses for embodied AI. Their evaluations, however, rely on ad-hoc datasets, limited metrics, and emphasize attack success while neglecting the trade-off between security and the ability to follow benign commands. Existing benchmarks and evaluation frameworks either target traditional chat-based models or focus on non-adversarial safety evaluation for embodied AI; neither captures the adversarial risks, inputs, consequences, and evaluation criteria necessary for jailbreak attacks in embodied AI systems. In this paper, we address this gap with RoboJailBench, which consists of three core components. We establish a security taxonomy derived from ISO standards, regulatory rules, and documented incidents. This effort yields 18 categories of security violation consequences for embodied AI. We introduce an intent contrast dataset pipeline that augments existing datasets with paired adversarial and benign goals to measure both security and utility. Lastly, we provide an evolving repository with standardized metrics and a unified process for assessing and integrating new attacks and defenses. With this benchmark, we construct a new taxonomy-balanced dataset and augment five existing datasets. We integrate four attacks and two defenses to evaluate their performance on leading embodied VLMs. This benchmark provides the first standardized evaluation framework for jailbreak attacks in embodied AI and supports future research. We release our code, datasets, and artifacts, and maintain a leaderboard at https://purseclab.github.io/benchmark-for-robotics-security.
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All authors Doguhuan Yeke, Yanming Zhou, Leo Y. Lin, Hongyu Cai, Antonio Bianchi, Z. Berkay Celik

Cryptography and Security

Exploring and Developing a Pre-Model Safeguard with Draft Models

Hongyu Cai, Arjun Arunasalam, Yiming Liang et al. (+2 more)

Large Language Model (LLM) alignment remains vulnerable to jailbreak attacks that elicit unsafe responses, motivating pre-model and post-model guards. Pre-model guards audit the safety of prompts before invoking target models. However, relying solely on the prompt often leads to high false-negative rates (i.e., jailbreak attacks go undetected). Post-model guards address this issue by auditing both the user prompt and the target model's response. However, they incur a high computational cost, including increased token usage and processing time, because they operate after target model inference. In this paper, we introduce a safeguard design that leverages the transferability of jailbreak attacks to enforce prompt safety before target model inference. We first conduct a systematic study of jailbreak transferability, particularly from LLMs to small language models (SLMs). Through these experiments, we identify key factors influencing transferability. Building on these insights, we observe that responses from smaller draft models reflect the safety implications of those from large target models; \ie given a jailbreak prompt constructed for an LLM, an SLM is likely to be triggered to generate an unaligned response. Based on this observation, our safeguard design leverages speculative inference with SLMs to generate a set of draft responses. It then feeds the original prompt and these drafts into existing guards to predict their safety. We demonstrate that this design reduces the false-negative rate of pre-model guards and offers a low \Efficiency alternative to post-model guards. \textcolor{red}Notice: This paper contains examples of harmful language.
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All authors Hongyu Cai, Arjun Arunasalam, Yiming Liang, Antonio Bianchi, Z. Berkay Celik

Cryptography and Security

MultiBallot: Verifiable and privacy-preserving E-Collecting in the Swiss setting

Florian Moser and Léo Louistisserand

As part of the political process, citizens may participate in signature collections to influence policy changes. In Switzerland, this even results in legally binding acts, similar to an election system. In this work, we first derive a realistic setting for e-collecting in Switzerland, based on the setting established for e-voting. Then, we propose a secure protocol in this setting, achieving both privacy and verifiability under realistic trust assumptions. Notably, participation privacy is guaranteed without assuming an anonymous channel, by considering the fact that at any given point in time, many collections are active in parallel.
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Cryptography and Security · Cross-listed from cs.LG

Backdooring Masked Diffusion Language Models

Daniel Yiming Cao, Chengzhong Wang, Sheng-Yen Chou et al. (+3 more)

Masked diffusion language models (MDLMs) are emerging as a compelling new paradigm for text generation, but their training-time security remains largely unexplored. Existing backdoor attacks on Gaussian diffusion models or autoregressive language models do not directly apply to MDLMs because MDLMs rely on discrete state corruption and iterative denoising rather than continuous noising or left-to-right prediction. In this work, we present the first systematic study of training-time backdoor attacks on MDLMs. We propose SHADOWMASK, a backdoor attack that modifies the MDLM forward corruption process by replacing the standard all-mask terminal distribution with a trigger-mask mixture prior. This creates a dedicated denoising pathway from trigger-corrupted states to attacker-specified targets while preserving clean denoising behavior. We further provide a principled mathematical formulation by defining the backdoored forward process, deriving the reverse-time posterior, and obtaining the continuous-time training objective. Evaluations on DiT-based MDLM and LLaDA-8B-Instruct across WikiText-103, OpenWebText, and Alpaca show that SHADOWMASK achieves near-100% attack success, substantially outperforms standard data poisoning, largely preserves clean utility, remains effective under full-model and parameter-efficient fine-tuning, and is robust against representative defenses.
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All authors Daniel Yiming Cao, Chengzhong Wang, Sheng-Yen Chou, Chengyu Huang, Pin-Yu Chen, Shengwei An

Cryptography and Security

Detecting and Mitigating Backdoor Attacks in OTA-FL Systems: A Two-Stage Robust Aggregation Scheme

Xiaoyan Ma, Seohyun Lee, Taejoon Kim et al. (+1 more)

Over-the-air federated learning (OTA-FL) improves communication efficiency by exploiting the superposition property of wireless channels, but this same property also creates a critical security vulnerability: the parameter server (PS) cannot access individual local updates, making it difficult to identify and exclude poisoned gradients. The challenge is further exacerbated under non-independent and identically distributed (Non-IID) training data, where benign gradient drift can closely resemble malicious updates. In this paper, we propose a two-stage robust aggregation framework for defending against backdoor attacks in OTA-FL. Under our scheme, each client is first assigned a modality-aware multi-indicator trust score, where the specific indicators are selected according to the data modality (e.g., waveform, text, image) and model architecture to capture the most discriminative footprint of backdoor updates. Based on this score, the PS then performs trust-based multiple access (TBMA) to separate clients into trusted, suspicious, and malicious categories. Suspicious clients are further examined through PS-side layer-wise inspection and a longitudinal reputation mechanism. Experimental results on several datasets demonstrate that the proposed methodology effectively suppresses stealthy backdoor attacks, including bounded-scaling attacks, Euclidean-constrained attacks, Cosine-constrained attacks, and Neurotoxin, while maintaining competitive main-task accuracy.
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All authors Xiaoyan Ma, Seohyun Lee, Taejoon Kim, Christopher G. Brinton

Cryptography and Security

Quantum Machine Learning for Cyber-Physical Anomaly Detection in Unmanned Aerial Vehicles: A Leakage-Free Evaluation with Proxy-Audited Feature Sets

Carlos A. Durán Paredes, Javier E. León Calderón, Nicolás Sánchez Perea et al. (+2 more)

Unmanned aerial vehicles (UAVs) are cyber-physical systems whose attack surface spans networked avionics and on-board sensor fusion: a compromised GPS or battery module can mimic a benign mission segment and evade naive anomaly detectors. We present a leakage-free evaluation of quantum machine learning for UAV anomaly detection on the multi-sensor TLM:UAV benchmark. Three contributions support the study. (i) A group-aware temporal protocol (B2) partitions the dataset into ten contiguous TimeUS blocks and evaluates over ten seeds, eliminating the inflation produced by random stratified splits that mix neighbouring samples. (ii) A three-mode feature audit (full/loose/strict) quantifies how much accuracy stems from instantaneous physical signals versus contextual proxies (cumulative energy, battery state, GPS trajectory). (iii) A hybrid XGBoost + Data Reuploading (DRU) classifier is benchmarked against five paired non-linear controls (raw, PCA, polynomial-2, random-RBF, and an untrained DRU map) under identical budgets. The standalone DRU does not consistently match the strongest classical baseline across seeds; however, the trained-DRU hybrid is the only model whose mean F1 macro shifts upward from full to strict (+0.05), a directional signal that the per-seed standard deviations prevent from being interpreted as a statistically established difference. The trained-DRU hybrid also records the lowest mean false-alarm rate under proxy-free evaluation, subject to the inter-seed variance reported. We frame this as an incremental, reproducible quantum-enhanced hybrid benefit, and provide an open Qiskit 2.x implementation as a benchmark for cybersecurity analytics in NISQ-era aerospace systems.
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All authors Carlos A. Durán Paredes, Javier E. León Calderón, Nicolás Sánchez Perea, Germán Darío Díaz, Camilo Segura Quintero

Cryptography and Security

Devilray: A Reconfigurable Adversarial Baseline for Revealing Blind Spots in Fake Base Station Detection

Taekkyung Oh, Duckwoo Kim, Hansung Bae et al. (+8 more)

Fake Base Station (FBS) detection has been a critical focus of cellular security research for over two decades. However, significant financial and regulatory barriers to accessing commercial FBS (C-FBS) devices have limited direct visibility into real-world operations, forcing detection systems to be designed and evaluated around self-built prototypes. In this paper, we present Devilray, a reconfigurable adversarial baseline to guide effective FBS detection by exploring the realistic adversarial space and identifying blind spots in detection systems – regions of realistic adversarial behavior excluded by prevailing threat models. To this end, we establish an empirical anchor through the first academic analysis of a C-FBS, define a fundamental four-phase pipeline and seven operational feature dimensions for adversarial behaviors, and extend them with operational variants derived from 3GPP standards analysis. Through combinatorial configurations of operations from commercial practices and specifications, Devilray enables the exploration of 2,592 FBS instances, spanning diverse operational possibilities. Using Devilray, we evaluate seven currently accessible FBS detectors and uncover coverage gaps across all seven, revealing blind spots rooted in assumption-bound design and evaluation. Our work provides an empirically grounded adversarial baseline for evaluating FBS detectors and guiding future detection design, with Devilray and its configuration profiles released to vetted research groups.
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All authors Taekkyung Oh, Duckwoo Kim, Hansung Bae, Beomseok Oh, CheolJun Park, Tyler Tucker, Nathaniel Bennett, Sangwook Bae, Byeongdo Hong, Patrick Traynor, Yongdae Kim

Cryptography and Security

Token by Token, Compromised: Backdoor Vulnerabilities in Unified Autoregressive Models

Tobias Braun, Jonas Henry Grebe, Hossein Shakibania et al. (+2 more)

Unified autoregressive models (UAMs) are transformer models that generate text as well as image tokens within a single autoregressive pass. Shared parameters and a multimodal vocabulary simplify the training pipeline and facilitate flexible multimodal generation, yet might introduce new vulnerabilities. In particular, we are the first to show that this unified architecture enables multimodal backdoor attacks, where a trigger can propagate malicious effects across multiple output modalities. Specifically, we present the Token by Token Backdoor Attack (ToBAC), the first backdoor attack targeting UAMs, exploring both data-based and model-based poisoning strategies. We demonstrate that inconspicuous characters or even common words can be transformed into triggers that elicit harmful behavior in autoregressive image generation. ToBAC can jointly manipulate visual outputs and accompanying text, increasing the perceived authenticity of fabricated content. With model access, ToBAC enables attacks on the Liquid model in which a subtle word (e.g., "cool") induces modality-aligned brand promotion or ideological influence in 55% of generations. Without model access, ToBAC can be induced through data poisoning, achieving an average success rate of 63.1% against JanusPro. Our code is available at https://github.com/multimodal-ai-lab/ToBAC.
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All authors Tobias Braun, Jonas Henry Grebe, Hossein Shakibania, Anna Rohrbach, Marcus Rohrbach

Monday 18 May

Cryptography and Security

Subtle Injection for Ground-truth Inference of LLM Training Data

Abraham Itzhak Weinberg

As large language models (LLMs) are increasingly trained on scraped web corpora without authorisation, content owners require forensic methods to prove that their documents were included in a model's training set. We propose SIGIL (Subtle Injection for Ground-truth Inference of LLM training data), a framework that embeds imperceptible canary sequences into protected text and code such that any LLM trained on those documents exhibits statistically detectable behavioural signatures when probed with targeted queries. SIGIL defines five canary strategies – lexical-rare, lexical-phrase, syntactic, semantic, and code-pattern – and a Membership Inference Score (MIS) grounded in the Neyman-Pearson hypothesis testing framework with formal false-positive rate (FPR) control. Simulator parameters are calibrated against the empirical membership inference literature, yielding realistic heterogeneous results across $36{,}000$ trials: overall AUC $= 0.892$, rising from $0.831$ at $0.1\%$ injection to $0.947$ at $10\%$. Detection rates range from $33\%$ to $78\%$ across model-size and injection-rate conditions. Code Pattern canaries achieve the highest AUC ($0.903$, Cohen's $d = 1.84$); Syntactic Structure the lowest ($0.875$, $d = 1.63$). All four experimental factors – injection rate, model size, canary strategy, and mixture ratio – have significant independent effects on MIS ($p < 0.001$). SIGIL maintains AUC $> 0.86$ even under $100\%$ paraphrasing ($\text{AUC} = 0.864$), confirming robustness through semantic leakage that survives surface-level rewriting.
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Cryptography and Security

Escaping the Linearity Trap: Manifold Detours for Black-Box Adversarial Attacks on Singing Audio Deepfake Detection

Yifan Liao, Yule Liu, Zhen Sun et al. (+5 more)

Recent Singing Voice Synthesis (SVS) advances enable highly realistic but potentially malicious AI covers, making singing voice deepfake detection (SVDD) crucial. Self-Supervised Learning (SSL)-based detectors achieve state-of-the-art performance by fine-tuning speech SSL backbones to capture singing-specific spoof artifacts. Existing adversarial attacks often fail against SSL-SVDD, creating a false impression of inherent robustness. We reveal this stems from two challenges. First, at the objective level, attacks optimize cross-entropy on local surrogates, crossing surrogate-specific boundaries rather than suppressing shared spoof evidence. Second, at the method level, attacks follow the surrogate's dominant gradient direction. In SSL-SVDD, this aligns with fine-tuned artifact-sensitive directions, limiting transferability to unseen detectors - a geometric failure we term the Linearity Trap. To properly evaluate robustness, we propose MARS (Meta-Adversarial Regression of Semantics), a transfer-based black-box framework tailored to SSL-SVDD. Structurally, MARS shifts to hypothesis-evidence manipulation by constructing a natural semantic anchor from the pre-trained SSL space and an artifact anchor from the fine-tuned space. Algorithmically, MARS escapes the Linearity Trap via bi-level optimization: the inner stage induces tangential exploration, while the outer stage guides the audio toward the natural semantic manifold. Experiments on the CtrSVDD benchmark show MARS improves Attack Success Rate (ASR) in in-distribution transfer (13%), out-of-distribution transfer (10%), and cross-task evaluation (36%), highlighting the urgent need for robust SVDD systems.
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All authors Yifan Liao, Yule Liu, Zhen Sun, Zongmin Zhang, Yupeng He, Jiaheng Wei, Xinhu Zheng, Xinlei He

Cryptography and Security · Cross-listed from cs.LG

It Takes Two: Complementary Self-Distillation for Contextual Integrity in LLMs

Sangwoo Park, Woongyeong Yeo, Seanie Lee et al. (+6 more)

Contextual Integrity (CI) defines privacy not merely as keeping information hidden, but as governing information flows according to the norms of a given context. As large language models are increasingly deployed as personal agents handling sensitive workflows, adhering to CI becomes critical. However, even frontier models remain unreliable in making disclosure decisions, and existing mitigation strategies often degrade underlying task performance. To overcome this privacy-utility trade-off, we propose SELFCI, a complementary self-distillation framework that decouples information suppression from task resolution. SELFCI jointly optimizes two independent reverse KL divergences over distinct teacher distributions derived from feedback: one encourages preserving task-relevant information for utility, while the other enforces minimal and appropriate disclosure. This complementary formulation induces a Product-of-Experts (PoE) target, aligning the policy with the intersection of capability and privacy requirements. Empirical evaluations demonstrate that SELFCI, without relying on costly external supervision, consistently outperforms competitive baselines such as online reinforcement learning algorithms (e.g., GRPO). These trends further extend to out-of-domain settings involving agentic workflows and accumulated private context, suggesting that SELFCI provides a practical path toward CI alignment.
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All authors Sangwoo Park, Woongyeong Yeo, Seanie Lee, Yumin Choi, Hyomin Lee, Kangsan Kim, Jinheon Baek, Seong Joon Oh, Sung Ju Hwang

Cryptography and Security · Cross-listed from cs.AI

Hallucination as Exploit: Evidence-Carrying Multimodal Agents

Guijia Zhang, Hao Zheng and Harry Yang

Multimodal agents increasingly choose tool calls from screenshots, documents, and webpages, where a false perceptual claim can turn hallucination from an answer-quality error into an authorization failure. We formalize this failure mode as hallucination-to-action conversion: an unsupported claim supplies the precondition for a privileged action. We propose evidence-carrying multimodal agents (ECA), which treat free-form model text as inadmissible evidence, decompose each tool call into action-critical predicates, obtain typed certificates from constrained DOM/OCR/AX verifiers, and use a deterministic gate to authorize only the privileges those certificates support. Rather than hiding perception error, ECA converts opaque model belief into auditable residuals at the verifier, schema, and implementation levels. Verifier red-teaming across 17 canonical attack categories shows that four targeted hardening steps are each necessary; after hardening, canonical gate bypass is 0/1,700 (Wilson 95% upper bound 0.22%). With content-derived certificates, ECA observes zero unsafe executions on 200 end-to-end tasks (Wilson 95% upper bound 2.67%) and 120 browser tasks (upper bound 4.3%). A HACR audit on 500 stratified task keys shows that unsupported action-critical claims reach unsafe execution for naive agents (100.0%) and prompt-only defenses (49.6%), but not for ECA. Oracle-certificate replay over 7,488 GPT-5.4 traces isolates gate correctness, while neural judge baselines still admit most unsafe actions under the same threat model. The resulting principle is simple: model language may propose tool use, but certified predicates must authorize it.
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Cryptography and Security

On the Geometric Limits of Transformer Defenses against Obfuscation Attacks: Latent Embedding Collapse & Performance Robustness Gap

Becky Mashaido and Tapadhir Das

Prompt injection attacks pose significant risks to language model safety, yet existing defenses are typically evaluated using classification performance. We show that high detection performance does not imply representational robustness. Specifically, multi-operator obfuscated prompts (combining homoglyphs, zero-width characters, and punctuation or emoji noise) can partially collapse onto the embedding manifold of clean prompts, a phenomenon we term latent embedding collapse. Results indicate that across multiple BERT family encoders with varying depth and capacity, detectors achieve near-perfect classification performance, yet the minimal clean-obfuscated margin delta = 1.02, indicating near-overlap of obfuscated and clean embeddings. Obfuscated embeddings further exhibit elevated intra-class variance (3.33 +/- 6.23), indicating severe latent-space instability despite high performance. These results reveal a substantial perf ormance-robustness gap, demonstrating that standard evaluation metrics fail to capture latent embedding collapse and underlying geometric fragility. Our findings show that increasing model capacity does not eliminate latent embedding collapse, motivating geometry-aware robustness analysis as a necessary complement to performance-based evaluation for prompt-injection defenses.
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Cryptography and Security · Cross-listed from cs.CL

Agent Meltdowns: The Road to Hell Is Paved with Helpful Agents

Rishi Jha, Harold Triedman, Arkaprabha Bhattacharya et al. (+1 more)

Agents operating with computer and Web use inevitably encounter errors: inaccessible webpages, missing files, local and remote misconfigurations, etc. These errors do not thwart agents based on state-of-the-art models. They helpfully continue to look for ways to complete their tasks. We introduce, characterize, and measure a new type of agent failure we call accidental meltdown: unsafe or harmful behavior in response to a benign environmental error, in the absence of any adversarial inputs. Because meltdowns are not captured by the existing reliability or safety benchmarks, we develop a taxonomy of meltdown behaviors. We then implement an agent-agnostic infrastructure for injecting simulated local and remote errors into the rollout environment and use it to systematically evaluate agent systems powered by GPT, Grok, and Gemini. Our evaluation demonstrates that meltdowns (e.g., conducting unauthorized reconnaissance or subverting access control) of varying severity and success occur in 64.7% of agent rollouts that encounter simulated errors, spanning all combinations of agent system, backing model, and error type. In over half of these meltdowns, unsafe behaviors are not reported to the user. Comparing behaviors of the same agents with and without errors, we find that exploration in response to errors is correlated with unsafe and harmful behavior.
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All authors Rishi Jha, Harold Triedman, Arkaprabha Bhattacharya, Vitaly Shmatikov

Cryptography and Security

Be Kind, Rewrite: Benign Projections via Rewriting Defend Against LLM Data Poisoning Attacks

John T. Halloran and Noopur S. Bhatt

Large language models (LLMs) are highly susceptible to backdoor attacks (BAs), wherein training samples are poisoned using trigger-based harmful content. Furthermore, existing defenses have proven ineffective when extensively tested across BA patterns. To better combat BAs, we explore the use of LLM rewriting as a proactive defense against data poisoning. First, we theoretically show that when LLM rewriting utilizes open-book benign samples–termed open-book benign rewriting (OBBR)–the probability of a rewritten output being benign is strictly greater than that of closed-book rewriting. Thus, OBBR neutralizes harmful content by projecting training samples to the space of benign prompts. We then show that, in contrast to previous defenses, OBBR effectively mitigates a large number of existing BAs: across five known BAs and four widely used LLMs, OBBR increases safety performance by an average 51% compared to state-of-the-art BA defenses and 25.7% compared to closed-book rewriting methods. Finally, we show that OBBR is computationally efficient relative to other BA defenses, does not degrade model performance on natural language tasks after fine-tuning, and is capable of defending against non-trigger based data poisoning attacks.
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Cryptography and Security

Structural Analysis of Cryptographic Sequences using Stringology-Based Fingerprinting

Victor Kebande

Cryptographic primitives such as stream ciphers,Pseudorandom Number Generators (PRNGs), and block cipher modes produce sequences that are designed to be statistically indistinguishable from random data. As a result, the traditional evaluation techniques therefore rely primarily on statistical randomness tests to assess the quality of generated sequences. While these tests verify global statistical properties, they do not address whether structural characteristics of sequences can reveal information about the underlying generator. In this paper, we introduce a stringology-based fingerprinting, (SBF) framework for the structural analysis of cryptographic sequences. The proposed SBF framework interprets cryptographic outputs as symbolic strings and applies pattern-based feature extraction to capture structural statistics such as substring frequency distributions, recurrence patterns, and entropy characteristics. These structural features are aggregated into fingerprint vectors that characterize sequence generators. The experimental evaluation is conducted using datasets composed of Cipher-Generated Sequences (CGS) and Uniformly Random Sequences (URS). The results demonstrate that stringology-based pattern analysis can reveal measurable structural signatures across different sequence sources. Although these signals do not imply practical cryptographic weaknesses, they provide an additional analytical perspective for evaluating the structural behavior of cryptographic generators.
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Cryptography and Security

Agent Security is a Systems Problem

Mihai Christodorescu, Earlence Fernandes, Ashish Hooda et al. (+11 more)

We take the position that agent security must be approached as a systems problem: the AI model powering the agent must be treated as an untrusted component, and security invariants must be enforced at the system level. Through this lens, efforts to increase model robustness (the dominant viewpoint in the community) are insufficient on their own. Instead, we must complement existing efforts with techniques from the systems security domain. Based on our experience as cybersecurity researchers in operating systems, networks, formal methods, and adversarial machine learning, we articulate a set of core principles, grounded in decades of systems security research, that provide a foundation for designing agentic systems with predictable guarantees. As evidence, we analyze eleven representative real-world attacks on agents and discuss how systems principles, if realized, could have prevented these attacks. We also identify the research challenges that stand in the way of implementing these principles in agents.
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All authors Mihai Christodorescu, Earlence Fernandes, Ashish Hooda, Somesh Jha, Johann Rehberger, Kamalika Chaudhuri, Xiaohan Fu, Khawaja Shams, Guy Amir, Jihye Choi, Sarthak Choudhary, Nils Palumbo, Andrey Labunets, Nishit V. Pandya

Cryptography and Security · Cross-listed from cs.GT

Concave is the New Linear: The Impossibility of Anti-Plutocratic DAO Governance

Austin Bennett, Preston Vander Vos, Duc V. Le et al. (+1 more)

Decentralized Autonomous Organizations (DAOs) run protocol governance by letting token holders vote on proposals. The dominant rule, voting power proportional to wallet balance, concentrates control among a small number of large holders, fueling the token-control governance attacks that have already compromised real protocols. To counter this concentration, the community has turned to anti-plutocratic voting mechanisms such as Quadratic Voting (QV), which assign sublinear voting power per token with the goal of dampening the influence of large holders. We prove that no voting rule that derives power solely from wallet balance can succeed on a permissionless blockchain. Through a costed model of on-chain voting that captures realistic blockchain frictions – including per-wallet splitting and voting costs, fixed setup costs, and minimum-balance requirements – we show that whenever a wallet of any size yields nonzero voting power, a Sybil attacker who splits tokens across many wallets achieves total voting power that grows at least linearly in their token holdings. For concave rules actually proposed to dampen governance power – those that are positive, increasing, and finite – we show that the optimal strategy yields power that is asymptotically linear in token holdings, regardless of the cost scheme. Instantiating the model on real DAOs reveals attack costs orders of magnitude below the value at stake. Replaying the ten most recent finalized proposals of five major DAOs (ENS, Compound, Uniswap, Arbitrum, and ZKsync) under linear, quadratic, logarithmic, and power-($\beta = 0.25$) voting, we measure Sybil amplification factors between $1,172\times$ and $4,039\times$ under Quadratic Voting, and exceeding $229,000\times$ under steeper power rules.
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All authors Austin Bennett, Preston Vander Vos, Duc V. Le, Mira Belenkiy

Cryptography and Security

Surviving the Unseen: Predictive Defense for Novel Multi-Turn Multimodal Attacks

Doohee You

The expansion of Multimodal Large Language Models (MLLMs) and their integration into autonomous agentic workflows has introduced a non-stationary attack surface. Empirical observations indicate that adversaries employ progressive, cross-modal perturbations that evade turn-specific guardrails by distributing malicious intent across longitudinal conversational trajectories. Static defense mechanisms, constrained by the Markov property, evaluate inputs in isolation and fail to detect cumulative structural poisoning. To handle this limitation, this paper formulates safety verification as a dynamic survival prediction and trajectory dynamics problem. The Triple-tier Anomaly Defense (TRIAD) framework is proposed as a predictive model that maps multimodal and multi-turn conversational flow as a continuous trajectory. The framework integrates structural anomaly detection to monitor covariance shifts, a Ledoit-Wolf regularized Mahalanobis distance to monitor covariance shifts in high-dimensional spaces, and topological trajectory acceleration to differentiate benign creative exploration from continuous malicious drift. These kinematic and geometric features are integrated into a time-varying Cox Proportional Hazards model via a Bayesian Hidden Markov Model (HMM) feedback loop. Theoretical analysis demonstrates that the TRIAD framework provides a mathematically bounded expected time-to-failure under adversarial perturbations, ensuring that malicious acceleration diverges positively. This framework provides a computationally efficient, interpretable, and predictive safeguard for real-time agentic AI systems, establishing a rigorous foundation for continuous safety alignment without relying on empirical retraining.
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Cryptography and Security

OEP: Poisoning Self-Evolving LLM Agents via Locally Correct but Non-Transferable Experiences

Kaixiang Wang, Jiong Lou, Zhaojiacheng Zhou et al. (+1 more)

Memory-augmented large language model (LLM) agents use iterative reflection and self-evolution to solve complex tasks, but these mechanisms introduce security risks. Existing agentic memory attacks require privileged access or explicit malicious content, making them detectable by advanced safety filters. This leaves a subtler attack surface underexplored: whether adversaries can induce agent to generate experiences that appear locally correct and semantically plausible yet induce harmful generalization during reflection. We find that reflective agents are vulnerable to such clean experiences, especially when paired with severe but plausible hypothetical consequences. Based on this observation, we introduce Obsessive Experience Poisoning (OEP), a low-privilege black-box attack requiring no direct control over the system prompt or memory database. OEP constructs adversarial clean edge-cases that combine locally correct solutions, non-transferable methods, and severe consequences, biasing reflection toward risk-averse rule formation. During memory consolidation, agents may over-trust self-generated reflections and distill localized experiences into high-priority but over-generalized rules, causing downstream failures. Evaluations across three domains show that OEP achieves ASR above 50% with GPT-4o agents, and outperforms existing attacks under LLM auditing defense.
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All authors Kaixiang Wang, Jiong Lou, Zhaojiacheng Zhou, Jie Li

Cryptography and Security · Cross-listed from quant-ph

A Risk-Aware Framework for Covert Quantum Communication under Stochastic Channel Uncertainty

Abbas Arghavani, Shahid Raza, Maryam Amiri et al. (+1 more)

Covert quantum communication (CQC) seeks to hide not only message content but also the existence of communication. Existing CQC models usually assume deterministic or worst-case channel conditions, which are difficult to justify in realistic free-space optical and quantum links affected by turbulence, fluctuating background radiance, and stochastic detector noise. We propose a stochastic risk-aware optimization framework for CQC under uncertain physical-layer conditions. By modeling transmissivity and background noise as random variables, we express covertness and reliability guarantees through chance constraints with explicit outage budgets $\epsilon_{\text{cov}}$ and $\epsilon_{\text{rel}}$. This recasts CQC design as a risk-calibrated resource-allocation problem balancing throughput, covertness, reliability, and communication privacy. We derive quantile-based reformulations of the outage constraints, characterize feasible operating regions under stochastic uncertainty, and introduce a complementary risk-adjusted utility formulation to expose throughput-risk trade-offs. The analysis reveals that modest relaxations in acceptable covertness-outage risk can yield large throughput gains, while aggressive optimization may break covertness outside sparse-transmission regimes. Monte Carlo results under log-normal fading and stochastic thermal noise show that the framework expands feasible operating regions, improves covert throughput by more than an order of magnitude, and identifies degradation boundaries beyond which covert operation becomes unreliable. These results move CQC closer to realistic secure quantum networking for free-space, satellite, and low-probability-of-detection applications.
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All authors Abbas Arghavani, Shahid Raza, Maryam Amiri, Alessandro Papadopoulos

Cryptography and Security

MoCo-EA: Exploiting Adversarial Mode Connectivity for Efficient Evolutionary Attacks

Hyo Seo Kim, Gang Luo, Can Chen et al. (+3 more)

Evolutionary algorithms for adversarial attacks leverage population-based search to discover perturbations without gradient information, but suffer from inefficient crossover operations that destroy adversarial properties through discrete interpolation. We introduce Mode Connectivity Evolutionary Attack (MoCo-EA), which replaces traditional crossover with a novel Bézier crossover operator that optimizes perturbations along a continuous Bézier curve between parent perturbations. Our key insight is that adversarial examples lie on connected manifolds where intermediate points maintain and often enhance attack effectiveness. We demonstrate three findings: (1) Successful adversarial perturbations exhibit mode connectivity; (2) Intermediate points along optimized paths achieve higher transferability than endpoints; (3) Bézier crossover dramatically outperforms discrete genetic operations while reducing convergence time and query requirements. By exploiting the geometric structure of adversarial space through path optimization, MoCo-EA provides an efficient and reliable method. Our work challenges the traditional view of adversarial examples as isolated points and opens new directions for both attack generation and defense research.
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All authors Hyo Seo Kim, Gang Luo, Can Chen, Binghui Wang, Yue Duan, Ren Wang