Cryptography and Security · Cross-listed from cs.CL
Breaking Refusal in the First Half: A Mechanistic Study of the Prefill Jailbreak
Alex Kwon
Aligned
language models refuse harmful requests, but a one-line prefill ("Sure, here is") strips the refusal. We ask where and how it fails. The harm representation stays intact: on the
prompts the attack flips to compliance, a linear probe reads harm as high as on the refused ones (0.91-0.98), while behavioral refusal drops to chance. This holds across four models and three families (1.5-3.8B, and at 14B). Refusal is therefore a shallow, response-site computation. We localize it to an early window: a dose-matched position control shows the first half of the response suffices to break refusal, while the second half is nearly inert. Three causal probes converge on that window. Restoring the harm direction there partially re-engages refusal. Injecting the model's own refuse-state reverses the jailbreak (74%, held-out). And knocking out the early response's
attention to the prefill, but not an equal
attention mass elsewhere, selectively collapses the harmful continuation. A base-model control identifies the mechanism: the same knockout collapses the continuation prefill-specifically even in a non-safety-tuned base model (64% to 25% harmful content vs a matched control's 64%, replicated at 7B). So the prefill's grip is generic autoregressive conditioning, not safety-specific suppression, and "refusal restoration" is a model-dependent fallback. The dominant mechanism is passive. A small safety-specific attractor remains on top (logit-trace concentration 0.24 vs 0.03), whose active-vs-passive character we size but do not fully separate. No single direction or component is a clean handle either: the decision is decodable but distributed, and refusal tracks harm rather than scary surface. The consequence is structural: a monitor reading the untouched
prompt-side representation is immune by construction, but only to response-site attacks. The mechanism is diffuse; the failure surface is local.
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Cryptography and Security · Cross-listed from cs.CV
Delving into the Temporal Challenges of Unified Video Protection Against Image-to-Video and Fine-Tuning-based Customization
Yuxin Huang, Ziming Hong, Mingming Gong et al. (+3 more)
Recent
diffusion-based
video generation models have enabled high-quality personalized
video customization through both tuning-based pipelines, which fine-tune a
video diffusion model, and reference-based pipelines such as image-to-
video generation. However, these capabilities raise serious concerns about personal
privacy, identity ownership and intellectual property protection. Existing anti-customization works focus on protecting images, while protection for
videos against both reference- and tuning-based customization remains largely underexplored. Protecting
videos in this setting raises three challenges: (i) Image-level perturbations, optimized frame by frame, cannot survive temporal compression by 3D
video VAE. (ii) A
video-level perturbation optimized on a single
video is vulnerable to temporal editing and fails to protect unseen
videos. (iii) Temporally inconsistent perturbations are not robust to temporal attacks. To address these challenges, we propose Temporally Consistent Universal
Adversarial Perturbations (TC-UAP), the first protection method against both reference- and tuning-based
video customization. TC-UAP optimizes an identity-level multi-frame UAP over sliding windows from multiple
videos, accounting for local temporal dependencies induced by temporal compression in
video VAE and enabling a single perturbation to protect unseen
videos of varying lengths. Moreover, we introduce intrinsic temporal modeling and an extrinsic surrogate temporal-attack loss, which make the perturbation temporally consistent and robust to unseen temporal attacks. Empirically, quantitative and qualitative results show that TC-UAP achieves the strongest identity protection compared with existing methods under both reference- and tuning-based
video customization, and remains robust under multiple unseen temporal attacks.
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All authors Yuxin Huang, Ziming Hong, Mingming Gong, Wanyu Wang, Jing Zhang, Tongliang Liu
Cryptography and Security
Privacy Preserving Recommender Systems Balancing Personalization with Privacy
Ranjeet K Jha and Venkata Suresh Gummadilli
Personalized recommendation systems are central to modern e-commerce and retail platforms, but they typically rely on centralized storage of detailed user interaction data, creating significant
privacy and regulatory challenges. With increasing requirements from regulations such as GDPR, CCPA, and CPRA, organizations must develop recommendation systems that preserve user
privacy without substantially degrading recommendation quality. This work presents and evaluates a
privacy-preserving recommendation framework that combines
federated learning, differential
privacy, cohort-level modeling, and
privacy-aware intelligent
agents. The framework keeps raw user data decentralized while introducing mathematically bounded noise to model updates. Experiments were conducted on synthetic retail
datasets that emulate customer clickstream and purchase behavior. Recommendation quality was evaluated using Click-Through Rate (CTR), Precision@K, Recall@K, and Normalized Discounted Cumulative Gain (NDCG@K) across multiple differential
privacy budgets. We evaluate
matrix factorization, neural collaborative filtering, and GRU4Rec under varying
privacy constraints and analyze the trade-off between
privacy and utility. An interactive Streamlit dashboard was developed to visualize recommendation performance, ranking stability,
privacy-utility trade-offs, and
fairness metrics. Results show that the proposed framework maintains competitive recommendation quality at moderate
privacy budgets (approximately $\epsilon \approx 5$), demonstrating that strong
privacy guarantees can be achieved with limited impact on recommendation effectiveness. This work provides a practical framework for deploying
privacy-preserving recommendation systems that balance personalization, regulatory compliance, and business objectives, offering a scalable approach for next-generation AI-driven retail platforms.
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Cryptography and Security
Proof in a Bottle: Long-Lived Verifiable Secret Sharing via Pre-Quantum Commitment and Immutable Ledger Binding
Markus Jakobsson and Keir Finlow-Bates
Traditional secret sharing techniques such as Verifiable Secret sharing (VSS) are vulnerable to
quantum attacks by a Cryptographically Relevant
Quantum Computer (CRQC) running Shor's
algorithm. We observe that the binding a VSS needs is required only at the moment of dealing, and this binding can be made before any CRQC exists. We propose Proof in a Bottle (PiB), which decouples verifiability from long-term binding: standard Pedersen commitments provide zero-knowledge, publicly checkable consistency during a pre-
quantum window, while a salted, index-bound hash of the share set, anchored to an immutable public ledger, preserves the binding established in that window into the post-
quantum era. The guarantee is explicitly a commit-now, reveal-later one: it protects today's honest dealings against tomorrow's
quantum adversary.
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Cryptography and Security · Cross-listed from cs.AI
AI-Native Insurance for Agentic AI: Pricing, Underwriting, and End-to-End Automation
Quanyan Zhu
Agentic AI introduces new insurance challenges because autonomous AI systems can make decisions, invoke tools, modify external environments, and interact with third-party services. This paper develops an AI-native mathematical framework for underwriting, pricing, and contract design for agentic AI deployments. A deployment is represented by a risk state that captures autonomy level, operational authority, permission exposure, governance maturity, and dependency concentration. The framework maps the risk state to event probabilities, loss severities, governance costs, premiums, deductibles, coverage allocation, and policy covenants, and formulates an optimization problem for insurance contract design under participation, profitability, and incentive compatibility constraints. The paper establishes structural properties of insurability, including characterization of an insurability region, monotone deterioration of feasibility with increasing exposure, and governance certification thresholds. Insurance is further interpreted as both an operational cost and a regulatory mechanism for AI deployment. A healthcare case study illustrates contract optimization, sensitivity analysis, and automated claims processing for agentic AI systems.
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Cryptography and Security
Why Not Fix It Once and for All? An Empirical Study of Multiple Patches for Vulnerability Fixes in Open-Source Software
Weiliang Qi, Youpeng Li and Xinda Wang
Security patches for open-source software constitute a foundational resource for vulnerability remediation research and practice. However, analyzing and applying multiple patches remains challenging, especially when trying to determine at what point in a patch sequence a vulnerability is fully remediated. This paper presents a systematic analysis of multi-patch vulnerability fixes, focusing on their root causes, characteristics, and methods for verifying remediation status throughout the fixing process. Through a manual examination of 1,646 multi-patch fix records, we develop a taxonomy with three primary categories and six subcategories based on their causes. We then compare the distinctive characteristics of multi-patch fixes with those of single-patch fixes and analyze feature variations across categories. In addition, we assess representative vulnerability detection methods for validating complete remediation during multi-patch fixing. Our findings provide new insights into multi-patch fixes and lay a foundation for future research in this field.
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Cryptography and Security
BARS: Benign-Anchored Ranking and Selection for False Alarm Reduction in Network Intrusion Detection
Abu Fuad Ahmad and Istiaque Ahmed
False alarms remain a major barrier to deploying network intrusion detection systems (NIDS). In high-volume environments, even a sub-1% false positive rate can generate tens of thousands of daily alerts. Filter-based feature selection is attractive because it operates upstream of the classifier and adds no inference-time cost. However, classical filters use class-symmetric criteria that ignore the asymmetry of intrusion detection, where benign traffic defines the baseline and attacks are deviations from it. A recent class-asymmetric filter, Classwise Mean Deviation (CMD), addresses this issue but anchors its score to a global mean that shifts toward attack distributions under class imbalance, weakening the deviations it aims to capture. We propose Benign-Anchored Ranking and Selection (BARS), a two-stage filter that replaces CMD's global anchor with the benign-class mean and applies an order-preserving decorrelation step. We evaluate BARS on CICIDS2017, CICDDoS2019, and UNSW-NB15 using feature budgets k = {5, 10, 20, 30, 40}. On attack-majority
datasets, where global-anchor bias is strongest, BARS reduces false positive rate relative to CMD by 15.4% on UNSW-NB15 at k = 20 and by 21% to 23% on CICDDoS2019 at small feature budgets while preserving true positive rate and macro-F1. On benign-majority data, BARS and CMD converge, consistent with the theoretical limit where global- and benign-anchored scores coincide. BARS reduces false alarms by up to 32% while maintaining similar detection rates, with larger gains under stronger imbalance. Ablation results show that the two stages provide complementary benefits and select a consistent set of robust features. BARS retains linear-time scoring and a low
memory footprint, making it suitable for resource-constrained deployments.
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Cryptography and Security
Composable Trust for Language Models: A proven boundary and a measured defense
Yakov Pyotr Shkolnikov
In a
language model, instructions and data share one
token stream, so nothing inside the model's generation can keep untrusted text from steering it. We develop a trust model that places the authority to act outside the model, in code: a source's standing, not its content, decides which operation runs and whether it acts. A lower-trust source may inform an answer but not override a higher one. An unmodified model runs inside a deterministic pipeline that ranks inputs by source integrity, and a fixed non-model monitor provably chooses the operation and any outside action from trusted inputs alone. We can measure but not prove the pipeline's resistance to injection; we
prompt-tune it and report the rate. On a one-shot held-out set with an unmodified Gemma~4 26B model, passivation and a wrapper (the cascade) raise the genuine-leak defended rate from $27\%$ to $94\%$ at roughly a $4\%$ clean-quality cost ($Q_{\mathrm{rel}}{=}0.96$). Under adaptive red-teaming the proved boundary holds unconditionally, and the measured defense stays at $87\%$. The cascade also attributes a lower-trust source's fact rather than dropping it, raising attribution from $0\%$ to $92\%$, and follows the higher-trust source on a conflict.
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Cryptography and Security
AI in Cyberpsychology: A systematic literature review of Cybersecurity enhancement by using AI for analyzing psychology of Victims, Attackers, and Defenders
Georg Thamer Francis, Malek Malkawi, Sevim Eyüpoğlu et al. (+2 more)
Cybersecurity is the practice of protecting systems, networks, and data from digital attacks. Cyberpsychology (CPSY) is defined as the use of psychology to enhance cybersecurity applications. Since the early 2010s, the
evolution of Artificial Intelligence (AI) has increasingly integrated with CPSY, leveraging advanced data analysis to decode the distinct personality traits and behavioral patterns of victims, attackers, and defenders. In this systematic literature review (SLR), we carefully analyze 34 collected research studies of AI usage in cyberpsychology (AI-CPSY) using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) methodology. The review presents a comprehensive taxonomy of the cyber-security applications, the AI methodologies used, and the psychological concepts employed across the studies . We sort the research studies into four cybersecurity applications: Anomaly Detection (AD), Vulnerability Risk Prediction (VRP), Security Awareness Training (SAT), and Authentication/Identity Verification (AIV). Within each application area, studies are further sorted according to the AI method used including machine learning (ML), deep learning (DL), natural
language processing (NLP), and reinforcement learning (RL). Furthermore, the review identifies the most commonly utilized psychological concepts, quantify the
datasets used in the field, and present their current implementation and deployment status. At last, it detect research gaps, present open challenges, and deduce the trending and most effective and emerging methodologies used across the AI-CPSY landscape.
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All authors Georg Thamer Francis, Malek Malkawi, Sevim Eyüpoğlu, Reda Alhajj, Selim Akyokuş
Cryptography and Security
Designing a GDPR-Compliant Security Architecture for Remote Elderly Care Systems: A Privacy-by-Design Approach
Md. Rahid Parvez and Mikael Soini
IoMT-based remote elderly care systems generate continuous streams of sensitive health data, yet existing security architectures have not simultaneously addressed three interdependent challenges: GDPR-compliant edge-layer pseudonymisation, elderly-specific zero-interaction usability as a binding architectural constraint, and integrated STRIDE-based threat validation within a single unified design. This paper presents the Secure Edge Gateway (SEG) framework - a software-simulation-validated integrated IoMT security architecture for elderly care designed to resolve all three dimensions of this tripartite gap simultaneously. An ESP32-WROOM-32 residential gateway enforces MAC address whitelisting, HMAC-SHA256 cryptographic pseudonymisation before any network transmission, AES-128-CBC payload encryption, and TLS 1.3 transport security, in compliance with GDPR Articles 25 and 32. The framework is validated through software-based simulation, full STRIDE threat modelling across all six categories, attack tree analysis, GDPR compliance mapping across nine regulatory obligations, and a Data Protection Impact Assessment (DPIA) under Article 35. Published
benchmarks confirm MQTT consumes 6-8% less energy than HTTP in comparable IoT deployments, and edge processing achieves sub-50 ms response latency versus 200-700 ms for cloud-only systems. The results demonstrate that GDPR compliance and operational efficiency are complementary - not competing - objectives in resource-constrained IoMT deployments for elderly care.
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Cryptography and Security
WaterMoE: Expert-Routing-based Watermarking for High Fidelity and Efficiency
Z Sun, Q Jiang, S Sheng et al. (+1 more)
Large
language models (LLMs) have achieved remarkable success but raise growing concerns about content provenance and misuse, motivating the need for reliable watermarking techniques. However, these techniques have rarely been adopted in practice mainly for two reasons: i) severely degraded model performance, and ii) additional inference overhead. To confirm the problem, we construct a comprehensive
benchmark spanning different generation tasks to systematically evaluate 9 representative watermarking methods. We found almost all existing methods are designed for text fluency, but not for restricted and complicated tasks, and their overhead prevents them from deployment in latency-critical systems. To address i) and ii), we propose an LLM watermarking scheme WaterMoE for the growingly popular Mixture-of-Experts (MoE) LLMs. WaterMoE embeds watermarking signals through controlled perturbation into the expert selection at each router, which accumulates to
token selection shift at the final output. In contrast to watermarking as a post-processing
token-sampling approach, WaterMoE embeds watermark within the inference loop incurring negligible quality degradation and computational overhead. Extensive experiments demonstrate that our method achieves a fidelity performance close to the unwatermarked and consistently outperforms state-of-the-art watermarking methods on the
benchmark, with up to $4\times$ speedup, incurring merely 1% additional inference latency compared to native generation. The results demonstrate the capability of WaterMoE to be deployed in real-world tasks.
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All authors Z Sun, Q Jiang, S Sheng, L Xiang
Cryptography and Security
Efficient and Privacy Aware Edge Cloud Collaborative Inference for Large Language Models
Cheng Li, Jiexiong Liu, Yixuan Chen et al. (+1 more)
On-device LLM inference faces a trilemma of response latency, limited hardware resources and user
privacy. Full cloud inference delivers strong computing power but exposes user
prompts and dialogue data, while standalone on-device inference is unfeasible for most consumer and embedded edge devices. This paper presents a
privacy-centric edge-cloud collaborative LLM inference framework built on endpoint-authenticated KV cache. Local endpoints handle input preprocessing,
embedding computation, adaptive feature optimization, KV cache authentication, speculative decoding and low-dimensional model head calculation, while the cloud conducts authenticated decoder inference, KV cache management,
token verification and high-dimensional vocabulary projection. Endpoints fuse partial outputs, apply
language-adaptive masking and sample target
tokens. All transmitted data and truncated logits are quantized and AES-GCM encrypted for
privacy, with core lightweight modules, draft parameters and cache access policies kept local to avoid leakage. The framework supports heterogeneous devices including CPU-only, GPU-equipped and embedded devices via optimized streaming, batching and quantized ONNX deployment. Evaluations demonstrate that the framework reduces per-
token latency by up to 46.1% and downlink payloads by up to 67.4% over baseline split inference, retaining comparable performance to full cloud inference.
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All authors Cheng Li, Jiexiong Liu, Yixuan Chen, Yi Li
Cryptography and Security
Watermark Forensics for Generative Models: An Information-Theoretic Perspective
Xiaoyu Li, Zheng Gao, Xiaoyan Feng et al. (+3 more)
A watermark in a generative model's output is usually asked only whether a text is machine-made. The same mark can do more: attribute it to the user who produced it, extract a hidden payload, or localize the part that survives editing. These form a forensic ladder, and we ask what each rung costs in the sample length $n$. One object organizes the answers. Let $S$ be the secret the mark carries (a user's identity or payload), and let the information profile $\nu(t)=I(S;X_t\mid X_{<t})$ record how much the $t$-th
token reveals about $S$ given the earlier ones. Its total mass pays for attribution and extraction; how that mass is spread pays for localization; and detection alone is paid for not by information but by presence, the distance from the marked to the unmarked distribution. The literature's two quality models, a mark subtle on every
token and one that stamps a few
tokens loudly, are two incomparable ways of capping this profile. Our main
theorem settles the ladder's
entropy column. For statistically distortion-free schemes, attributing a text to one of $N$ users costs $\Theta(\log N/h)$
tokens over every stationary-ergodic source of
entropy rate $h$, sharp to a $(1+o(1))$ factor: to our knowledge the first tight
entropy-rate law for multi-user attribution (via exact
alignment). The natural collision-counting analysis overcharges without bound; only a decoder thresholding each candidate by its own realized surprisal attains the rate while almost never implicating an innocent user. A matching converse makes the law two-sided, and extraction of an $\ell$-bit payload costs $\Theta(\ell/h)$. Two gaps are real, not modeling artifacts: a $\Theta(\log N)$-
token window in which a text is provably machine-made yet unattributable, and a footprint-resolution uncertainty principle. Experiments on GPT-2, Pythia-410M, and Qwen2.5 recover the predicted constants.
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All authors Xiaoyu Li, Zheng Gao, Xiaoyan Feng, Jiaojiao Jiang, Yulei Sui, Jiankun Hu
Cryptography and Security
Silent Alarm: A J-Space Protocol for Comparing Danger Recognition Across Models and Quantization Levels
Roman Prosvirnin, Victor Minchenkov, Alexey Soldatov et al. (+2 more)
Jailbreak-robustness research typically evaluates safety through generated responses using an LLM-as-judge approach. Such evaluations, however, are sensitive to the
benchmark's grading procedure and capture only observed behavior on a given set of attacks, without directly revealing the hidden fragility of the underlying safety mechanisms. This work proposes JADR (Jacobian Assessment of Danger Recognition), a protocol that measures a model's internal representation through Jacobian space (J-space, a recently proposed workspace of verbalizable concepts) before the first response
token is generated. For every
prompt and layer we record the top-k J-space
tokens; these are grouped into six behavioral scenario axes and compared between a danger sample based on StrongREJECT and a safe control drawn from XSTest and OKTest. The method does not call on an external judge model: the computation runs entirely locally, on the activations of the model under evaluation, which lets us compare both different models against each other and modifications of a single model - quantization and fine-tuning in particular - on the same terms. The final comparison rests on the proposed SafetyAUC metric, complemented with bootstrap confidence intervals. The protocol is applied to six models (Qwen3-1.7B, Qwen3-4B, Qwen3-8B, Qwen3-Uncensored-4B, Qwen3-SafeRL-4B, Gemma 2 9B) across three weight-representation regimes - BF16, INT8, and INT4 - and checked against an independent behavioral evaluation with the StrongREJECT grader. The metric separates models with a strong versus a weak internal safety mechanism with statistical significance and captures substantively different effects across quantization regimes.
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All authors Roman Prosvirnin, Victor Minchenkov, Alexey Soldatov, Vladimir Bashun, Anton Sergeev
Cryptography and Security
A Scalable Cloud-Orchestrated and Service-Oriented Multi-Domain QKD Network with PQC Integration
Konstantinos Krilakis, Antonia Tsili, Aikaterini Mandilara et al. (+1 more)
Quantum key distribution (QKD) offers unconditional security but existing QKD networks remain difficult to scale across heterogeneous infrastructures and administrative domains due to vendor-specific interfaces, trusted-node constraints, and limited interoperability. This work presents a flexible multi-domain and multi-site
quantum-secure network architecture integrating vendor-agnostic QKD, SDN orchestration, and cloud-managed trust services. Communication is based on Zero Trust Network Access protocols featuring multi-level authentication mechanisms building upon post-
quantum cryptography (PQC) signature and key encapsulation
algorithms. The system is deployed on a real-world testbed with domains incorporating QKD nodes from 3 vendors, as well as domains without QKD infrastructure elements. Experimental results show that PQC and SDN overhead remain relatively low even on constrained devices, with the main bottleneck being QKD key
retrieval and vendor-specific key streaming limitations. The proposed framework extends
quantum-safe key transport beyond native QKD boundaries while preserving flexibility, interoperability, and compatibility with existing infrastructures.
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All authors Konstantinos Krilakis, Antonia Tsili, Aikaterini Mandilara, Dimitris Syvridis
Cryptography and Security
Stability Buys Time: A Re-Keying Game for Encrypted Multi-Agent Control
Sai Sandeep Damera and John S. Baras
Encrypted control lets a cloud coordinate a fleet of
agents on fully homomorphically encrypted state, keeping their positions and commands private. The approximate scheme for real-valued control, CKKS, returns decryptions that carry the encryption noise, a key-recovery leak; the loop must decrypt to actuate, so the leak is unavoidable. Yet the security of approximate FHE is studied statically, encrypted control assumes an honest-but-curious cloud, and persistent-threat games never reach inside the cryptosystem. We model the loop's security under an advanced persistent threat as a two-phase game, passive reconnaissance then active manipulation, separated by a measured residual detector that sees only the manipulation. The passive phase reduces to the known flooding tradeoff; the active defense is re-keying, not bootstrapping, since only re-keying resets accumulated leakage. The active phase is a detection-evasion timing game: overt manipulation is caught, so the rational adversary stays stealthy, and at its Stackelberg
equilibrium the defender re-keys on the laziest cadence that denies it, set by the control-theoretic fragility of the graph
topology. The marginally-stable graph must re-key far more often than the well-connected one. A three-way tension among FHE precision, control accuracy, and re-key cadence sets where this game lives, between a securability floor and a static-suffices ceiling. The efficient secure point is that window, where re-keying is the price of precision efficiency. More broadly, security for an approximate cryptosystem in a feedback loop is a dynamic game whose defender's move is the scheme's own refresh, applying beyond control to any system that must repeatedly decrypt to act.
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Cryptography and Security
Bulkhead: Automated Semantic Detection and Remediation of Container Escape Vulnerabilities
Qiyuan Fan, Zhi Li, Junjie Li et al. (+3 more)
Container filesystem isolation depends on safely resolving container-controlled paths during privileged host-container interactions. As third-party plugins and
agent sandboxes introduce more interactions, unsafe path resolution can redirect host operations across isolation boundaries, expanding the attack surface for path traversal vulnerabilities. These logic flaws are difficult to mitigate: kernel defenses require intrusive redesign, static rules miss cross-boundary semantics, and manual auditing cannot scale. Large
Language Model (LLM) based methods can detect syntax flaws through stable code patterns and identify logic flaws in domains such as smart contracts by comparing equivalent implementations. Container components, however, provide neither form of regularity: their heterogeneous interfaces operate under trust boundaries, filesystem views and interaction orders, making the security invariant difficult to find. We present Bulkhead, an automated framework for detection and remediation. Bulkhead summarizes historical CVEs into structured semantic patterns, correlates documentation with entry and effect side code evidence, and recovers source-to-sink execution contexts. Grounded patterns guide LLM
reasoning, while isolated Proof-of-Concept (PoC) execution validates findings. For remediation, Bulkhead generates repository-specific patches, checks that they build, and iteratively verifies path safety and functionality using pattern derived model checking templates and counterexamples before runtime validation. Across container repositories, Bulkhead discovered 20 zero-day vulnerabilities, accounting for 43% of the total number discovered over the past decade. Among them, 3 have been assigned CVEs and the verified patch suggestions have been submitted to the upstream.
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All authors Qiyuan Fan, Zhi Li, Junjie Li, XiaoFeng Wang, Bin Yuan, Deqing Zou
Cryptography and Security
Auditable and Transparent Fully Authenticated Disk Encryption via USB Storage Interposition
Enrique Soriano-Salvador and Gorka Guardiola Múzquiz
Full Disk Encryption (FDE) has become increasingly important in the last decades due to the evident confidentiality concerns. In most systems, encryption is provided by an operating system driver, through which the user can transparently access the encrypted disk after supplying the required keys (or the credentials from which those keys are derived). In this work, we explore an alternative approach: the use of an intermediate USB device placed between the host system and the external hard disk, where the encrypted data are stored. Although there are existing devices that follow this inline approach (such as RAID controllers and USB enclosures with built-in encryption), we explore the use of a general-purpose single-board computer running Linux with USB On-The-Go support (e.g. a Raspberry Pi), to provide FADE (Fully Authenticated Disk Encryption). Our system, named CC (Cryptographic Companion), performs the cryptographic operations (encryption/decryption and authentication), providing a standard USB mass-storage interface to the host (which is entirely unaware of the presence of encryption) while relying on the external USB hard disk to store the corresponding encrypted blocks. Our design provides several key advantages: flexibility, low cost, transparency, the use of generic hardware and free and open-source software, adaptability to emerging cryptographic schemes, and mitigations against malicious disk firmware. This paper presents the design and implementation of the CC and an experimental evaluation of our current research prototype, which indicates that it is sufficiently efficient for most common use cases.
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Cryptography and Security
PVDetector: Detecting Prompt Injection Attacks on Purpose-Specific LLM Agents through Policy-Violation Concept Analysis
Junhui Wang, Hangtao Zhang, Zhirun Zheng et al. (+5 more)
Large
language models (LLMs) are increasingly deployed as purpose-specific
agents to handle domain-specific tasks such as customer service and code generation. These
agents are expected to comply with not only generic safety guardrails but also purpose-specific restrictions tailored to their designated roles. Such additional restrictions enlarge the attack surface, particularly to
prompt injection (PI) attacks. To defend against such attacks, existing detection methods primarily rely on analyzing input-output patterns, yet yield limited effectiveness. To address this limitation, we turn to analyzing the hidden activation space and discover that LLMs inherently retain latent policy-violation (PV) concepts when prompted with requests beyond their designated purpose. Particularly, PV concepts capture the semantics of conflicts between user queries and predefined restrictions, implicitly reflecting LLMs' intrinsic awareness of recognizing policy violations. Building on this insight, we propose PVDetector, a training-free framework that detects PI attacks during LLM inference by measuring hidden-state
alignment with PV concepts, which are derived offline from the contrastive pairs of policy-violating and policy-compliant
prompts. Experiments across multiple LLMs and
datasets show that PVDetector achieves <1% false negative rate with minimal auxiliary overhead, consistently outperforming state-of-the-art methods. Our code is available at https://github.com/Claresigle/PVDetector .
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All authors Junhui Wang, Hangtao Zhang, Zhirun Zheng, Li Zeng, Jiejun Xiao, Xi Luo, Lihua Yin, Saiqin Long
Cryptography and Security · Cross-listed from cs.SD
Explainable-by-Design Audio Deepfake Detection via Wiener-Hopf Linear Prediction
Mattia Tamiazzo, Simone Milani, Massimo Iuliani et al. (+1 more)
The rapid advancement of synthetic
speech generation methods has made audio deepfake detection a critical challenge in multimedia forensics. While recent approaches achieve high detection accuracy, they typically rely on black-box architectures that offer limited interpretability and high computational complexity. In this paper, we propose an explainable-by-design audio deepfake detection framework based on Wiener-Hopf linear prediction, processed by a lightweight 2D Convolutional Neural Network (CNN). This design enables a direct and transparent connection between classification outcomes and the acoustic properties of the signal. Experimental results on
benchmark datasets demonstrate competitive detection performance while maintaining significantly lower computational complexity compared to state-of-the-art solutions. The interpretability analysis using Grad-CAM reveals that the classifier focuses on low-order predictor coefficients and on silence and transitional regions, suggesting that the Wiener-Hopf predictor captures reverberation characteristics and subtle statistical inconsistencies in synthetic
speech. Finally, robustness experiments show that fine-tuning effectively recovers detection performance under common post-processing degradations, including additive noise, MP3 compression, and telephone filtering.
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All authors Mattia Tamiazzo, Simone Milani, Massimo Iuliani, Marco Fontani
Cryptography and Security
How Agentic Is Agentic Commerce? A Population-Scale Measurement of x402 Adoption and Authenticity
Shengchen Ling, Yajin Zhou, Lei Wu et al. (+1 more)
AI
agents are said to be forming an economy in which they pay, on their own, for the data, APIs, and compute they consume. x402, which settles a stablecoin payment on-chain for each purchase, is the most widely deployed protocol for this, and its hundreds of millions of settlements are read as proof that the economy has arrived. We show the count cannot be read as adoption: it is the one metric an interested party can manufacture almost for free, since the facilitator sponsors the gas and nothing on-chain marks who controls a payment. We give the first population-scale measurement of x402 on Base, supplemented with a coarser Solana census. Identifying settlements from their on-chain event and resolving the true payer through the meta-transaction layer, we sort each by what its trace can prove via a payment graph. Over a 280-day window Base carries 136{,}708{,}672 settlements worth \$44{,}121{,}383.81, concentrated on every axis we measure (payer, recipient, and value Gini all above 0.98), yet 21.20\% are fictitious and 63.78\% internal settlement within a linked cluster. What is genuinely independent is bounded: it lies between the \$187{,}861.35 that demonstrably reaches a nameable service and the \$20{,}258{,}746.09 (45.92% of value) not provably manufactured. Finally, we resolve the count's manufacturable component, a coherent operator-driven economy,
star-shaped, machine-timed, and gas-subsidized. Settlement count measures manufacturability, not adoption.
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All authors Shengchen Ling, Yajin Zhou, Lei Wu, Cong Wang
Cryptography and Security · Cross-listed from cs.CV
Traceback Translators Against Forgetting in Continual Fake Speech Detection
Enrico Gottardis, Mattia Tamiazzo and Simone Milani
Fake
speech detectors are increasingly challenged by the development of new and more accurate generative models. To cope with this problem, continual learning techniques are nowadays widely considered feasible strategies for updating models to new
datasets, but they also lead to decreased performance on previously seen samples (catastrophic forgetting). In this work, we propose a forgetting-resilient solution based on the adoption of domain translators within a frozen detector, which remaps the new feature spaces into the original ones by means of a traceback translator network. Experimental results show that this strategy enables the achievement of high detection rates with respect to traditional retraining, while minimizing the computational effort and preserving the detection accuracy on previous data.
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Cryptography and Security
VanillaBench: The Hidden Accuracy Cost of Adversarial Robustness
Niklas Bunzel
Adversarial robustness research has produced hundreds of defended models over the past decade, yet the literature almost universally reports robustness results in isolation: standard (clean) accuracy and
adversarial accuracy of the robust model are shown, but the gap to the corresponding vanilla model is rarely quantified. We introduce VanillaBench, a systematic
benchmark that makes this gap explicit. For every adversarially-trained model catalogued by RobustBench across four threat models, we compute the accuracy difference against multiple vanilla references from Papers with Code, computed over both all entries and no-extra-data entries, the best vanilla model as of the robust model's publication year, and an architecture-matched baseline. Across all 186 robust models, the mean delta clean relative to the best vanilla model ranges from -7.7 to -29.5 percentage points, and even the single most robust model per track still trails its temporal vanilla counterpart by 4.0-21.0 points. The architecture-matched comparison, which isolates the effect of
adversarial training from architectural differences, reveals a mean gap of -3.5 to -17.5 points. Restricting this architecture-matched comparison to models whose vanilla accuracy is known for the exact same architecture, rather than approximated from a related one, narrows the gap to -4.0 to -14.0 points. These results demonstrate that the robustness-accuracy trade-off is substantially larger than what is typically conveyed by individual papers. This information is critical for practitioners and decision-makers. When deploying models in real-world settings, the accuracy cost of robustness directly affects business outcomes, yet current publications do not provide the vanilla baseline needed to assess it. We argue that future robustness evaluations should report vanilla-referenced accuracy gaps as a standard component.
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