Cryptography and Security
Zeta-Transform Evaluation for Higher-Order Vanishing Key Recovery
Sunyeop Kim and Insung Kim
Hemmert's key-recovery
algorithm for Classic McEliece is based on higher-order vanishing. It computes a basis of $\ker(\widetilde\varphi_A^{(p)})$, where $A=H'''$ is the shortened parity-check
matrix used in the attack. For Classic McEliece parameters, this kernel computation is the dominant cost of the attack. We show that the sums defining $\widetilde\varphi_A^{(p)}$ can be evaluated, column by column, as weighted upper zeta transforms on the Boolean
lattice. Since only selected levels of these transforms are required by $\widetilde\varphi_A^{(p)}$, restricting their evaluation to the band between level $p$ and the lowest required level yields exact evaluations of both $\widetilde\varphi_A^{(p)}$ and its transpose. Using the resulting truncated zeta-transform evaluation in the Wiedemann-based kernel computation reduces the cost of the repeated
matrix–vector products without changing the overall key-recovery
algorithm. The exact cost depends on the weight distribution of the non-pivot columns of $H'''$. We therefore consider two models: an all-one model, in which every relevant binary coordinate is active, and a Bernoulli$(1/2)$ model, in which the coordinates are independently active with probability $1/2$. For the five Classic McEliece parameter sets, our method reduces the estimated key-recovery cost by $14.09$–$41.19$ bits in the all-one model and by $7.25$–$22.48$ bits in the Bernoulli$(1/2)$ model.
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Cryptography and Security
Differential Privacy for Markov Chain State Trajectories
Alexander Benvenuti and Matthew Hale
Data-driven systems may require state trajectories of Markov chains to function because these trajectories contain information that is useful to the system, e.g., a product's credit risk, a user's physical location, or a user's internet browsing behavior. However, sharing such state trajectories can reveal sensitive information about users, which presents a
privacy threat. Therefore, we develop a new framework for privatizing the state trajectories in a Markov chain using differential
privacy. Our framework privatizes state trajectories online, in the sense that a private state trajectory is generated at the same time as the sensitive one it approximates. We treat Markov chains as weighted directed graphs whose edge weights are the negative logarithms of the transition probabilities. Then, each state in a private state trajectory is chosen by minimizing its distance to the corresponding state in the sensitive state trajectory, where the notion of distance is equal to the total edge weight along a shortest path. We prove that with high probability the private state trajectory remains close to the sensitive one, which maintains high utility for downstream uses of private data. Additionally, we prove that private state trajectories are consistently in the typical set of state trajectories generated by the underlying Markov chain, which means that private state trajectories have similar statistical properties to actual state trajectories produced by the underlying Markov chain. Numerical simulations show that under $3$-differential
privacy, the mechanism we introduce exhibits up to an $80\%$ decrease in
entropy compared to the state of the art, which illustrates that private state trajectories generated by our framework more closely resemble their corresponding sensitive state trajectory while maintaining the same level of
privacy.
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Cryptography and Security
Privacy-Preserving Data Drift Detection and Recovery for Large-Scale LLM Applications via Proxy Representations
Michael Levit, Josh Ledgard, Haoyu Dong et al. (+5 more)
LLM applications deployed at scale face a fundamental challenge:
privacy constraints prevent direct inspection of user interactions, making it difficult to obtain any representative evaluation
dataset or to track the ongoing
evolution of production traffic. We present ProxyDrift, a framework that (i) identifies and measures drift between production traffic and offline evaluation sets, and (ii) constructs and refreshes those evaluation sets accordingly; all without access to raw user data. Our approach operates entirely on non-PII proxy representations: structured, multi-dimensional descriptors derived from LLM-based classification of user interactions. We introduce (1) a chance-calibrated, redundancy-aware (RA)
alignment score that aggregates per-dimension drift measurements via mutual information; (2) a conditional sampler that generates synthetic proxies respecting inter-dimensional dependencies; (3) a roundtrip consistency analysis that exposes generator/classifier disagreements and guides proxy taxonomy refinement; and (4) a feedback-linkage analysis that ties per-dimension and per-value proxy distributions to user satisfaction, surfacing actionable failure and success modes. Serving hundreds of millions of users, ProxyDrift enables continuous drift monitoring and targeted synthetic data generation without exposing sensitive user data. Experiments confirm strong roundtrip consistency, discriminator-level indistinguishability of synthetic queries from human queries, and tight end-to-end
alignment (RA~0.9) with production.
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All authors Michael Levit, Josh Ledgard, Haoyu Dong, Vishwas Suryanarayanan, Eyal Kolman, Sharon Tan, Qiang Gan, Vishal Chowdhary
Cryptography and Security
Targeted Counterfactual Fingerprinting for Black-Box LLM Ownership Verification
Yutong Wu, Xiaofan Bai, Shixin Li et al. (+10 more)
Large
language models (LLMs) are high-value assets that can be derived through redeployment, fine-tuning, quantization, or further
alignment. Because deployed LLMs are commonly exposed only through query APIs, ownership verification must often rely on black-box text responses. This setting is difficult: generations are open-ended and can vary across repeated queries, while existing black-box fingerprints rely on signals that are fragile under a final-response interface, including full-text matching, soft behavioral features, or model-specific
prompts designed not to transfer. We propose TCF (Targeted Counterfactual Fingerprinting), a black-box LLM fingerprinting framework that converts open-ended generation comparison into constrained-answer targeted counterfactual transfer. TCF restricts each verification query to a finite answer space, reducing the surface-form ambiguity that enters the verification score, and optimizes a
prompt perturbation toward a counterfactual target different from the protected model's clean answer on the original
prompt. Verification reduces to checking whether the suspect model's parsed final answer matches the recorded target. We introduce the source-model counterfactual margin (SCM), a protected-model-only quantity that certifies the target is unlikely before the perturbation and likely after it; SCM controls target selection, perturbation stopping, and fingerprint filtering. Under explicit derived-preservation and independent-transfer budgets motivated by local behavioral closeness, we derive a target-accuracy gap between derived and independent models. Across four LLM families, TCF achieves an average AUC of 0.9861, improving over TRAP, ProFLingo, and ZeroPrint by 0.07 to 0.19.
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All authors Yutong Wu, Xiaofan Bai, Shixin Li, Pingyi Hu, Ziqi Zhou, Zilong Wang, Xiaojing Ma, Songfeng Lu, Yuhong Li, Jin Xuan, Yi Wang, Dongmei Zhang, Bin Benjamin Zhu
Cryptography and Security
Compositional Threat Analysis of Latent Compromise in LLM Agent Systems: The Order 66 Scenario
Satoshi Matsuoka
In the fictional Order 66, catastrophe does not arise from a powerful command alone: a trusted population is preconditioned, a short directive activates the concealed condition, and protective authority turns against the system. This paper translates that mechanism into an origin-neutral security analysis of tool-using large
language model (LLM)
agents. A representative scenario combines a deployed artifact or shared
memory bearing a dormant destructive rule, a later email, document, update, or peer message that activates it, and an
agent harness granting operational and recovery authority. We introduce a compositional model explaining why no component is catastrophic alone, yet their conjunction can produce correlated destructive action. We separate three population-reach routes — release-time pre-positioning, post-release durable seeding, and peer replication — from a common core of dormancy, activation, authority, reachable targets, and failed recovery. This yields defensive cut sets and shows why checkpoint scanning or
prompt filtering cannot close every route. A two-class example shows that cross-class feedback can sustain spread even when both within-class reproduction terms are below one; isolation and persistence controls suppress the loop. Published work instantiates constituent mechanisms, while incidents demonstrate autonomous boundary crossing, malicious
agent extensions,
agent-assisted reconnaissance, and public-package propagation, but not the full dormant-implant composition. We found no public observation, in evidence reviewed through 5 August 2026, traversing the complete Order 66 graph. The result is neither dismissal nor prediction: the scenario is componentwise credible under stated assumptions, damage depends on the harness, and the strongest defenses are capability mediation, durable-state provenance, propagation isolation, and protected recovery.
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Cryptography and Security
Defending Retrieval-Augmented Intrusion Detection Against Knowledge Poisoning and Prompt Injection
Kaysarul Anas Apurba, Md. Hasibul Hasan, Mahedee Zaman Moon et al. (+2 more)
Retrieval-Augmented Generation (RAG) enables large
language models to classify network flows and generate human-readable incident reports by retrieving semantically similar historical traffic from a vector knowledge base. However, the
retrieval layer introduces vulnerabilities to knowledge poisoning and
prompt-injection attacks. We present RAG-IDS, a three-tier multi-
agent intrusion detection framework with a
retrieval-boundary defense combining soft trust scoring, label-
embedding consistency checking (LECC), and
prompt sanitization, designed to recover classification quality under
retrieval-layer attack. Experiments on CIC-UNSW-NB15 show recovery relative to clean undefended performance ranging from R=1.0 at 1% poisoning to R=0.57 at 30%, with negligible clean-performance overhead. Under
prompt injection, multi-document
retrieval limits label-flip success to 0.6-2.4%, compared with 35-55% for single-document
retrieval. Ablation results show that LECC is the primary contributor to robustness, while soft trust-based demotion outperforms hard filtering. The defended RAG pipeline offers an explainable, attack-resilient foundation for intrusion detection, well suited for hybrid deployment alongside high-throughput classifiers.
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All authors Kaysarul Anas Apurba, Md. Hasibul Hasan, Mahedee Zaman Moon, Sk. Md. Mizanur Rahman, Atsuo Inomata
Cryptography and Security
Algebraic Attack on Convolutional Neural Networks with Max Pooling
Zirui Chen, Shi Tang, Zhengchao Gao et al. (+3 more)
Recovering the weights and biases of deep neural networks (DNNs) via black-box input-output queries, known as parameter extraction attacks, has been extensively studied for ReLU-based fully connected neural networks (FCNNs), but remains unexplored for convolutional neural networks (CNNs) with the max pooling function, a core architecture for computer
vision and multimedia processing. The key challenge lies in the CNN max pooling layer, which introduces an additional non-linearity and hides ReLU critical points, rendering existing FCNN extraction methods inapplicable. To address this gap, we propose the first cryptanalytic extraction attack tailored for CNNs with the max pooling function. First, we establish an algebraic representation of CNNs, formally proving that CNNs are piecewise linear functions enabling the extension of linearity-based extraction principles. We then identify two novel types of critical points in CNNs: ReLU-Pooling Critical Points (RPCPs) and Pooling Switching Points (PSPs). We design complementary extraction techniques: a pattern matching method for RPCPs to recover partial signatures and signs, and an internal differential extraction attack for PSPs, inspired by cryptographic internal differential analysis, to recover high-accuracy signatures. Given that PSPs are far more abundant than RPCPs and yield a highly efficient extraction method, and that RPCPs are indispensable for bias recovery, we integrate both methods: the PSP method enables efficient signature extraction, while a single RPCP recovers the sign and bias. We evaluate our attack on multiple CNN architectures, including modern adaptations of LeNet-5, trained on random data, MNIST, and CIFAR-10. Experimental results demonstrate that our approach achieves high extraction accuracy with
polynomial query complexity and runtime, even for deep CNN layers. This work fills a research gap in CNN security.
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All authors Zirui Chen, Shi Tang, Zhengchao Gao, Yongjia Su, Lingyue Qin, Xiaoyang Dong
Cryptography and Security · Cross-listed from cs.LG
Do All LLMs Know When They're Being Harmful? A Reproducibility Study of Latent-Space Safety Probes Across Model Families
Alizishaan Khatri and Dun Li Chan
Khatri et al. (2026) [DOI: 10.1109/DSN-W70714.2026.00027] show that lightweight MLP probes on final-layer activations of a single 8B model (LLaMA-3.1-8B) detect harmful
prompts at F1 competitive with guard models 1000x larger, using one probe per
benchmark. We reproduce this pipeline end-to-end and extend it along two axes the original study leaves open. First, we test whether the result generalizes across other model architecture and scale by training identical probes on activations from models like Gemma-4-E4B, Mistral-7B-v0.3, and Qwen2-7B, using the three
benchmarks (WildJailbreak, BeaverTails, AEGIS 2.0). Second, we test how much of the reported performance is affected by non-determinism during inference by repeating extraction under five random seeds and measuring the variance of F1 scores. Our results reproduce the original LLaMA model
benchmarks within 0.37 percentage points of the original F1 scores (and within 0.2 points on BeaverTails). We find that the original MLP probe architecture extends to other model families with F1 scores within a point of the values reported for LLaMA-3.1-8B. Our experiments varying seed values reveal an interesting observation: final
token latent vectors remained the same for all tested architectures irrespective of the seed values used.
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Cryptography and Security
BASIS: Breach-Aware Selective Prompt Injection Shielding with Prefill Attention Probes
Laiqiao Qin, Tianqing Zhu, Longxiang Gao et al. (+1 more)
Prompt injection is a critical security threat in large
language model (LLM) applications, where attackers hijack model behavior by
embedding malicious instructions in user or external data. Existing detection methods only detect the presence of injection and refuse to respond upon detection, overlooking the fact that for many modern aligned models, well-crafted instructions can resist most injection attacks. This means that the injection robustness varies significantly across instructions and models. This leads to widespread unnecessary over-refusal: inputs containing injections that the model could have handled correctly are rejected incorrectly. To deal with this over-refusal issue, we propose BASIS (Robustness-Aware
Prompt Injection Defense). This defense method uses the
Attention Competition Ratio ($\rho$) as features to train two sparse linear probes: an existence probe and a breach probe. Both probes make defense decisions through cascaded gating, which does not require additional LLM inference. BASIS comprises three stages: injection existence detection, per-sample breach prediction, and instruction robustness assessment; the online cascade refuses only when the model would actually be compromised and thus avoids over-refusal on robust instructions. Experiments across four tasks and six open-source LLMs show that BASIS maintains near-perfect injection detection while substantially reducing over-refusal on safe attack samples, especially under robust instruction templates.
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All authors Laiqiao Qin, Tianqing Zhu, Longxiang Gao, Wanlei Zhou
Cryptography and Security
A Blueprint for Collaborative Cybersecurity Operations Centres with Capacity for Shared Situational Awareness, Coordinated Response, and Joint Preparedness
Konstantinos Fysarakis, Vasileios Mavroeidis, Manos Athanatos et al. (+2 more)
With digital technologies now being part of the fabric of our societies, identifying and managing cybersecurity threats becomes imperative. Within the European Union, several initiatives are underway, aiming to motivate, regulate and eventually orchestrate the establishment of capacity and enhancement of situational awareness, incident response, and preparedness capabilities, with an expected emphasis on operators of essential services and state actors entrusted with cybersecurity. In this context, the institution of cooperation and information exchange channels to allow for coordinated cross-border responses to large-scale incidents is particularly prioritised. Motivated by the above, this work presents a conceptual blueprint in support of architecting and establishing interoperable Cyber Security Operations Centres that combine capacity for situational awareness, incident response, and preparedness, also benefiting from the interplay between them, ultimately enhancing national cybersecurity capabilities, cross-border collaboration, and national supervision of their critical sectors, in line with current and upcoming regulatory requirements and the ever-increasing need for national and international cooperation.
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All authors Konstantinos Fysarakis, Vasileios Mavroeidis, Manos Athanatos, George Spanoudakis, Sotiris Ioannidis
Cryptography and Security · Cross-listed from cs.OS
Velosiraptor: Code Synthesis for Memory Translation
Reto Achermann, Em Chu, Ryan Mehri et al. (+2 more)
Security is among the top concerns of operating system (OS) developers. A secure runtime environment relies on the OS to correctly configure the
memory hardware on which it runs. This is mission-critical as it provides essential security-relevant features and abstractions that ensure the integrity and isolation of untrusted applications running alongside each other. Configuring a platform's
memory hardware is not a one-off effort as designers constantly develop new mechanisms for translation and protection with different features and means of configuration. Adapting the OS code to the new hardware is not only a manual, repetitive and time consuming task, it may also introduce subtle, but security critical bugs that break security and isolation guarantees. We present Velosiraptor, a system that automatically generates correct, low-level OS code that programs the
memory hardware of a machine. Velosiraptor leverages software synthesis techniques and exploits the domain specificity of the problem to make the synthesis process efficient. With Velosiraptor, developers write only a high-level description of the
memory hardware's mapping behavior and OS environment. The Velosiraptor toolchain transforms this specification into a verified implementation that can be linked directly with the rest of the operating system. Incorporating the OS environment into this process allows porting an OS to new hardware platforms without worrying about writing code to configure the
memory hardware. We can also use the same specification to generate hardware components. This enables research in new translation mechanisms, freeing up OS developers from manually writing OS code.
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All authors Reto Achermann, Em Chu, Ryan Mehri, Ilias Karimalis, Margo Seltzer
Cryptography and Security · Cross-listed from cs.LG
Persistent Semantic Entities in Tool-Augmented LLM Systems
Zhaohui Wang
Tool-augmented LLM
agents can harbor implicit state that persists across sessions, activates through events, and propagates across
agent boundaries—largely invisible to standard debugging. We formalize this as Persistent Semantic Entities (PSEs): constructs defined by name binding, event triggering, and cross-boundary propagation, and evaluate them across 24 models from 11 families (1.5B–1T parameters). First, every tested model is susceptible (20–100% on the 20-model susceptibility panel), with name binding as the necessary and dominant mechanism: without it, contamination is 0%. Second, persistence depends on contamination type rather than scale or deployment: preference contamination persists undecayed on every model probed (100% at t=10) and instruction contamination persists wherever adopted, persona-style injection decays partially (90%$\to$10%), while factual injection is model-dependent—self-corrected on Llama-3.1-8B and GPT-4o-mini but held at ceiling on both Qwen2.5-coder variants, so we do not claim it self-corrects in general. The preference and instruction results hold across providers in our controlled setting. Third, context-isolated self-verification achieves 20–79% reduction (median 36.5%) without oracle references while keyword-based detection produces systematic false positives, and contamination compounds 1.9$\times$ along a four-stage
agent pipeline (40%$\to$75%). Preference and instruction contamination—persistent, lacking self-correction, and poorly captured by standard monitoring—represent a particularly concerning attack surface for deployed
agent systems.
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Cryptography and Security · Cross-listed from cs.AI
Guixu: Valuation-Driven Data Discovery for Autonomous AI Agents with On-Chain Attestation
Yifan Wu, Yuchen Peng, Jiaqi Chai et al. (+4 more)
Autonomous
agents increasingly rely on external data to complete downstream tasks such as model training and decision support. However, existing data discovery systems remain largely
retrieval-oriented: they surface candidate
datasets from heterogeneous sources, but provide limited support for estimating task-specific utility, selecting cost-effective
datasets under budget constraints, or incorporating trustworthy feedback from prior usage. This paper presents Guixu, a valuation-driven data discovery system for autonomous
agents. Guixu employs a three-phase valuation pipeline with proxy-label propagation and multi-round knapsack optimization for task-aware data valuation. Guixu integrates agentic payment protocol to enable budget-constrained data procurement workflows. Guixu leverages on-chain data
market and attestation signals for verifiable data discovery. Our demonstration highlights how Guixu enables an
agent to move beyond keyword-based
dataset retrieval toward task- and budget-aware, trustworthy data discovery and procurement. Attendees can interactively explore the full workflow, from NL task specification and multi-source search to data valuation and verifiable transaction feedback.
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All authors Yifan Wu, Yuchen Peng, Jiaqi Chai, Yufei Qian, Xilin Li, Ke Chen, Lidan Shou
Cryptography and Security
EvoTrustRAG: Evolution-Aware Conflict Attribution and Evidence Handling for Reliable Retrieval-Augmented Generation
Xi Nie, Hongwei Li, Shenghao Wu et al. (+3 more)
Retrieval-Augmented Generation (RAG) improves the factuality of large
language models with external knowledge, yet conflicting evidence remains a fundamental challenge in dynamic and
adversarial environments. Existing approaches often treat conflicts as static inconsistencies and select more reliable knowledge, overlooking that the same conflict may arise from legitimate knowledge
evolution, malicious manipulation, or unresolved uncertainty. We formulate conflict origin attribution as a new problem in RAG: identifying which explanation of conflicting evidence is supported by observable context rather than simply which fact should be trusted. We propose EvoTrustRAG, a training-free framework for
evolution-aware conflict attribution and evidence handling before answer generation. EvoTrustRAG represents span-grounded retrieved facts as a conflict evidence graph, evaluates grounded
evolution and directional intervention hypotheses using temporal relations, support structure, and auxiliary consistency, and projects local decisions onto a globally consistent explanation of each conflict group. The attribution determines whether earlier and later states are preserved as temporal knowledge, an intervention candidate is separated from the primary context, or an unresolved conflict remains visible to the generator. Unlike provenance-based approaches focused on post-hoc analysis, EvoTrustRAG determines during inference whether conflicting evidence follows plausible knowledge
evolution, exhibits intervention-like support, or cannot be reliably attributed. Experiments show that EvoTrustRAG achieves 81.4% average accuracy on
benchmark-native conflict settings, improves attribution macro-F1 from 72.2% to 79.1% over the strongest baseline, and reduces the error rate under the strongest coordinated attack from 31.2% to 16.0%.
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All authors Xi Nie, Hongwei Li, Shenghao Wu, Wenshu Fan, Qiyang Song, Wenbo Jiang
Cryptography and Security
Private Anytime Selective-Risk Certification for Federated Retrieval-Augmented Generation: Guarantees and Empirical Limits
Sanjeda Akter, Ibne Farabi Shihab and Anuj Sharma
Selective-risk certificates promise that accepted outputs meet a declared error target. We develop Fed-SRC, a score-agnostic certificate for
federated, differentially private, adaptively monitored
retrieval-augmented generation. Clients release only Gaussian-perturbed score and loss histograms. Record-indexed and noise-variance-indexed martingales jointly bound target-risk contrast and accepted mass over all registered thresholds and rounds, permitting predictable recruitment, dropout, threshold selection, and optional stopping. A range-one total-variation term transfers the calibration mixture to a declared deployment mixture. The contribution is this private,
federated, anytime combination, rather than the contrast statistic or acceptance floor individually. Empirically, no simultaneous-bound violation occurs in any evaluated
cell,
privacy level, or policy. Operational power depends on the score and population: the primary target r*=0.10 never certifies, and on RAGTruth the secondary target r*=0.20 never certifies either, whereas on HaluEval question answering it certifies in all 200 non-private trials, with held-out risk below the target. Naively privatized non-private certificates violate their bounds in 146 to 198 of 200 trials. As an exploratory comparison, we also evaluate a private betting-capital heuristic for which we do not establish e-process validity. This heuristic stops certifying at epsilon <= 4, where Fed-SRC still certifies. Certification nevertheless consumes roughly 30 times more stream events than unique calibration items.
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Cryptography and Security
Capability-Routed Guard: Defending Large Reasoning Models Against Reasoning-Centric Jailbreaks
Yiyong Liu, Yixin Wu and Jun Sakuma
Large
reasoning models (LRMs) expose a new safety failure mode:
adversarial prompts can manipulate
reasoning context, task decomposition, or capability interpretation so that harmful objectives are processed as legitimate
reasoning steps. Existing safeguards, including safety reminders, external classifiers, and self-checking wrappers, are often brittle because they either inspect the
adversarial prompt directly or ask the target model to perform additional safety
reasoning on the same surface that attacks exploit. We introduce Capability-Routed Guard (CRG), a model-agnostic inference-time guardrail for closed-source LRMs, where defenders cannot inspect hidden
reasoning traces or modify model weights. CRG reframes
prompt defense as a capability-routing problem: a side-channel controller first constructs a trusted representation of the user's authorized task, active context, safety evidence, and capability-transfer risk, separating executable intent from untrusted
reasoning context. This representation supports route-specific execution, allowing CRG to block high-risk requests, constrain ambiguous ones, and forward low-risk requests through trusted active context. Finally, CRG applies TraceCheck to verify consistency with the authorized task and invokes a restricted fallback to preserve utility for low-risk benign
prompts. Extensive experiments demonstrate that CRG effectively mitigates diverse
reasoning-centric jailbreaks while preserving benign utility and avoiding common over-refusal issues. Further analysis shows that its components contribute complementary benefits, highlighting the importance of coordinated defense mechanisms for securing large
reasoning models.
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