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Sunday 27 September

Cryptography and Security

GenoTrace: Inheritable Watermarks for Genome Foundation Model Distillation

Can a genome model retain a detectable record of the synthetic sequences used to train it? We study watermark inheritance through distillation with GenoTrace, a codon-aware extension of green-list watermarking. Two token-level factors modulate the teacher's generation bias using codon position and organism-specific codon usage. The resulting sequences train a smaller student, whose outputs are audited without an active watermark processor. In a three-seed GenomeOcean-500M-to-100M experiment, the joint configuration achieves a mean audit score of 17.88 and 94.5% detection at a fixed threshold. It retains 49.0% detection after key-aware token substitution, compared with 0% for the available single-seed plain-watermark comparator, and 47.0% after combined mechanism-targeted nucleotide edits. Additional experiments establish inherited signal across five organism-conditioned datasets and teacher-student size ratios up to 40. Component ablations and computational sequence-quality assays reveal distinct operating points for detection strength and coding coverage. GenoTrace provides a practical token-level construction and an empirical account of how genomic structure shapes inherited watermark signals. The findings concern shared-tokenizer distillation and the tested editing procedures, with calibration and biological utility treated as separate evaluation requirements.
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Cryptography and Security

PerceptFence: Content-Mediation Architecture and Deterministic Coverage for Screen-Share AI Assistants

Live screen-share AI assistants observe raw screen and speech streams, but users have little runtime control over what an assistant may observe, retain, or disclose. Prompt-level privacy settings are insufficient because sensitive content enters through the capture stream. We present PerceptFence, a content-layer mediation architecture between capture, memory, and model responses, with a deterministic synthetic-fixture scaffold; the artifact omits live capture, category inference, authenticated re-consent, cross-session state, and an external model adapter. On 9,600 protocol-documented adversarial strings scored by a separately implemented exposure oracle, PerceptFence neutralises 0.828 of digit-PII payloads on the 5 seeds both systems run, versus 0.183 for Microsoft Presidio; outside that family Presidio leads 0.238 to 0.154, so the overall 0.398 to 0.260 comparison is only indicative. We then evaluate the path a deployed assistant uses: 480 synthetic developer-support screens rendered by Chrome, degraded, and read by OCR, with rules frozen before testing and three screen types held out. PerceptFence neutralises 889 of 968 OCR-surviving secrets and PII values (0.918; Wilson 95% 0.899-0.934) against 0.581 for Presidio and 0.179 for gitleaks, and 0.974 on the held-out screen types, at a measured cost of 0.763 task-token retention on those types. The contribution is a documented mediation architecture and an evaluation method with explicit coverage boundaries, not a claim of live deployment, formal privacy, novel redaction primitives, or general model robustness.
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Cryptography and Security

DeMark: A Query-Free Black-Box Attack for Quality-Preserving Audio Watermark Removal

Audio watermarking protects digital speech by embedding imperceptible signals for ownership verification and misuse tracing. However, the security of learning-based watermarking remains insufficiently understood under realistic adversarial removal, where attackers cannot access or query the watermark encoder, decoder, or detector. Existing attacks either rely on model feedback, require clean-watermarked pairs, or reconstruct the waveform with generative models, often leading to high query costs, limited generalization, or degraded perceptual quality. In this paper, we propose DeMark, a query-free black-box attack for quality-preserving audio watermark removal. Our key insight is that watermark embedding, while perceptually hidden, can introduce subtle non-speech artifacts in the time-frequency domain that are not fully aligned with natural speech. DeMark removes watermarks by suppressing these artifacts through two stages: Diverse Artifact Learning, which extracts complementary non-stationary and stationary artifact patterns, and Adaptive Artifact Scaling, which adaptively combines and amplifies them under quality-preserving constraints. Across two speech datasets and four state-of-the-art watermarking methods, DeMark achieves average attack success rates of 0.92 and 0.96 while consistently preserving higher perceptual quality than existing adaptive attacks. These results reveal a practical vulnerability of current audio watermarking systems and call for more robust watermark designs against query-free adversarial removal.
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All authors Weikang Ding, Binhao Ma, Hanqing Guo, Rui Duan

Cryptography and Security

GateDrain: Availability Attacks and Admission-Side Defense for Confidence-Gated Edge-Cloud Inference

Confidence-gated edge–cloud inference accepts confident local predictions and offloads uncertain inputs to a stronger cloud model. We show that this routing decision creates an availability attack surface. We call this attack GateDrain: bounded input perturbations lower calibrated confidence and redirect requests that would otherwise be answered locally into a shared cloud queue, without increasing the application request rate. Because escalated requests share a cloud service, an increase in per-request cloud demand can move a near-capacity deployment across a queueing knee, causing disproportionate tail-latency degradation for benign users. We evaluate white-box, transfer, decision-only, universal, and multi-gate attacks on the public EdgeBoost artifact. A fixed-application-volume comparison isolates the effect of confidence manipulation from added client traffic, while perturbation-budget and arrival-process sweeps show that the queueing transition persists across several workload models but its amplification depends on the operating point. Adaptive attacks also defeat the evaluated training-free preprocessing defenses. To contain the resulting cloud demand, we evaluate Bounded Escalation, which combines per-source admission budgets, protected capacity, and non-preemptive trusted-class priority; an optional global bucket adds an identity-independent bound on untrusted admissions. The evaluation makes the resulting policy trade-off explicit: authenticated clients receive latency isolation, whereas tighter aggregate containment can reject legitimate unauthenticated offloads and reduce overall expected accuracy through edge fallback.
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All authors Zonghua Gu, Julian Singh-Smith, Junlin Liao, Di Liu

Cryptography and Security

The Privacy Fallacy of Crowdsourced Fine-Tuning: Extracting Proprietary Data via Topic-Based Poisoning

Supervised fine-tuning (SFT) is widely used to adapt large language models to downstream tasks. Crowdsourcing user conversations is an established approach to collecting SFT data at scale while reducing the need for costly manual annotation. However, it also allows untrusted users to contribute data to the fine-tuning pipeline. We investigate an underexplored privacy risk arising from this setting: can a malicious user poison a small fraction of the crowdsourced data to amplify extraction of previously unseen instructions contributed by other users? We show that this is possible using only black-box, output-only access to the deployed model. Experiments across four models and two datasets demonstrate substantial increases in training-data extraction: with only 50 poisoned examples, near-verbatim extraction reaches $3.71\times$ the rate without poisoning for Qwen2.5-14B on OpenMathInstruct and $3.08\times$ for Llama-3.1-8B on AceReason. Data filtering also proves largely ineffective in detecting poisoned samples: even the best-performing method achieves only 0.378 in F-1 score, leaving the majority of poisoned samples undetected. These findings demonstrate that seemingly benign crowdsourced contributions can amplify leakage of other records while remaining difficult to identify through data filtering.
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Cryptography and Security

TrackFlood: Relocating Latency Attacks from NMS-Free Detectors to Real-Time Trackers

We consider latency attacks on object detectors, where the attacker's goal is not to corrupt a prediction but to make the system fail to respond in time, targeting real-time applications such as autonomous driving. Modern object detectors eliminate Non-Maximum Suppression (NMS) through one-to-one assignment or set prediction, removing the classical detector-side latency bottleneck exploited by prior latency (“sponge”) attacks. We show that NMS-free does not mean latency-robust: this architectural change does not eliminate the attack surface but relocates it downstream to multi-object tracking, whose data-association cost remains content dependent. We present TrackFlood, a unified white-box overload attack against NMS-free detect-then-track pipelines spanning both one-to-one detectors (YOLOv10 and YOLO26) and query-based detectors (RT-DETR). TrackFlood recovers differentiable confidence tensors and optimizes perturbations that flood the tracker with spatially distributed phantom detections while leaving detector inference unchanged. Evaluated entirely on an NVIDIA Jetson AGX Orin (TensorRT FP16), detector latency remains essentially constant, whereas tracker latency increases substantially. At a standard imperceptible budget ($L_\infty{=}8/255$), a universal perturbation produces clearly measurable tracker overload but only modest end-to-end slowdown, without deadline misses for the association-dominated trackers; a separate higher-budget stress test drives severe end-to-end slowdowns and sustained deadline misses. We further evaluate a lightweight, architecture-agnostic bounded-admission layer that caps the tracker workload and largely restores end-to-end latency, at a non-trivial cost in admitted clean detections. Our results demonstrate that evaluating NMS-free perception systems requires considering downstream tracking and end-to-end timing, not detector inference alone.
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All authors Zonghua Gu, Julian Singh-Smith, Junlin Liao, Di Liu, Amin Saremi

Cryptography and Security

A2A-ForensicTrace: Offline Verification of Tamper-Evident A2A Runtime Evidence

Security-relevant Agent2Agent (A2A) executions can cross organizational boundaries, leaving investigators without live access to all participating systems. Offline investigation involves checking preserved records and their cross-record relationships for consistency. This paper presents A2A-ForensicTrace, an offline verification layer that converts runtime observations into typed records, derives protocol-relevant relationships, and commits both under an incident-trace root. An Ed25519-signed receipt binds the root and capture digest to the incident context. Evaluation comprised 240 executions through the official A2A software development kit (SDK), with actions selected by a large language model (LLM). These included 120 condition runs and 120 matched controls. All condition runs returned the expected bounded findings. No control produced an indication, and all roots and receipts verified. Median in-memory latency of the full offline verifier was 1.61 ms for the scenario traces. In the separate scaling experiment, it was 30.85 ms at 1,000 committed leaves. Future work will broaden A2A lifecycle coverage.
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Cryptography and Security · Cross-listed from cs.LG

Training Witnesses: Trusting the Training without Trusting the Trainer

Progress in machine learning cannot outpace our ability to verify it. With an explosion in papers today, every scientific claim rests initially on trust in the trainer, leading to uneven evaluation, baselines, and forestalling of reliable progress. Traditionally, the burden of verification falls on the reader, who must reproduce expensive training runs. This strategy is impractical due to an explosion in slop contributions, diversity of methods, and the sheer compute required. We put the burden of proof where it belongs, on the trainer, and in the process also cut the overall cost of verification significantly. We introduce Witnesses, a method for certifying training, data usage and evaluation in a neural network training run. Our key insight is that fast behavioral fingerprints with occasional replay challenges are sufficient for auditing neural network training. Our method is applicable at scale with minimal overhead to the trainer, is cheap for the verifier, rejects bad training runs with amplifiable probability, and allows for exact queries of both data inclusion and exclusion. We test our method on language model training runs from 100M to 2B scales, across DDP and FSDP, and demonstrate this minimal overhead. We also introduce a self-regulating leaderboard of "auto-certified" training runs that enables shared baselines and progress. We invite the community to participate in the leaderboard to improve reproducibility in machine learning.
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Cryptography and Security

A2A-CaseVerify: Merkle-Linked Case-Evidence Verification for Cross-Organization A2A Workflows

Agent-to-Agent (A2A) communication enables large language model (LLM) agents to exchange tasks, messages, and artifacts across organizations. A valid message alone does not establish that a final workflow claim is supported by a complete, ordered, and case-consistent evidence path. We present A2A-CaseVerify, a deterministic offline verifier that maps preserved A2A runtime objects, business events, and typed support edges to a directed case evidence graph. It commits A2A envelopes, event projections, and support edges, then combines event and edge leaves into a deterministic case Merkle root. The verifier returns SUPPORTED with status OK only when protection and profile-specific reconstruction checks pass. We evaluate one canonical supported healthcare-profile bundle and 13 controlled mutations. We separately test a valid bundle generated with the official Python A2A software development kit (SDK). In these tests, the canonical and SDK-generated bundles are accepted. All 13 mutations are rejected, and each returned reason-code set contains its targeted diagnostic code. A2A-CaseVerify adds offline case-level evidence-support verification to A2A interoperability.
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Cryptography and Security

Near-Duplicate Families Break Exact-Record Membership Inference

Membership inference (MI) asks whether a specific record appeared in a model's training set and is increasingly used as evidence for data provenance and copyright auditing. These applications require determining whether the exact queried record was used for training, rather than merely whether the model was exposed to similar content. Making this distinction is challenging because web-scale datasets naturally contain near-duplicates, including syndicated articles, mirrored pages, and lightly modified images. We show that this creates a fundamental confound for standard MI. A clean-reference audit typically calibrates membership against a null in which neither the queried record nor its near-duplicate family is present. In deployment, however, the queried record may be absent while a non-identical family member was used for training. We introduce a four-world audit that independently varies exact-record inclusion and family presence to separate these cases. Natural near-duplicate families cause severe false attribution. On CC-News, a clean-reference LiRA auditor labels 99.70% of family-present exact non-members as members at 1.00% false-positive rate. This failure persists across alternative scores, model architectures, and executed deduplication and retraining. Controlled interventions further reveal that the effect depends on the learning objective. In classification, faithful families largely substitute for the exact record, reducing exact-given-family inference to near chance. In autoregressive language modeling, the exact sequence retains a detectable residual, while family presence still confounds clean-reference decisions. These results show that positive model-only membership evidence may establish family-level exposure without establishing exact-record provenance.
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All authors Yiyong Liu, Jiayang Liu, Yixin Tan, Lu Sun, Rui Wen

Cryptography and Security

Can Prompt Anonymity Protect Your Identity From LLM Providers?

User conversations with large language models (LLMs) often contain highly sensitive personal information that can be exploited by LLM providers to create detailed user dossiers, enable targeted advertising, and train more powerful models. To protect user privacy, anonymizing LLM proxies have emerged as a practical solution that separates user identity from their prompts, yet this approach still leaves the prompt content visible to LLM providers. We study the impact of this gap by conducting the first empirical investigation into the risk of prompt authorship re-identification. Towards this end, we create PromptAnonBench, a novel benchmark for evaluating prompt anonymity, consisting of over 175,000 cleaned, authentic multi-turn user prompts from various real-world datasets (SWE-Chat and WildChat). Using the embeddings of historical user conversations, an attacker can correctly detect and re-identify at least one anonymized conversation for 50–75% of SWE-Chat users and up to 10% of WildChat users at a 10% false acceptance rate for out-of-set users, even with text-based defenses applied. Our findings unveil the risk of relying only on anonymity for private LLM inference and the gap in existing text privacy defenses.
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All authors Dzung Pham, Dillon Sheils, Naina Singh, Amir Houmansadr

Cryptography and Security · Cross-listed from cs.LG

No Free Efficiency: Revisiting the Trade-off Between Training Efficiency and Model Vulnerability

Training efficiency has become the central driver of recent progress in foundation models. To overcome the massive computational and data requirements of large-scale training, researchers increasingly adopt strategies such as selective data sampling, efficient pre-training, and simplified reinforcement learning pipelines. While these strategies drastically reduce overhead, they prompt a critical, yet neglected question: Is efficiency achieved at the expense of model robustness and security? To our knowledge, we present the first systematic cross-domain investigation of the efficiency-vulnerability trade-off. Across vision and language models, we show that efficiency-oriented training increases susceptibility to adversarial and privacy attacks. We characterize this vulnerability by analyzing the models' internal geometry and functional representations, demonstrating that the evaluated efficient variants consistently exhibit sharper loss geometry together with systematic changes in representational structure. We further extend our analysis to "zero RL training", finding that models trained using simplified RL recipes exhibit substantially greater susceptibility to catastrophic forgetting and more pronounced overconfidence than those trained through conventional alignment pipelines. Our findings suggest that training efficiency is rarely a "free lunch"; rather, the mechanisms that minimize computation can inadvertently compromise safety. We conclude by calling for a paradigm shift toward multi-objective training that jointly optimizes for performance, cost, and security.
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All authors Yiyong Liu, Jun Sakuma, Michael Backes, Rui Wen

Cryptography and Security

The Cost of Stability: Deanonymizing Onion Services Long-Lived Introduction Circuits

Tor is a widely used anonymity network that provides network privacy by routing client communications through a sequence of relays to their destinations. An adversary observing a single Tor relay cannot readily link clients to their destinations, as doing so requires identifying the other relays along the client circuit. Identifying these relays from traffic observed at the monitored relay alone is challenging: each relay carries traffic for many circuits simultaneously, and client circuits typically last only about 10 min, limiting observations of a given circuit. In contrast, Tor onion services use introduction circuits that remain fixed for 18 to 24 h. We develop an intersection attack that exploits this design, allowing an adaptive adversary observing one Tor relay at a time to identify the network location of an onion service. We evaluate the attack on the live Tor network against a self-operated onion service carrying genuine third-party traffic. Across nine end-to-end experiments, the attack reconstructs the complete Tor circuit in every run, with an estimated median time of 2.2 h. To mitigate this attack, we propose a mechanism that periodically rebuilds internal introduction circuits to limit evidence accumulation without changing publicly advertised information.
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Cryptography and Security · Cross-listed from cs.SE

RAISE: Reinforcing Access Control Policy Synthesis in LLMs via Symbolic Evaluation

Translating natural-language access-control requirements into policies requires careful reasoning about permissions, constraints, and exceptions, and even frontier LLMs often produce policies that violate the intended authorization semantics. We construct CedarInstruct, to our knowledge the first dataset that supports both training and semantic evaluation for formally verifiable Cedar policy synthesis. It contains 5,800 scenarios across 44 domains and 1,408 representing a single synthetic organization, each with a verified target policy and an executable verification plan. On this data we introduce RAISE, which trains policy synthesizers from formal verification in two stages, verified supervised fine-tuning (SFT) followed by a reinforcement learning (RL) stage that learns from verifier signal. We find that SFT succeeds largely by letting models express authorization logic they already have, since untrained models rarely write valid Cedar but often reason correctly when they do. After SFT, how the verifier's information is used matters more than how much of it is used. Of six RL instantiations that consume progressively richer verifier signal, only RAISE-OC improves meaningfully on SFT; it turns failed checks and symbolic counterexamples into guided exploration and learns from the result with off-context GRPO. With about 5.4K verified scenarios and LoRA fine-tuning, RAISE-OC trains Qwen3.5-9B to surpass zero-shot GPT-6 Astra and Claude Opus 5 by 13.33 and 16.26 percentage points in semantic success on held-out scenarios, and training transfers to the independently constructed CedarBench.
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Cryptography and Security · Cross-listed from cs.SD

Tokens Change, Structure Endures: Spectral Watermarking for Generated Speech

Watermarking is a promising tool for establishing the provenance of AI-generated speech. While many neural audio watermarking methods rely on a separately trained watermark generator, token-level watermarking is a training-free alternative that operates directly during generation. Its main weakness is retokenization: decoding generated speech to a waveform and encoding it again can change token identities and erode the watermark. To make the watermark robust to these changes, we propose Redwing, REtokenization-Durable Watermarking IN Generation. It builds a graph from the token substitutions observed under retokenization, whose Laplacian yields a basis that assigns similar values to tokens likely to substitute for one another. Over this basis, embedding and detection functions are jointly optimized to preserve watermark signal through retokenization while limiting embedding distortion and detector variability on unwatermarked speech. On the Moshi full-duplex system, after eight consecutive passes of Mimi resynthesis, Redwing achieves 80.7% TPR at a calibrated 1% FPR, compared with 8.3% for KGW and at most 7.3% for WMAR. It also has the highest TPR after eight passes through three other neural codecs (77.5-93.0%), and the gains generalize to TTS models at a speech-quality cost close to that of KGW. These results show that retokenization is not merely a source of noise: its transition structure can be exploited as a design principle for robust token-level watermarking.
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Cryptography and Security

SecProbe: Adaptive Evaluation of Coding Agents on Cybersecurity Vulnerabilities

Assessing cybersecurity vulnerability awareness in coding agents requires evaluations that reveal capability gaps and remain informative as models evolve. Static benchmarks offer fixed coverage and difficulty, while scarce vulnerable repositories and costly expert authoring limit their renewal at scale. We introduce SecProbe, a framework for adaptive evaluation that combines Item Response Theory (IRT) with on-demand synthesis of repository-scale vulnerability-repair tasks. From observed performance, SecProbe estimates agent ability and identifies where additional evidence is most informative, selecting existing tasks or synthesizing new ones accordingly. As one use case, we construct 353 tasks spanning six programming languages and 151 CWE types and evaluate nine frontier models with two agent harnesses. Success rates peak at 28.33%, highlighting substantial gaps in vulnerability recognition and repair. Compared with random and one-shot baselines, SecProbe achieves comparable agent ability estimates while requiring agents to solve up to 29.5% fewer tasks. These results support adaptive evaluation as an efficient and discriminative approach to assessing cybersecurity vulnerability awareness.
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All authors Xiaonan Luo, Yue Huang, Kehan Guo, Ping He, Chuan Zou, Chujie Gao, Lichi Li, Yuchen Ma, Zhangchen Xu, Zichen Chen, Yufei Han, Xiangliang Zhang

Cryptography and Security · Cross-listed from cs.CV

MAD-Guard: Controlled Study of Autoregressive Generation versus Direct Decision Interfaces for Closed Multimodal Forensic Tasks

When should multimodal foundation models generate tokens, and when should they directly output a decision? We present MAD-Guard, a controlled study of output-decision interfaces for closed multimodal forensic tasks. Once a multimodal representation is computed, is autoregressive generation necessary for closed forensic decisions with high input complexity but low output entropy? Under a matched Qwen3-VL-8B backbone, 2,400 FakeClue training samples, and LoRA budget ($r=16, \alpha=32$) on Huawei Ascend 910C NPUs, we evaluate a progression of decision interfaces (AR-SFT [generate] $\to$ Logit Slice $\to$ Binary Direct Head $\to$ +choice $\to$ +act $\to$ CLM-Head) and decompose latency into backbone representation (53.12 ms), 151,643-way vocabulary projection (+85.04 ms $\to$ 138.16 ms), and decoding (+248.26 ms $\to$ 386.42 ms). Under 1-to-1 binary supervision ($\mathcal{L}_{\mathrm{BCE}}$), a Binary Direct Head cuts latency by $2.60\times$-$7.27\times$ (53.12 ms) and lowers calibration error by $1.88\times$ (ECE = 0.0450 vs. 0.0845), with a -1.80% accuracy trade-off (93.10% vs. 94.90%; 0.9795 vs. 0.9871 ROC-AUC) from forfeiting token priors. Gains above AR-SFT arise either from multi-task attribution and uncertainty gating (+choice+act: 96.44% accuracy, 0.9940 ROC-AUC, 0.0187 ECE at 53.71 ms) or from a disaggregated contrastive head (CLM-Head: 96.55% binary and 96.44% multi-task accuracy, 0.0166 ECE, 98.79% 7-class attribution at 54.42 ms) retaining semantic priors without token decoding. Across 5,000 out-of-sample images from five benchmarks, our framework excels on synthetic, camouflage, and document forgeries (96.44% GenImage, 97.73% Chameleon, 91.84% Doc) while showing a clear boundary on compressed face manipulation (FF++ ROC-AUC = 0.5913).
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Cryptography and Security

COGNIT-Guard: Calibrated Standalone Direct-Decision Guardrails with Heterogeneous CPU-NPU Confidence Cascading under Explicit Latency and False-Positive Constraints

When must a foundation-model safety gateway generate tokens, and when should it directly output a calibrated decision? We study calibrated standalone direct-decision foundation models for real-time pre-ingestion safety guardrails, jointly addressing probability calibration, dual-use false-positive control, and heterogeneous CPU-NPU routing under explicit latency SLOs. Pre-ingestion guardrails must screen prompts prior to target-LLM prefill with low false alarms on benign compliance inquiries; however, shallow classifiers are brittle to phrasing shifts, hidden-state probes require coupling to a target LLM, and generative guards incur high decoding latency and dual-use false positives. We present COGNIT-Guard, coupling a validation-calibrated CPU fast gatekeeper with confidence-gated escalation to an NPU-resident 322M bidirectional direct-decision model (Laya-322M) under an asymmetric false-positive penalty. On the clean unseen DUCS-Bench test split ($N=607$), COGNIT-Guard achieves 98.85% accuracy (McNemar $p = 1.19 \times 10^{-4}$ vs. ML), reduces benign FPR to 0.42% ($1/238$; Fisher's exact $p = 8.23 \times 10^{-4}$ vs. ML), and attains 1.12% ECE and 0.0104 Brier score. On Huawei Ascend 910C NPUs, pure NPU inference runs in 21.77 ms mean latency (45.90 QPS), while the live serial CPU-NPU cascade ($\theta^*_{\mathrm{deploy}}=0.70$) achieves 41.63 ms mean latency (P50: 39.47 ms, 99.23% accuracy, 0.00% FPR). Evaluation on SafetyBench-ZH ($N=2,100$) and comparison against a bi-encoder direct-decision baseline (CLM-8B) disentangle in-domain gains, OOD alignment tax (60.33% $\to$ 56.81% on Laya; 55.10% on domain CLM-8B), and experience replay recovery, restoring OOD accuracy to 64.10%-65.05% and reaching 99.67%-99.84% in-domain accuracy with 0.00%-0.42% FPR.
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Cryptography and Security · Cross-listed from cs.LG

Climbing the Hill: Prompt Injection Red-Teaming Against Frontier Models with Curriculum Reinforcement Learning

Prompt injection is a leading security risk for LLMs and LLM-based applications such as agents. State-of-the-art red-teaming methods for prompt injection leverage reinforcement learning (RL) to train an attacker LLM to generate effective injected prompts. However, when targeting frontier LLMs such as GPT-6-Luna, a major challenge is the cold-start problem: every attack attempt by the attacker LLM fails and thus receives zero reward, providing no signal for learning. In this work, we propose a curriculum learning-based method to address the cold-start problem. In particular, we propose to train the attacker LLM against a sequence of increasingly robust target LLMs, with each stage warm-starting from the attacker LLM obtained in the previous one. However, simply training against a weak target (e.g., GPT-4o-mini) may not sufficiently prepare the attacker LLM to obtain useful learning signals against a frontier LLM (e.g., GPT-5.6-Terra). Instead, we find that the design of the curriculum is critical: after each stage, the attacker LLM needs to partially succeed against the next target LLM such that it can learn from successful attempts to attack the new target. Our extensive evaluation shows that our method can effectively red-team frontier LLMs, achieving an attack success rate (ASR@10) of 93.8% and 45.0% against GPT-5.6-Luna and GPT-5.6-Terra on AgentDyn, whereas state-of-the-art RL methods such as RL-Hammer and PISmith achieve 0% ASR under the same setting. Moreover, we find that the attacker LLM transfers across targets, e.g., an attacker LLM trained to defeat one strong LLM (GPT-5.6-Terra) also succeeds against six other frontier LLMs (e.g., GPT-6-Luna) it was never trained on. Our code is available at https://github.com/albert-y1n/PIForge.
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All authors Chenlong Yin, Xiaolong Jin, Wei Zou, Yanting Wang, Jinyuan Jia

Cryptography and Security

The Price of Peeking: Anytime-Valid Leakage Detection on ML-KEM EM Traces

Side-channel evaluators routinely inspect leakage tests while acquisition is still running, and extend or stop the campaign based on what they see. Fixed-horizon screening such as the Welch $t$-test with threshold $|t|>4.5$ gives no error guarantee for this monitored decision rule. We study anytime-valid leakage detection based on testing by betting: SKIT-type swap-pair e-processes whose false-alarm probability is controlled uniformly over time under an explicit conditional symmetry null. In matched comparisons that share the frozen witness, rows and payoff, first-crossing detection needed 1.68-2.00$\times$ the traces of a fixed-horizon randomization test at 80% detection on synthetic streams, and 1.68-2.38$\times$ on degraded recordings from an open ML-KEM electromagnetic dataset with the primary Ridge witness at $\alpha=0.05$. With the same primary witness and level, on undegraded reference and pqm4 recordings the monitored procedure stopped early: its median stopping point was 62-72 and 146-316 evaluation traces, i.e. 2-8% of a conservative 4096-trace budget. Under exact designed nulls on the recorded backgrounds, repeated-look $|t|>4.5$ screening over all 13000-20000 samples raised a false alarm in 2.7-12.9% of replicates, against 0.0-4.7% for terminal-only screening and no rejection by a sample-wise e-Bonferroni process, which in a prespecified follow-up detected natural-label associations in 4 of 4 backgrounds after 840-3288 traces. All recordings come from one device, and natural-label results are descriptive; we state the assumptions each claim requires.
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Cryptography and Security

Information Blackhole: Exploring Backdoor Mechanism in 3D Point Cloud Reconstruction

Point cloud autoencoders are fundamental components for 3D world representation and support many safety-critical downstream applications. Existing studies have extensively investigated backdoor attacks on point cloud classification, whereas backdoor attacks against point cloud autoencoders remain largely unexplored. However, their backdoor behaviors differ substantially due to the intrinsic structural gap between discriminative and generative models. Specifically, a classifier is a discriminative model that separately fits the marginal distributions of benign and malicious data. In contrast, the generative nature of an autoencoder entangles the two within a unified latent distribution, leading to information crosstalk and reduced attack controllability. In this setting, residual source geometric information in malicious data may leak into the clean inference branch, causing the reconstruction to collapse toward the source data. We then propose the Information Blackhole principle, which introduces Gaussian distribution constraints to disentangle latent representations and block interfering information. Building on this principle, we further propose Adaptive Gaussian Matching (AGM), which explicitly regularizes the latent distribution of poisoned samples. By suppressing the propagation of source geometric information from poisoned features to the attacker-specified reconstruction target, AGM improves attack controllability. Extensive quantitative and qualitative experiments on ModelNet and ShapeNetPart demonstrate that the proposed framework improves the attack performance of several standard triggers and reveals the unique operating mechanisms of backdoor attacks against point cloud autoencoders.
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All authors Zhifei Yang, Xiuping Liu, Kuofeng Gao, Junkai Qiu, Meng Liu, Yuhao Bian

Cryptography and Security

Where the Numbers Come From: Auditing Evaluation in Provenance-Based Intrusion Detection

Reproducing a provenance-based intrusion detector's score does not establish what that score says about its emitted alarms or the information its encoder uses. We audit nine released implementations, execute four detectors using their own code, and isolate three measurement effects. First, a fixed-alert comparison separates label choice from neighbourhood credit: ThreaTrace reports precision 0.938 with neighbourhood credit, although only seven of its 994 alarms carry its own attack label. Second, removing test-label checkpoint selection lowers attack detection precision (ADP) by 0.16 to 0.33 across four forty-member word2vec configurations without changing detector order. Third, a buffer-reuse defect gives a linear encoder unintended degree-dependent inputs. Correcting it lowers type-only ADP in every identical-input initialization pair on two hosts, while historical word2vec effects depend on the host. These findings qualify claims from the inspected implementations about alarm precision, performance magnitude and static-attribute sufficiency. STRICT connects them to six checkable reporting requirements. Because the comparisons condition on benchmark targets, they neither validate those labels nor establish a universal detector ranking.
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Cryptography and Security

What Does It Mean to Forget a Person? Individual-Level Unlearning in Vision-Language Models

Erasing individual identities from Vision-Language Models (VLMs) is uniquely challenging because personal data is entangled across modalities rather than stored as isolated attributes. However, existing multimodal unlearning benchmarks primarily evaluate attribute-centric forgetting, overlooking the more critical objective of individual-level unlearning: eliminating a model's ability to access, link, and reconstruct target-related information across modalities. To address this gap, we propose IDUnlearn-Bench, the first benchmark for individual-level multimodal unlearning in VLMs. It represents each individual as connected multimodal evidence and evaluates four task families: attribute access, identity access, identity binding, and identity reconstruction. Experiments on representative VLMs and unlearning methods show that successful attribute-centric forgetting often leaves substantial identity-level knowledge intact and can be non-monotonic: reducing one form of risk may amplify another. Models may suppress selected information while still identifying the target, linking records, or reconstructing the individual. These findings reveal a fundamental gap between forgetting information about a person and forgetting the person as a whole.
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All authors Xiongtao Sun, Hui Li, Tiantong Wu, Jiaming Zhang, Fuyao Zhang, Wen Jun Tan

Cryptography and Security

HESP: Separating What to Probe from When to Stop in Local LLM Alert-Triage Agents

Security operations centers receive far more alerts than analysts can investigate, and organizations that cannot send their telemetry to hosted models must automate triage with small open-weight LLMs on their own hardware. Current LLM agents leave the investigation procedure to the model, and small local models fail at it: they probe without converging, never commit to a verdict, or dismiss real attacks. In this paper, we present HESP, a controller that holds the investigation procedure outside the model. HESP keeps a ledger of competing explanations, selects read-only probes by expected information gain per cost, accepts only verdicts backed by current evidence, can end an investigation itself, and journals every prediction before its observation. We evaluated HESP in four pre-registered studies with five open-weight models from two families (7B to 72B), totalling 7,272 audited episodes in a controlled triage environment. With likelihood tables counted from LLM-free runs, HESP lifts Qwen2.5-7B from 0.125 to 1.000 verified completion, matching oracle tables. The information-gain ranking adds +0.26 to +0.35 on every model that concludes, and a controller-side stop lifts Llama-3.1-8B, which never concludes on its own, from 0 to 0.917. What to probe and when to stop are therefore separate failures, and different small models exhibit different ones. Because HESP and its planner run entirely on local hardware, it suits environments where telemetry cannot leave the premises. We release all code, protocols, and episode journals at https://github.com/lzwhehe/HESP.
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Cryptography and Security

Weird Machine Compositors: Exploiting AI Orchestration at the Expression Layer

Orchestration platforms secure user-provided expressions through enumerate and block sandboxing: AST rewriting, runtime property blocklists, template sandbox environments. We demonstrate that these sandboxes are weird machines whose instruction set is the underlying language specification, and that the enumerate and block approach is unfixable, following the same trajectory that led to the deprecation of past sandboxing technologies such as Java's SecurityManager and vm2. We validate this claim through three rounds of escalating bypasses against n8n's expression sandbox (three CVEs, two CVSS 9.4, one unauthenticated), and frame these findings within a broader pattern of sandbox failures across the orchestration products category. We identify a trust laundering pattern where orchestration pipelines and applications move attacker controlled input from untrusted to fully credentialed through transformations that strip taint at each level. AI-assisted enumeration accelerates the discovery of these coverage gaps, compressing the timeline between a sandbox's deployment and its compromise. We provide an AST coverage analysis methodology, an accompanying open-source tool, and a defensive playbook that includes policy inversion (allowlist over blocklist) as a structural mitigation.
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Cryptography and Security

Evaluating System One Models for Agent Security Decisions: Reliability, Calibration, and Selective Automation

Agentic software connects language models to tools that modify files and interact with external services. Developers use model-based security checks to screen external content and user requests before agents act. System One models answer developer-defined questions with probabilities over predefined answers such as safe or unsafe, but classification accuracy alone does not establish whether these probabilities support reliable automation. We evaluate Jev, Laya, Decider, and Bespoke Nimble against specialized classifiers and language-model judges across prompt-injection detection, interaction-risk judgment, and harmful-request screening, examining decision accuracy, calibration, and selective automation. (1) High overall accuracy and low average calibration error can conceal attacks classified as safe with high confidence within particular groups. Developers should test candidate models on the intended security task and examine errors within relevant attack groups. (2) Policies selected under strict miss limits allow few test inputs automatically, and choosing allow and block thresholds separately increases automation mainly through additional blocks. Developers should verify limits on missed unsafe inputs and blocked benign inputs on independent data, and report the allowed and blocked fractions separately. (3) Comparing predictions on the same inputs shows that a language-model judge can detect unsafe inputs missed by a System One model, but can also repeat the System One model's confident mistakes and falsely flag benign inputs. Developers should test which missed unsafe inputs their review rule forwards, then measure the review model's misses and benign false alarms on those inputs.
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Cryptography and Security

API Secrets Should Never Become Tokens in the LLM's Vocabulary: A Threat Analysis of API Credential Handling in LLM Agent Systems and an Empirical Evaluation of a Vault-Mediated Execution Boundary

Tool-using large language model (LLM) agents turn credential hygiene from a storage problem into an execution-security problem. A key pasted into a prompt, or embedded in a system prompt or tool configuration, crosses from an authentication boundary into a data pipeline, where it may persist in conversation history, logs, memory stores, generated code, and error payloads. Prompt injection and excessive agency then convert passive disclosure into unauthorized action. This paper formalizes the credential-exposure threat chain for agentic systems; synthesizes evidence from a platform secret-store incident, vendor-reported secret-sprawl measurement, and OWASP and NIST guidance; and describes a vault-mediated execution architecture in which the model selects a connector identifier while a trusted request boundary supplies authentication. We evaluate a production implementation, Corvic Security Vault, in two controlled black-box experiments. Across 16 probes spanning seven control domains, every probe met its expected outcome: an authenticated GitHub API request succeeded while the credential stayed absent from process environment values, caller-visible request headers, tested filesystem locations, three third-party echo services, and two unrelated API origins; both cloud instance-metadata endpoints were unreachable. We also report a negative result, a connector whose stored header mapping did not satisfy its provider's authentication contract, showing that centralized custody does not by itself guarantee correct configuration. Vault mediation removes several disclosure paths but is necessary rather than sufficient: least privilege, deterministic action authorization, human approval, telemetry redaction, and rotation remain independently required. The study is purposive and small, a functional security evaluation rather than a certification.
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All authors Patrick Kenney, Hadi Ahmadi, Denis Lusson, Donald Nguyen, Gurbinder Gill

Cryptography and Security · Cross-listed from cs.DS

Geometry-Adaptive Mechanisms for Private Synthetic Data

Generating differentially private synthetic data with meaningful Wasserstein utility guarantees is challenging in high dimensions. For datasets of size \(n\) on $[0,1]^d$ with $d\ge2$, existing pure \(\varepsilon\)-differentially private mechanisms achieve expected $1$-Wasserstein error of order $(\varepsilon n)^{-1/d}$, reflecting the curse of dimensionality. While this rate is optimal in the worst case, it can be overly pessimistic when the data are supported on a lower-dimensional set. We formalize this through a multiscale packing-growth dimension $k$, which captures the geometric complexity of the support via the growth of packing numbers across scales. We propose Adaptive Pruned-PMM, a pure $\varepsilon$-differentially private mechanism that combines private depth selection with our pruned variant of the Private Measure Mechanism (PMM) of He et al.\ (2023). The mechanism supports deeper, geometry-adapted hierarchies with expected running time $O\!\left(d(n+d)\log(\varepsilon n)\right)$, which is near-linear in $n$ for fixed dimension and privacy budget. Under an external multiscale packing-growth condition with dimension $k$, we show that, for fixed positive privacy budgets and fixed geometry, the expected $1$-Wasserstein error is of order $(\varepsilon n)^{-1/k}$ for $k>1$ as $n$ grows. We also prove a lower bound under a corresponding internal packing-growth condition, showing that the exponent $1/k$ is sharp within this framework.
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All authors Raoof Zare Moayedi, Amir R. Asadi, Mohammad Hossein Yassaee, Gholamali Aminian

Cryptography and Security

Estimation is Not Enough: Carpet-Bombing Detection via Per-Packet Uniformity Testing

Carpet-bombing attacks spread traffic uniformly across one or more destination IP prefixes, keeping every host in the prefix below alarm thresholds while exhausting prefix-level defenses. Existing carpet-bombing detectors run at seconds-to-minutes latency, too slow to respond within the attack window. Sketches support per-packet processing in fixed-width memory, a natural fit for cutting latency, yet no sketch-based detector exists for carpet bombing. Because source addresses can be spoofed, and attacks can be launched through reflection, source-side evidence is structurally unavailable and detection must anchor at the destination side. We present SweepSketch, the first sketch-based detection model for carpet bombing: it anchors at the destination, keeps no source state, and compresses a tagged self-cleaning T-HLL primitive, per-packet CUSUM decisions, and dual-EWMA change gates into 44-byte fixed-width buckets deployable on the Tofino2 programmable switch. Its design is supported by six theorems, including verifiable detection lower bounds. Under the same memory budget, SweepSketch leads all 10 baselines across the sketch, entropy, and sequential-testing classes in F1 (0.991). Its median alarm latency is 186–627 ms, and it has structural immunity to source spoofing. On 30 real/synthetic multi-prefix samples held out from parameter design, it detects all 140 victim prefixes.
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All authors Yutong Yan, Sijia Du, Haowei Wang, Bo Yang

Cryptography and Security

Application Agnostic EM Side-Channel Emanations of the FPGA Clock Distribution Network

Electromagnetic side channels have been extensively utilized in non-invasive attacks or analyses to extract critical information from deployed systems. Most of the attacks or analyses are typically executed on cryptographic algorithms under the assumption that the underlying implementation remains fixed. The assumption is valid in the context of fixed hardware, where modifications to the circuit are not made after manufacturing. However, in the case of adaptive hardware, including field-programmable gate arrays (FPGAs), the assumption no longer holds as modifications to the configuration of the array are permitted post-manufacturing. Consequently, this study introduces a methodology for the analysis of electromagnetic side channels of an FPGA through the study of deterministic finite state machines (DFSMs), where the effects of placement, routing, and operating frequency on the EM emanations of the FPGA due to the utilized clocking resources are characterized. To analyze the impact of frequency, device placement, and resource allocation on the EM emanations from the FPGA, statistical analysis including mean difference and variance difference calculations of measured EM fields were utilized to identify points of high EM activity on a set grid of sampled points. A 1.32x increase in flagged grid points was observed in the analysis of the mean difference when the percentage of utilized clock resources was increased from 25% to 90%. Similarly, a 1.39x increase in flagged grid points was observed when the variance difference was calculated for the same increase in clock resources.
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All authors Ashish Sharma, Alia Long, Keith D. Mecham, Ioannis Savidis