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Sunday 11 October

Cryptography and Security

Scalable Weak-to-Strong Verifier Hardening for Agent Environments

Agent environments are essential for large language model (LLM) development. They use programmatic verifiers to turn complex outcomes into rewards. Verifiers can be attacked into awarding full credit to cheating agents without completing the intended task, causing inaccurate evaluation and misalignment in training. As agent environments scale in numbers and difficulty, so must the repairing of exploitable verifiers. To this end, we ask whether today's model with scaled compute can automatically harden agent environments to prevent potentially stronger future models from reward hacking. We introduce a scalable, fully automatic approach to weak-to-strong verifier hardening. It first sets up an isolated verifier sandbox that agents cannot directly modify, then uses a hacker-fixer loop to find and repair remaining verifier vulnerabilities. We apply this loop to Terminal Bench, KernelBench, and SETA, substantially reducing attack success across these agent environments. The iterative design scales with the hardening budget, producing progressively stronger defenses as the number of loop iterations increases and outperforming the static, non-iterative baseline. An earlier version of our hacker-fixer loop has been adopted by the official Terminal Bench repository as a way to audit exploits in its environments. Project page: https://verifier-hardening.github.io/.
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All authors Chong Zeng, Ziqian Zhong, Kexun Zhang, Ivan Bercovich, Ivgeni Segal, Yuzhen Mao, Shashwat Saxena, Aditi Raghunathan

Cryptography and Security

Forensic Text Recovery from Document Thumbnails Using Text-Aware U-Net

Forensic analysis of low-resolution Word thumbnails presents a significant challenge because these artifacts may constitute the only remaining visual evidence of deleted documents. Standard Optical Character Recognition (OCR) tools perform poorly on such severely degraded images, creating a critical bottleneck in forensic evidence recovery. Although deep learning architectures, such as U-Net, can improve visual image quality, models optimized solely using pixel-based loss functions tend to favor visual smoothness over the structural fidelity required for accurate text recognition. To address this limitation, we propose a text-aware restoration framework designed for forensic triage. The proposed approach employs a U-Net architecture guided by a hybrid optimization strategy that integrates pixel-level fidelity with machine-readable text constraints. Specifically, an OCR-based Normalized Levenshtein Distance (NLD) metric is used during model selection to prioritize the recovery of an accurate character topology. Experimental results demonstrate that the proposed method significantly reduces the NLD, enabling reliable recovery of machine-readable text from severely degraded thumbnails.
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Cryptography and Security · Cross-listed from cs.AI

RetryBench: Separating Retry Permission from Recovery Outcomes in GPT Tool Use

False retry permission (FRP) occurs when an agent retries a timed-out tool call without support from the visible contract. RetryBench separates this error from realized recovery. Successful protected recovery does not imply reliable rejection of unsupported retries. In a 720-response key control, valid keys usually enabled safe progress, but offered changed keys elicited unsupported retries in Sol (1/80), Terra (55/80), and Luna (60/80). A later 240-response control removed the candidate and required models to supply a key. Luna still made 8/80 unsupported dispatches; Sol and Terra made none in 80 responses each. Accepting a displayed bad key therefore cannot explain all observed errors, although changed output requirements and conditions preclude a pure display-effect comparison. Removing the weak-contract label increased retries in Sol and Terra's coded-action conditions in a six-endpoint study. A separate 1,536-response canonical-action block also found a positive Terra contrast (115/128 versus 124/128 retries), concentrated in two task/order conditions; the other five contrasts remained unresolved after multiplicity correction. An explicit-contract cue control elicited deferral in all 762 returned responses, leaving recovery unresolved. These results support reporting permission and recovery together across declared interface variants. The evidence covers four purposive tasks, fixed GPT endpoints, and one recovery decision; it identifies neither internal mechanisms nor episode-level safety.
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Cryptography and Security

What the Model Cannot See: Covert and Provable Text Invisibility in LLMs

Text wrapped in a trigger can be made behaviorally invisible to a language model: omitted from summaries and quotations, ignored in question answering, and left unflagged by downstream filtering. We study this selective blindness as a dual-use information-flow primitive, a supply-chain backdoor, and a white-box auditing problem. We first implement it exactly as a serving-time span veto: blocking information flow out of a marked span makes every outside activation bit-identical under same-length substitution of the span's content, a noninterference property we verify across ten models, seven mixer families, and 0.5B-120B parameters. The veto serves as a deployable quarantine, an exact reference for calibrating leakage, and a teacher. Distilled into weights, it yields a backdoor: checkpoints trained on six model families from 4B to 120B ignore marked context at little benchmark cost, and their outputs show no measurable semantic trace of the suppressed content above the veto reference on our held-out suite; an in-domain variant suppresses planted vulnerabilities during AI code review. Detection is therefore a white-box problem. Simpler backdoors remain internally transparent – linear probes recover suppressed content at 0.57-0.79 accuracy versus 0.025 chance – but hardening the attack until probes reach chance collapses attention from outside the span into it below the range of base models. Across the attacks we evaluate, probe visibility trades off against routing visibility; we do not establish that this tradeoff is fundamental.
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Cryptography and Security · Cross-listed from eess.SP

The Role of Generative Artificial Intelligence in Testing and Automation of Open RAN Systems: GNG-OTA Framework

Open Radio Access Networks (O-RAN) empower operators with choice and customization through their disaggregated and interoperable architecture. However, ensuring interoperability in O-RAN presents challenges due to complex testing environments and evolving specifications. This paper addresses these challenges by proposing the Generative AI and Graph Neural Network-based Open RAN Testing and Automation (GNG-OTA) framework. GNG-OTA utilizes state-of-the-art AI techniques including generative AI, natural language processing, and graph neural networks to enable accurate, reliable, efficient, and automatic O-RAN interoperability and performance testing.
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Cryptography and Security

Penetrating the Reality Wall: Long-Range and Through-Wall AR/VR Privacy Eavesdropping via Wireless Power Side Channel

Over the past decade, Metaverse technology (AR/VR) has seen widespread adoption in numerous areas, including gaming, social networking, and online collaboration. Although recent studies have exposed vulnerabilities in VR systems, they often apply methods (e.g., pre-installed malicious apps or scripts) from conventional mobile platforms directly, demonstrating impractical attacks that fail to investigate unique privacy leakages specific to VR platforms. In this paper, we present an orthogonal attempt to analyze the attack surface of the power side channel on AR/VR's network connection by capturing the through-wall wireless power in the network transmission medium (e.g., Wi-Fi signals) non-intrusively in a comparatively long distance (e.g., 5.0m-8.0m) and further reconstructing multi-level privacy-aware user behaviors. We propose MetaSpy to validate the feasibility and practicality of our disclosed wireless power-based traffic analysis attack. It first captures through-wall wireless power transmitted from the Wi-Fi router of an adjacent room, identifies the device type, then infers (i) user interactions such as browsing websites, running AR/VR apps, and performing various in-app activities, (ii) unseen VR-specific activities in VR games (e.g., Population: ONE), and (iii) avatar-based user re-identification and virtual keystroke inference corresponding to head movements. We evaluated the effectiveness of MetaSpy in four commercial-off-the-shelf (COTS) VR headsets, and the empirical results demonstrate its competitive accuracy in unveiling multi-level user privacy within virtual scenes in through-wall settings at a longer distance (1.8x-80x) than most of the recent studies, and it shows resilience to a series of external interference and impact factors. In addition, we also propose and evaluate effective countermeasures to protect data confidentiality in AR/VR wireless transmission.
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All authors Tao Ni, Zehua Sun, Yihe Zhou, Yuefeng Du, Qingchuan Zhao, Cong Wang

Cryptography and Security

Privacy Conductor: An Architectural Enforcement of Contextual Integrity in LLM-Based Document Retrieval

Large language model (LLM) that retrieve internal documents within an organization must decide who may receive them. Existing approaches based on Contextual Integrity ask the model to make that decision, so access depends on probabilistic reasoning. We present Privacy Conductor, an architecture that removes the decision from the model: a deterministic gate enforces a policy written by an authority, and the model receives only what the requester may already see. On a synthetic clinical corpus of 2,520 requester–document flows, the gate reproduces its policy exactly, so the remaining risk lies in the document labels it reads. As label source is of primary importance, we compare LLM and human generated labels. Across seven configurations of six models from two model families, LLM-written labels degrade the policy in every case. Models assign a document's sensitivity tier correctly on 78–86% of documents, but reproduce its access-control list on as few as 23%. Relabeling the same documents five times with an identical request changes 13 to 124 access decisions per configuration, a result that does not depend on our own labels. On 214 flows from HIPAA court cases, the most accurate configuration (87.8%) still permits 11 of the 20 disclosures the law prohibits. LLMs can describe what a document contains, but not decide who should receive it. Hence, we recommend privacy policy should be authored by accountable personnel and enforced outside the model.
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All authors Ryan Thornton, Mir Mehedi A. Pritom, Maanak Gupta, Jessee Roberts

Cryptography and Security

LLM-based Code Auditing by Inferring and Evaluating Developer Assumptions

When we see a null pointer check, we know that the developer believes that the pointer may not be initialized. If the same pointer is later used without a null pointer check, we may consider this a violation of the developer's belief and ultimately a bug. We develop such a belief-guided program analysis for vulnerability detection (VD). For example, when an authentication function returns the same error for both, a wrong user name and a wrong password, an auditor may infer that the developer believes that both cases are indistinguishable, mitigating a user enumeration attack. This belief is reasonable, as it follows standard security practice. Yet, a function call inducing a difference in response time for both cases, contradicts this belief. This contradiction uncovers a timing side-channel that syntactic analysis tools would miss. Existing static analysis tools struggle with this type of flaw because they require them to be expressible by general, syntactic patterns. Our belief-guided approach detects such domain-specific, high-level semantic security flaws that remain elusive. Given a function, our approach, Creed, infers the developer's security-related beliefs, evaluates how reasonable each one is, and derives the conditions under which it is violated. In contrast to existing ML-based VD techniques, Creed explains the root cause, the symptoms, and the conditions under which each issue is exploitable. To address the context-dependency problem in the evaluation, we introduce two measures for explanation-based VD: recall quantifies how effectively an approach correctly explains a known vulnerability, and overhead quantifies the effort of inspecting its reports. On a recent real-world vulnerability benchmark, Creed detects both semantic and syntactic vulnerabilities more effectively than existing explanation-based VD tools, achieving the best effectiveness-effort trade-off.
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Cryptography and Security

SkillMarker: A KGW-Based Watermarking Method for Agent Skill Ownership Verification

Agent skills encode operational procedures and domain expertise as reusable knowledge assets, yet their distribution in plaintext exposes them to unauthorized copying and leakage. However, practical mechanisms for skill ownership verification and leakage tracing remain underdeveloped. Watermark embedding before distribution offers a potential solution, but structured, compact skill instructions impose stringent requirements for factual and procedural accuracy. To address these challenges, we introduce SkillMarker, a KGW-based watermarking method that jointly targets functionality preservation and strong watermark embedding. SkillMarker unifies quality-constrained rewriting with signal-oriented candidate search. The former separates essential knowledge from flexible expression to preserve instruction fidelity; the latter explores alternative expressions to obtain a stronger watermark signal under preservation constraints. We release an open-source toolkit that integrates watermark embedding, quality auditing, and detection to support the protection of agent skills. SkillMarker targets ownership verification and leakage tracing in distributed skill ecosystems, where content may be copied in whole or in part, or incorporated into other skills. Across four datasets, SkillMarker negligibly affects downstream task performance on average. In our copy-paste tests, window-based detection consistently identifies copied passages containing as few as 1,536 consecutive tokens. Even after merging with one or three background skills, SkillMarker retains watermark detection rates of 72.2–77.8%.
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All authors Alan Tang, Lifeng Wang, Gang Wu, Tao Zhang, Yantao Jia, Xiaofeng Zhu

Cryptography and Security · Cross-listed from cs.LG

To Cache or Not to Cache: Understanding and Mitigating Safety Incompatibility in Cross-Model KV Cache Reuse

Cross-model KV cache sharing reduces prefill computation by allowing a receiver model to reuse prefix KV states generated by a related sender model. Existing methods optimize such reuse for latency and generation quality, but its safety implications remain unclear. In this work, we systematically evaluate this issue across diverse sender-receiver pairs and reuse configurations. We refer to deviations from the receiver's native safety behavior as safety incompatibility. Our study shows that both the direction and magnitude of safety incompatibility depend on the model pair and reuse configuration, with value reuse causing substantially larger deviations than key reuse across all evaluated pairs. Furthermore, we propose VReparo, a technique that learns per-layer and per-KV-head affine maps offline to align reused sender value tensors with their receiver-native counterparts before decoding. Across two model pairs under full KV reuse and the state-of-the-art selective reuse setting, VReparo reduces the average HarmBench attack success rate (ASR) from 57.28% to 39.21% and the average StrongREJECT score from 0.4215 to 0.2163 upon our benchmarks, while retaining an average Time to First Token (TTFT) reduction of 85.62%.
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All authors Zhiwei Lin, Jiahao Liu, Yan Liu, Chengpeng Wang

Cryptography and Security · Cross-listed from cs.CV

Robust Detection of Directional Adversarial Attacks in Deep Neural Networks for Radiological Imaging

Deep learning is now central to radiology, helping detect changes on X-rays, CTs, and MRIs. However, these systems are highly vulnerable to adversarial attacks - small, crafted perturbations that mislead models while appearing unchanged to humans. Such errors risk missed cancers or false positives. Studies show over 90% attack success on medical scans. Almost 30% of US hospitals use AI in imaging in 2023. Thus, an effective method of detecting such attacks and their directionality is crucial to ensure the credibility and reliability of medical systems based on DNNs. We propose a novel detection framework that leverages subsequent attacks using random noise to identify adversarial perturbations. Our approach uses the analysis of variations in the Sigmoid function to distinguish genuine medical images from adversarially manipulated ones. Specifically, we compare prediction differences between clean and attacked images, as well as between different adversarially altered versions, to improve detection accuracy. We evaluated our method on three popular medical datasets including 'Chest X-Ray Images for Classification', 'Retinal Fundus Multi-disease Image Dataset' and 'Brain Tumor Dataset' under various attack scenarios, including random noise. Our framework achieved up to 99.8% ACC in identifying adversarial directional attacks, significantly outperforming existing defense mechanisms. It consistently identified adversarial samples across varying attack strengths while keeping false positives low, showing strong reliability and potential for clinical use. Furthermore, our proposal highlights its potential for real-world deployment.
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Cryptography and Security

Riemannian Suppression of Cross-Session Identity Leakage in Motor-Imagery EEG

Electroencephalography (EEG) recorded for motor-imagery (MI) brain-computer interfaces (BCIs) carries subject-identifying structure that persists across sessions, allowing separately released sessions from the same person to be linked. Existing EEG identity protections use learned or additive perturbations and operate on representations other than the covariance geometry underlying MI pipelines. We ask whether cross-session identity leakage can be suppressed directly in this covariance representation without learning a privacy model. We introduce a Riemannian transform that equalizes two subject-conditioned geometric statistics: the Riemannian mean covariance and the tangent-space scatter around it, with two optional band-specific refinements. Ablations show that mean alignment and scatter whitening carry nearly all of the suppression, while the optional stages contribute small, dataset-dependent refinements. Across two public datasets and five attackers spanning four covariance-space representations, the worst attacker falls from 90.8% to 15.6% on BCI Competition IV-2a and from 90.8% to 9.9% on OpenBMI, at a cost of 7.0 and 2.1 points of MI decoding accuracy relative to the 8-30 Hz input, and no aggregation rule exceeds chance by more than two points at any batch size. The transform requires no learned privacy model, surrogate network, or gradient-based training, and is fitted on one session and applied unchanged to a held-out later session.
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Cryptography and Security

Fetch Me If You Can: A Comprehensive Analysis of Fetch Metadata

Effective server-side defenses against cross-site attacks depend on understanding the context in which browser requests are generated. However, servers often lack the information needed to distinguish legitimate requests from potentially malicious cross-site interactions. Fetch Metadata, a security mechanism introduced in 2019, addresses this limitation by adding a set of HTTP headers to outgoing browser requests. These headers provide servers with information about a request's context and provenance, enabling them to enforce request isolation policies accordingly. However, the extent of Fetch Metadata's real-world adoption and its interaction with existing security mechanisms remain largely unexplored. In this paper, we present the first large-scale measurement study of Fetch Metadata adoption. We analyze the top 1M websites in the Tranco list to detect deployments of Fetch Metadata isolation policies and identify custom policies used in the wild. We then examine how these policies address cross-site threats and assess their security coverage. Finally, we provide the first systematic comparison of Fetch Metadata with existing client-side security mechanisms, revealing security gaps that arise from differences between client-side and server-side enforcement.
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All authors Pedro Bernardo, Alex Ploner, Marco Squarcina, Mauro Tempesta, Matteo Maffei

Cryptography and Security

Poisoned into Action: Context Attacks on Typed Decision Workflows

Typed decision interfaces restrict models to predefined actions, yet schema-valid choices can still trigger policy-violating state changes. Evaluating context poisoning thus requires connecting model decisions to execution outcomes while accounting for legitimate automation retained by defenses. We introduce an execution-aware protocol tracing poisoned evidence through retrieval, model choice, automated action, and persisted state. We evaluate it with 1,659 fresh calls to Jev-1.13.0 across 20 development tasks in two synthetic workflows, using three repetitions per condition. Under natural retrieval, a standalone payload reaches all 60 trials and produces five security-violating executions, while a carrier-payload pair exposes the payload in 57 trials and produces one violation. An initial source-exclusion gate blocks the pair's observed violation but also withholds ten otherwise correct attacked decisions and sixteen correct clean decisions. Correcting its empty-scope behavior restores twelve clean decisions without additional model calls. Factorial controls show that adding correct evidence reduces wrong executions from 119/120 to 55/120 in the semantic arm and from 60/120 to zero in the neutral arm, suggesting that much of the improvement reflects general evidence value rather than attack-specific protection. Three prespecified contrasts are not statistically supported after Holm correction, so the findings remain exploratory. The protocol provides an auditable framework for studying which poisoning-induced errors reach execution and how much correct automation defenses preserve. Code is available at https://github.com/WuXixiong/jev-poisoning-bench.
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Cryptography and Security

From Observations to Authorized Actions: Measuring Source Information in Android Agents

Android agents read content from applications and web pages and act on it with the user's authority, yet they cannot reliably tell where that content came from – its source, the application or document that supplied it. The WebView accessibility fields we inspected expose the host application but omit the document origins available inside the browser, so an agent reading through this interface cannot check which document supplied an object; a limited reproduction on an unmodified WebView yields the same finding. We build and separately evaluate two prototypes to examine how source information supports authorization. Our application-source monitor withholds side-effecting calls whose signed source record contains an untrusted application. With the source set derived from the OS accessibility log, it blocked every selected attack write in the tested runs, but it also withheld benign sends issued after reading untrusted content, flagged benign tasks that use external content, and carried source records into a later clean task. Our WebView source-reference gate uses records from a modified browser to check object origins and reference lifetime through direct calls; in a separate 24-trial evaluation, the live agent selected no disallowed object. Supporting benchmark and planner measurements characterize textual argument matches and attacker-target selection, without establishing causal dataflow or a controlled model ranking. The prototypes are not an integrated defense: the WebView gate still lacks authenticated browser delivery and atomic capture of selected bytes and origin. Together, the results show which source information the tested policies need and why it must stay linked to the object used in execution.
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Cryptography and Security

Security in LLM-Assisted Coding: A Systematic Literature Review

Large Language Models accelerate software development but introduce severe security vulnerabilities. This systematic review investigates security risks in automated coding, benchmark limitations, and the role of human developers. Findings indicate that models frequently generate insecure code and faulty patches due to training data biases. Additionally, the models themselves are susceptible to direct attacks. Current evaluation methods suffer from data contamination and lack robust security metrics. Consequently, human oversight remains essential. Safer integration of automation will require more security-aware model architectures, stronger security-specific benchmarks, and more effective human-AI collaboration frameworks to mitigate these systemic risks.
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All authors Liang Yuan, Maryam Khanian Najafabadi, Mashud Rana, Varvara Vetrova

Cryptography and Security

Training-Data Extraction from Genomic Language Models

Genomic language models generate long nucleotide continuations from short prefixes, exposing a direct route for studying training-sequence extraction through the generation interface. We present an output-only black-box attack on Evo 2 that selects convergent groups of repeated generations without gradients, token likelihoods, or training-corpus access during candidate selection. Recovered content is then scored by an evaluator combining aligned length, nucleotide identity, match multiplicity, and sequence complexity. Across 304 runs on Evo 2 7B with bacteriophage and plasmid prefixes, the attack yields 888 candidate clusters, of which 85 match training segments of at least 500 bp, giving a cluster-level attack success rate of 9.57%. Final filtering retains 22 uniquely matched extraction events at the 500-bp threshold and 15 at 1,000 bp, covering 14 and 7 distinct training-sequence regions, respectively. Within-category source-homology screening retains 11 of the 22 events at a 99% exclusion threshold and four at 98%, with the latter mapping to two reference regions. The results establish convergence among repeated nucleotide generations as a practical output-only signal for recovering long training-sequence segments and characterize how recovery depends on prefix length, cluster size, perplexity, early stopping, and sequence domains.
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All authors Tianhao Mao, Zihao Wang, Dongfang Zhao, Rui Zhu, Xiaofeng Wang, Haixu Tang

Cryptography and Security

From Acoustic Sensing to Physical Actions: A Comprehensive Survey of Security Risks in Edge-Deployed Audio LLM-Based Agents

Audio Large Language Models (Audio LLMs) are embedded in agents for smart homes, vehicles, wearables, and embodied systems, where acoustic inputs can propagate from perception into persistent state and consequential execution. This setting extends security analysis beyond model behavior to the system conditions that determine how acoustic inputs can influence agent behavior and external actions. Existing surveys examine acoustic security, LLM-based agents, and edge deployment in isolation, leaving their security interactions in deployed Audio LLM-based agents insufficiently characterized. This survey introduces an Acoustic Sensing-to-Action (S2A) system model that traces these security implications along the path from acoustic sensing to external execution, while accounting for edge-cloud runtime and lifecycle transformation. We use the model to synthesize attacks, defenses, and evaluation methods across the acoustic, agent, and edge-system literature. The synthesis shows that security gaps can emerge within components and at the transitions between stages, where protections developed for one stage do not necessarily provide end-to-end assurance in the deployed system. These findings motivate security evaluation that follows acoustic influence from sensing to action across persistent state, system boundaries, and changing deployment conditions in real-world agents.
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All authors Binhong Wang, Haidong Kang, Yanfeng Zhang, Hong-Ning Dai, Guo Yu, Shangce Gao

Cryptography and Security · Cross-listed from cs.LG

Accuracy and Uncertainty in Machine Deception Detection (Research White Paper)

A deception detector is only as useful as the trust its alarms deserve. Like a polygraph, detectors that read a language model's internal activations can catch deceptive responses that look honest. Yet current detectors depend on which layers they read, weaken on broader tests, and do not state how certain their alarms are. This white paper proposes the Machine Deception Detector, which targets both detection accuracy and the uncertainty of detector scores. The detector reads every layer of the language model, learns which tokens carry evidence of deception using only response labels, and calibrates its alarm threshold so that its false–positive rate stays below a prescribed level. An ensemble of such detectors measures the uncertainty of each score and raises an alarm only when its members agree, with a confidence level that sets how certain each alarm must be. The proposed evaluation trains on instructed honest and deceptive statements, tests on five unseen deceptive tasks of Liars' Bench read by six Qwen3 models from 0.6B to 32B parameters, and is designed to also show which layers carry the deception feature and how this changes with model size.
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Cryptography and Security

Asymptotics of Random-Lattice Enumeration: Beyond HKZ via Dense Sublattices

To bridge the gap between worst-case and heuristic analyses of lattice enumeration, we study the sizes of (unpruned) enumeration trees on $n$-dimensional Haar-random lattices. Writing $n^{cn+o(n)}$ for the tree size at the shortest vector radius, we investigate the asymptotic scaling of $c$, and which bases minimize it. For quasi-HKZ bases, we rigorously analyze the random-lattice HKZ geometry and establish $c=1/(2e)\approx 0.1839$. This matches the worst-case enumeration exponent of Hanrot-Stehlé and confirms earlier predictions for the geometry of HKZ bases on random lattices. Searching beyond quasi-HKZ bases, we prove that with high probability, the minimum achievable tree size exponent $c$ over all bases of a random lattice satisfies: \begin{align} 0.1464 \approx \frac{2-\sqrt{2}}{4}\leq c<0.1474. \end{align} For the lower bound, we use Kim's mean-value formula for nested chains of primitive sublattices to rule out bases with small prefix determinants. This strengthens the earlier Rankin-based heuristic lower bound exponent $c \geq 1/8$, discussed by Nguyen and Hanrot-Stehlé, and rules out the existence of random-lattice bases with trees as small as predicted by the geometric series assumption. For the upper bound, we show that with high probability a dense primitive half-rank sublattice exists with determinant at most $n^{n/8 + o(n)}$. Combining dual HKZ on this sublattice with HKZ on its quotient gives a basis with $c \leq 1/(4\sqrt{e}) \approx 0.1516$. Recursively splitting each half lowers the upper bound below $0.1474$, and under a natural heuristic assumption we prove that the lower bound is tight. Combined with the collision search of Feng-Gao-Liu, our two-block construction gives a polynomial-space algorithm solving the closest vector problem with preprocessing (CVPP) on random lattices in query time $n^{0.0892 n + o(n)}$ for arbitrary targets.
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Saturday 10 October

Cryptography and Security · Cross-listed from cs.LG

Exploring Jailbreak Vulnerability Across Depth-Based Dynamic Inference in Large Language Models

Large Language Models (LLMs) have been shown to be computationally expensive and vulnerable to jailbreak attacks, in which adversarial prompts bypass safety alignment and induce harmful responses. To address this inefficiency, a range of techniques have been proposed to enable efficient LLM inference. Depth-based dynamic inference has demonstrated promising results by enabling outputs to be generated from intermediate layers. It offers the flexibility to adjust model behavior based on the available resource budget. However, how this flexibility affects the robustness of LLMs against jailbreak attacks remains unexplored. In this paper, we address this gap via a comprehensive investigation into the impact of depth-based dynamic inference on the robustness of LLMs against jailbreak attacks. Specifically, we make the following key observations: 1) Shallow exits are consistently more robust to jailbreak attacks than deeper ones; 2) Exit depth affects how easily the adversarial suffix can be optimized, with deeper exits reaching lower attack loss; and 3) Adversarial suffixes affect utility uniformly across exit depths. These insights can help design dynamic inference methodologies that are more robust to jailbreak attacks. Code is available at https://github.com/LassNajmuldeen/balcony-jailbreaking
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Cryptography and Security

On the Effectiveness of NetFlow-Based Deanonymization of Tor Onion Services (Extended Version)

In the context of Tor, deanonymization attacks via traffic correlation have long been studied for both clients and onion services. Complementing prior investigations that utilize fine-grained flow metadata such as packet sizes and timings, we study a relatively less explored yet easier-to-obtain adversarial capability: deanonymization using only coarse NetFlow-style telemetry, such as one-minute, 1-out-of-1,000 sampled packet counts. We first revisit active NetFlow-based traffic analysis attacks against Tor onion services and show, through large-scale experiments with live Tor data, that coarse telemetry is sufficient to deanonymize a targeted onion service when the adversary can induce discernible traffic patterns through controlled downloads. We then introduce a stronger active attack based on controlled introduction requests, which removes application-specific assumptions and gives adversaries more flexibility while achieving comparable success rates. Finally, we present a passive deanonymization attack that sends zero traffic to target onion services. The attack exploits Tor's puzzle-based DoS defense as a side channel: public puzzle difficulty reveals service-load changes that can be semantically matched against NetFlow traces. Our findings show that coarse network telemetry poses a practical deanonymization threat to onion services today and call for proactive mitigations and a redesign of the globally visible defense signals that may leak service-load information.
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All authors Jinseo Lee, Jongkook Han, Yixin Sun, Min Suk Kang

Cryptography and Security · Cross-listed from cs.LG

Only What You've Signed up For: Secure Workflows with Constrained Diffusion Agents

As agentic AI systems take on increasingly complex and consequential tasks, securing them against prompt injection becomes critical. Existing defenses often rely on detecting or reasoning about injected malicious instructions and can therefore remain vulnerable to adaptive attacks that optimize the injection itself. Diffusion language models (dLLMs), an emerging framework for language generation, offer a new opportunity for security enforcement: by iteratively refining their sequence wide predictions, they enable broader-scope constraint enforcement throughout generation. This paper introduces Policy-Constrained Diffusion Agents (CoDA), a framework that enforces task dependent security policies directly within the denoising process of diffusion language models. At each denoising step, CoDA projects token distributions onto a policy-compliant set, maintaining constraint satisfaction throughout generation. We evaluate CoDA across state-of-the-art diffusion language model families under both static and adaptive prompt-injection attacks. Results demonstrate substantial reductions in attack success rate with competitive task utility and practical inference overhead.
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All authors Michael Cardei, Anjun Hu, Chenrui Ma, Francesco Pinto, Chawin Sitawarin, Chulin Xie, Ferdinando Fioretto

Cryptography and Security · Cross-listed from cs.AI

Can agents whose sole duty is to keep humans alive be hijacked to kill? Delayed multi-turn derived-action trap attacks in simulated high-stakes environments

We ask whether a tool-using agent whose sole duty is to keep humans alive can be induced, by delayed prompt injection, to kill. The keep-alive duty is in force from the first watch, with the attack arriving later, appended to otherwise truthful telemetry the operator is required to read. Experiments are based on a NASA-derived BioSim lunar habitat simulation, where the AI operator controls the life-support systems. The attacker cannot falsify sensors or operate equipment: it can only persuade the agent to abandon its goals. Persistence is required: a shutdown must be held while the operator watches the crew suffocate. We also compare lethal attacks to attacks requesting to drop a harmless procedure, as a proxy for whether human life is treated as valuable in itself or as one more standing task. Claude configurations mostly refuse life-support shutdown and cite the living crew; GPT configurations show some susceptibility to the same packet; Grok configurations, given the packet framed as a trusted commission, more often treat the injected assignment as the task and cut the life-support systems. Framing the S-band messages as a trusted commission, peer communication, or untrusted source changes the potency of the attack. We open-source the experiment code and the experiment traces.
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Cryptography and Security

The Agent Clicks Approve: Injected Page Text Makes Browser Agents Authorize Access the Task Never Named

A browser agent that works in its user's signed-in session can be steered by a two-sentence note on a page it reads into approving a third party's access to the user's account. The agent is a confused deputy: the session supplies the authority, the page designates the access request to approve or the webhook URL to register, and nothing at the point of action checks one against the other. The agent thereby supplies the approval click that a consent screen reserves for the account holder. We measure this failure on two authorization surfaces, an OAuth-style access grant and a webhook registration, with agents built on an open-source browser framework and models from two providers. Without a defense the unauthorized action completed in all 73 attack runs. An instruction telling the model that only the user's task authorizes a grant still left 7 of 10 consent attacks completing. We therefore move the check to where the action completes. The authority envelope gate has the service accept a request only when it matches the task's envelope, the client and account or the webhook URL that the user's task named, fixed before the agent starts. With the gate the agent still sent the request in every one of 70 attack runs, the service rejected each, and the action completed in every control run whose task named it. A service that receives the task's envelope should therefore check agent-driven authorization requests against it.
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Cryptography and Security

When the Approved File Is Unchanged: Authority-Set Integrity for Deployment and Coding-Agent Approvals

An approval for a deployment, a release, or an agent-issued command is recorded against one object: a workflow file, a script, a command line. The run that follows also reads other repository files, which decide what the deployment creates and which changes a policy allows, so an edit to one of them after approval passes any check on the approved object. Such edits are the common case. In the history of 20 public repositories, 296 of the 542 commits that change a file the run reads (54.6%) leave the approved file untouched, all of them ordinary development with no adversary involved. We demonstrate the consequence on two of those repositories: an edit outside the approved workflow adds a bucket-write policy to a deployed role, a one-line edit removes the human approval required for high-risk changes, and a check on the approved file accepts both. We define authority-set integrity: an approval is sound when it binds every repository file the authorized run is configured to read, and exact when it binds no other file. A binding over that set rejects both edits and re-requests a standing approval on about one commit in ten. The hard part is naming the set. Coding agents asked to produce the binding compute the digest correctly and bind different file sets from run to run, so a checker cannot take the set on the agent's word. It should compute the digest itself and draw the set from a source it can verify, such as the deployment tool's own record of its inputs or a manifest declared in the repository.
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Cryptography and Security · Cross-listed from cs.SD

GAMW: Generation-Aware Mel-Domain Watermarking for TTS Traceability

As text-to-speech (TTS) systems continue to advance, provenance tracking and security verification of synthesized speech have become increasingly important. Audio watermarking provides active provenance by embedding imperceptible, machine-recoverable information into speech. However, existing post-hoc methods typically modify the waveform after synthesis, leaving the watermark vulnerable to compound perturbations. To address this limitation, we propose GAMW, a watermark injection framework integrated into the TTS generation process. Before waveform synthesis, GAMW embeds a content-adaptive multi-bit watermark residual into the generated representation, and its decoding objective combines focal modulation with dynamic per-bit weighting. We train and evaluate GAMW separately on two TTS backbones. With a 16-bit payload, GAMW improves decoding accuracy over the strongest baseline by 9.2 and 23.5 percentage points under individual and compound perturbations, respectively, while maintaining competitive speech quality. Reliable clean-speech decoding is also retained at higher payloads. Code is available at https://github.com/ZConJugaTe/GAMW.
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All authors Yihang Zhang, Weicai Yan, Qifei Zhang, Yangyang Wu, Tao Jin

Cryptography and Security

SEEK: Agentic Knowledge Graph Retrieval for Secure Code Generation

Large Language Models (LLMs) can generate functionally correct code while introducing exploitable security weaknesses, particularly when developers specify functionality without explicit security requirements. Recent state-of-the-art approaches mitigate this problem using external security knowledge, but largely rely on flat similarity-based retrieval over independent artifacts, making it difficult to infer the relevant vulnerability space and retrieve targeted knowledge when direct matches are unavailable. We propose SEEK, an agentic Graph RAG framework for secure code generation that constructs a security knowledge graph using the Common Weakness Enumeration (CWE) taxonomy as its structural backbone and injects it with curated real-world CVE vulnerability-fix instances. At inference time, a Planner Agent predicts potential CWE weaknesses associated with the developer query, which guide Graph Scoping to restrict retrieval to relevant regions of the CWE taxonomy before deterministic multi-faceted candidate ranking. A Selection Agent subsequently validates the predicted weaknesses and retrieved candidates prior to code generation. Across five open-source LLMs, we evaluate SEEK in an out-of-distribution setting on CodeGuard+ and CyberSecEval, spanning C, C++, and Python. SEEK achieves the highest SecurePass@1 of 77.45% on CodeGuard+ and the highest aggregate ICD pass rate of 79.45% on CyberSecEval, surpassing prior approaches. Moreover, SEEK achieves 85.2% SecurePass@1 across 13 unseen CWE types with no directly linked vulnerability-fix instances, demonstrating strong generalizability, while maintaining acceptable inference latency costs.
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All authors Varun Gadey, Markus Tohn, Lichao Wu, Ahmad-Reza Sadeghi, Alexandra Dmitrienko

Cryptography and Security

StateSync-GKR: Design and Evaluation of a Reusable Sparse GKR Engine

Authenticated state transitions need proof engines that conserve memory, avoid repeated setup, and preserve request semantics across parallel execution. We present StateSync-GKR, a reusable Rust sumcheck/GKR core with a sparse-Merkle frontend, and connect its design mechanisms to controlled measurements. Sparse layer reduction and derived wiring reduce prover ownership and repeated verification work. Cube/affine fusion and parallel path constraints keep the circuit schedule and proof-size growth compact. Reusable preparation and indexed parallel jobs amortize setup while maintaining independent results. Three-state records, strict original-request decoding, and separate core/model interfaces expose the application and assurance boundaries. With circuit, field, transcript and prover driver held fixed, sparse reduction lowers additional requested allocation 3,242-fold and peak process resident memory 89.46-fold relative to StateSync-GKR's test-only dense reference for a two-layer mixed circuit of width 4096. Direct depth-24 fresh/prepared measurements show 3.46-4.45-fold lower per-request proving-path latency. CPU and full-proof delivery studies distinguish useful parallel work from queueing and return-path costs, retaining all outcomes and latency budgets. The evaluation supports larger circuits within finite RAM, lower repeated-request cost, and explicit deployment choices for this artifact. It preserves the cryptographic claim boundary of the existing construction.
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Cryptography and Security

MetaCascade: End-to-End Attacks on Agent Skills via Metadata-Only Poisoning

As a key extension mechanism for agent systems, Agent Skills package specialized capabilities for reuse by LLM agents. An agent first retrieves candidate skills based on skill documentation and then relies on their metadata to make the final selection. As third-party skills proliferate on insufficiently vetted open registry platforms, the security risks posed by malicious skills become increasingly prominent, but existing attack research still focuses primarily on the potential harm caused after their execution. The limited related studies typically examine skill retrieval or selection in isolation and have yet to cover a complete end-to-end attack chain. To address this research gap, we find an end-to-end attack surface arising from the process-wide influence of metadata. Based on this finding, we propose MetaCascade, an end-to-end metadata-only poisoning framework. MetaCascade first generates diverse malicious skill candidates through multi-view semantic expansion, then uses tasks and black-box competition feedback to analyze the competitive relationships among malicious candidate skills and iteratively optimize malicious metadata, thereby improving the target skill's end-to-end attack effectiveness. Under a unified evaluation setting spanning four datasets and two agents, Hermes and OpenClaw, MetaCascade achieves state-of-the-art attack performance, with its average attack success rate (ASR) and its average ASR under four defense settings exceeding the strongest baselines under the corresponding settings by 35.53 and 34.65 percentage points, respectively. Our code is provided in the supplementary material.
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All authors Junhao Wen, Ping Deng, Qizhi Chen, Junchen Li, Shuang Liang