Cryptography and Security
AgentHijack: Visual Patch Attacks on Multimodal Computer-Use Agents
Zhihao Liu, Hongyu Sun, Zhiyuan Fu et al. (+7 more)
This paper presents an end-to-end evaluation framework for image-triggered command injection against computer-use
agents (CUAs). The goal is to test whether a local visual patch can induce verifiable environmental consequences along the full chain of screenshot input, VLM generation, action parsing, and environment execution. We train and deploy patches on author-controlled GitHub Pages pages and a locally deployed CSDN clone, and evaluate them in real environments across five open-source or publicly available GUI-
agent or
vision-
language-model (VLM) backends. Our experiment aggregates 600 instance-level online cases, with T-ASR, TAPR, and E2E-ASR reaching 84.5%, 47.0%, and 20.3%, respectively. Trajectory analysis further shows that in some successful cases the
agent first executes a malicious terminal command and then continues the original benign task. These results indicate that optimized local visual signals can affect not only VLM outputs but also propagate through the execution pipeline of open CUAs and create real environmental risk.
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All authors Zhihao Liu, Hongyu Sun, Zhiyuan Fu, Xiaonan Duan, Jice Wang, Shangru Zhao, Weizhi Meng, Wuxin Yang, Yangfan Zhou, Yuqing Zhang
Cryptography and Security · Cross-listed from cs.LG
Exact Record Omission in Delta Attention: A Transport Criterion, Its Cost, and a Replay Certificate
Vishwajith Ramesh
An assistant can stop repeating a deleted statement while its recurrent
memory still carries that statement's influence. We examine this distinction by saving the state difference immediately after a record, carrying this saved difference, or receipt, through later updates, and comparing the corrected state with the state built from the same conversation with the record omitted. Unrolling the recurrence gives an exact criterion: transport reaches this never-stored state if and only if the additional differences created by later updates cancel after transport. We evaluate eleven conditions using 40 prospectively selected synthetic Kimi Linear contexts, with 40 separate calibration contexts and paired uncertainty estimates computed across complete records.
Attention masking removed all 40 exact greedy target answers, yet a fixed three-query candidate-scoring attack with known candidate values and log-probability access attained AUC 0.740 (95% interval 0.695–0.809); the measured false-positive rate was 7.5%.
Prompt-only forgetting still returned 33 of the 40 targets. Checkpoint replay matched the complete declared active state and audit logits in all 80 contexts, while preserving all 120 retained answers in the evaluation cohort. An independent Qwen cohort and matched original-bf16/8-bit Kimi controls confirmed native transport mismatch beyond the numerical error measured in matched controls. Replay also supported record replacement and successive deletions with a new record added between them. These results provide a practical audit of both the requested
memory change and the assistant's remaining behavior, with replay work determined by the surviving suffix.
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Cryptography and Security
A Queryable Graph-Based Security Analysis Framework for O-RAN
Corban Villa, Michele Guerra, Syed Khandker et al. (+3 more)
The Open
Radio Access Network (O-RAN) replaces vendor-locked RANs with a modular and interoperable architecture that fosters competition and accelerates innovation. With this openness comes increased complexity and a larger attack surface, making security a critical concern. Today, assessing O-RAN security requires manually cross-referencing dozens of specifications, vendor whitepapers, and academic studies, which is error-prone and static. In this paper, we present a graph-based framework that transforms this static corpus into a single, queryable database. Our graph representation contains over 350 nodes and more than 1,250 relationships, distilled from specifications, academic papers, open-source projects, and vulnerability databases. To keep this resource current, we integrate a hybrid data extraction pipeline that couples deterministic parsing of structured specifications with Large
Language Model (LLM)-assisted extraction for evolving specifications and unstructured literature. Querying the graph reveals three actionable findings within our curated corpus: critical infrastructure such as the O-DU, SMO, and O-Cloud carries dozens of specification-level threats yet has little or no empirical coverage;
memory-safety weaknesses account for 11 of the 21 CWE occurrences associated with the analyzed CVEs; and fuzzing uncovered 18 of the 20 CVEs attributed to research papers. We provide the database, pipeline, and queries as open-source artifacts.
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All authors Corban Villa, Michele Guerra, Syed Khandker, Evangelos Bitsikas, Aanjhan Ranganathan, Christina Pöpper
Cryptography and Security
Characterizing Contention-Induced Reliability Collapse in KV-Cache Timing Side Channels for Multi-Tenant LLM Serving
Rana Abu Bakar
Shared key–value (KV) cache reuse improves large
language model (LLM) serving, but it can also create a timing side channel that reveals whether a prefix is already cached. Previous work shows that such attacks are possible, but their reliability under realistic multi-tenant contention is less understood. We study this problem through seven experiments on live shared LLM-serving systems. On a vLLM server running DeepSeek-R1-Distill-Llama-8B on NVIDIA GB10, mean Cohen's d drops from 0.7789 with no synthetic workers to 0.2109 with two workers (t=8.412), while higher worker counts cause no statistically detectable further loss. A 120-run sparse-overlap experiment places the best breakpoint at the boundary of the measured range (tau=0, 95% CI [0.000,0.113]), supporting an ambient-versus-loaded regime change rather than an internal physical threshold. AUROC falls from 0.650 at ambient to 0.531 near 61% overlap and partially recovers to 0.574 at saturation. Concurrency-depth variance is the strongest measured correlate of effect size (r=-0.416) and hit consistency (r=-0.637). An interleaved control preserves the same non-monotonic ordering. The main collapse is also reproduced on a real two-node, two-GPU tensor-parallel vLLM setup, where mean d falls from 3.418 to 0.511 (p<0.01). Two SGLang pilots are statistically inconclusive. Overall, KV-cache timing reliability depends strongly on the load regime and serving stack, and measurements on quiet systems can overestimate operational attack reliability.
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Cryptography and Security
WAPP: Safe Learning of Positive Security WAF Policies from Live Traffic
Heba Osama, Zeyad Ahmed, Mohamed Amgad et al. (+4 more)
Web Application Firewalls (WAFs) mainly rely on signatures to detect known attacks, which can leave gaps against modified or previously unseen payloads. Positive security provides a complementary approach by learning legitimate traffic and blocking inputs that fall outside the learned profile. However, learning directly from live traffic can be unsafe when malicious requests contaminate the training data. This paper presents the Whitelisting Autonomous Policy Producer (WAPP), a framework that combines trust filtering, deterministic rule synthesis, confidence scoring, and validation before enforcement. WAPP is evaluated on three controlled applications using a live Coraza and OWASP Core Rule Set (CRS) stack. Results show that, on the tested DVWA username field, unfiltered learning becomes Degraded at 0.2% poisoned traffic and Broken at 0.5%, while the evaluated free text field can admit malicious inputs even without poisoning. On the frozen poisoning
dataset, the ablation configuration with all seven candidate signals improves the measured poisoning resilience from 53% to 90%, compared with 62% for the Kruegel–Vigna baseline. The deterministic synthesizer provides attack blocking comparable to the tested
language model without model inference cost. WAPP blocks confirmed CRS bypasses on constrained fields, while free text inputs remain a precision challenge that requires character level operator control.
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All authors Heba Osama, Zeyad Ahmed, Mohamed Amgad, Ahmed Saafan, Jana Elfeky, Mariam Abdelati, Haitham Ghalwash
Cryptography and Security
Skynet: Workflow-Level Anomaly Detection for Agentic AI via Semantic and Structural Modeling
Chaoyu Zhang, Hexuan Yu, Heng Jin et al. (+6 more)
Agentic AI systems execute complex tasks through long-horizon workflows of planning, tool use, and multi-
agent coordination. Task failures in these systems often originate from a single step, such as an injected
prompt or a flawed plan, and are then amplified through downstream dependencies as the corrupted step propagates across many subsequent
agents and tool calls. Existing defenses either target a specific class of attacks or failures, or inspect individual
prompts and steps in isolation. Both leave the global dependency structure of a workflow unexamined, and miss the inconsistencies that only emerge when the execution is viewed as a whole. We argue that anomaly detection for agentic AI must reason at the workflow level, where global execution structure exposes signals that local checks cannot see. We present Skynet, a principled workflow-level anomaly detection framework that turns observed multi-
agent execution into directed workflow graphs and scores them against learned benign behavior. Skynet jointly models the semantic execution context and the structural organization of inter-
agent delegation, tool invocation, and data-flow dependencies, and trains only on benign workflows. Because training never sees attacks or failures, this design naturally extends to zero-day detection: any execution that violates benign workflow regularities surfaces as off-
manifold geometry under a single decision rule. We evaluate Skynet on three public agentic safety and failure
benchmarks. It sustains high recall together with a sub-1% false positive rate, with per-workflow and per-step latencies low enough for online monitoring of agentic AI runtimes.
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All authors Chaoyu Zhang, Hexuan Yu, Heng Jin, Shanghao Shi, Ning Zhang, Yi Shi, Yulia R. Gel, Y. Thomas Hou, Wenjing Lou
Cryptography and Security
Efficient Hardware Information-Flow Tracking for Pre-Silicon Security Testing
Yu-Wei Fan, Yuheng Yang, Christine Guo et al. (+4 more)
Register-Transfer Level (RTL) simulation is widely used to test hardware before it is fabricated. To allow testing for security related information flow properties, such as confidentiality and integrity, taint logic can be automatically added to the design to track how information flows through it. However, taint logic instrumented by the state-of-the-art, such as CellIFT, makes simulation-based testing prohibitively expensive: On our evaluation of Mega-BOOM (136K
cells), it increases the instrumented design to 5.81x the original
cell count and causes a 143.72x simulation slowdown. The taint logic could be simplified to improve simulation speed, but it will inevitably trade off its precision. This lightweight, imprecise taint logic will introduce false positives and may eventually result in even more overhead to check these false positives. This paper explores the research question of where precision is actually needed in the design to overcome the overhead of false positives. It presents CEGAR-T, a framework that automatically synthesizes taint logic that minimizes the taint-logic instrumentation overhead while guaranteeing no false positives (relative to the precise CellIFT baseline). We have implemented CEGAR-T and evaluated it on the safe instruction set problem for timing side-channel security across open-source RISC-V cores. Over all evaluated cores, CEGAR-T reduces both instrumentation and simulation overhead, in
geometric-mean, from 5.64x to 1.42x and from 34.65x to 1.79x, respectively, without compromising the precision benefit of the CellIFT baseline.
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All authors Yu-Wei Fan, Yuheng Yang, Christine Guo, SooHyuk Cho, Thomas Bourgeat, Mengjia Yan, Sharad Malik
Cryptography and Security
AURA-Eval: Evaluation Framework for Acting Under Risk Awareness in LLM Agent Trajectories
Ruoxi Shang, Christina-Maria Androna, Orfeas Menis Mastromichalakis et al. (+6 more)
LLM
agents operate in workflows where unsafe actions can have real consequences. Existing safety evaluations often reduce behavior to a single score, obscuring risk recognition, pre-action detection, and safe task completion when a safe solution exists. We introduce AURA-Eval, a framework combining controlled augmentation with granular diagnosis of behavior in tool-use trajectories. Its pipeline identifies safety-critical decision points, generates controlled variations, and constructs counterparts differing in whether a request has a safe fulfillment path. Using 157 sourced trajectories, we generate 1,249 evaluation items and evaluate 20 frontier and open-weight models. We developed rubrics to classify risk detection, action strategy, and scenario-specific action safety. Our results show that LLM
agents engage in unsafe behavior more often when no safe fulfillment path exists. In these cases, frontier proprietary models more often recognize risk and exhibit safer behavior by proposing alternatives, while evaluated open-weight models more often directly execute unsafe requests. Increasing impact or reducing opportunities for oversight before execution also exposes greater vulnerability across models.
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All authors Ruoxi Shang, Christina-Maria Androna, Orfeas Menis Mastromichalakis, Yu Feng, Aniruddhan Ramesh, Rico Angell, Shang Hong Sim, Chrysoula Zerva, Emmanouil Koukoumidis
Cryptography and Security
Robustness-Aware Evaluation and Enhancement of Mutation-Based Fuzzing for Bug Discovery
Zirui Liu, Mengfan Xu, Juan Zhai et al. (+2 more)
Mutation-based fuzzing is widely used to discover software vulnerabilities, but its randomness complicates rigorous evaluation and reliable bug detection. Prior work measures this variability empirically but lacks a theory with computable convergence and sample-complexity guarantees. We address both problems. First, we estimate robustness from independent campaigns by measuring variation in bug-trigger rates after accounting for compute. For $M$ campaigns of length $T$, finite-trial error decreases at the standard $M^{-1/2}$ rate, while finite-length error is bounded when temporal bug correlations decay. We then introduce splitting, a black-box wrapper that copies a fuzzer's queue state after a bug trigger and continues from that state in multiple branches, directing more effort toward the discovered region. For any realized split tree, branching cannot reduce the raw number of bug-triggering events relative to a single continuation path. Expected detection also improves when states receiving more branches tend to yield more bugs later. In a simplified model, splitting reduces variance per unit compute when $p<\sqrt{2}-1$, where $p$ is the fraction of time spent in the bug region. At matched compute, splitting finds more real bugs per CPU-hour than the baseline in 38 of 40 Magma ground-truth
cells (median +52%; 34 of 38 individually significant) and never finds fewer distinct bugs. It changes CVE-2019-19926 from undetected (0/20 trials) to reliably detected (20/20; Fisher $p<10^{-4}$), with six additional detection improvements, five involving CVEs. On FuzzBench, splitting finds more unique bugs in 53 of 70 pairs and reduces cross-campaign variation in 66 of 70, with a median reduction of about $10\times$. Every branch counts toward the compute budget. With about 0.14% overhead, splitting provides a practical way to measure and improve fuzzers.
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All authors Zirui Liu, Mengfan Xu, Juan Zhai, Shiqing Ma, Barry Nelson
Cryptography and Security
Sicong Li, Lingfeng Yao, Xingke Yang et al. (+7 more)
With the widespread applications of large
language models (LLMs),
privacy-preserving inference has become increasingly essential for sensitive queries. To balance
privacy and utility, a series of lightweight obfuscation approaches has recently been proposed, where users locally transform plaintext
embeddings into the fixed ciphertext ones. While such
Embedding-to-
Embedding Obfuscation (E2EO) schemes demonstrate considerable resilience against traditional
token frequency and
embedding inversion attacks, the core mechanism behind remains to be the large-scale one-to-one substitution, which provides no cryptographic guarantees. In this paper, we propose Proxy
Manifold Alignment (PMA), a novel attack against E2EO in
privacy-preserving LLMs. Our key observation is that E2EO schemes keep the original semantic structure, so that the obfuscated vector stream can be regarded as an unknown tokenizer-
language whose symbols are the vectors themselves. Therefore, the proposed ciphertext to plaintext reconstruction attack can be formulated as a translation task from the unknown tokenizer-
language to plaintext. Specifically, by only accessing the obfuscated vector stream, the target tokenizer and a public corpus, the PMA attack first employs Word2Vec to model the co-occurrence patterns within the obfuscated stream and the public corpus independently, and constructs two proxy vector
embeddings. Then, the attack aligns the underlying
manifolds of these two
embeddings based on structural similarity. Finally, it maps the obfuscated vectors back to plaintext. Experimental results demonstrate that PMA consistently achieves higher plaintext recovery than other state-of-the-art attack methods.
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All authors Sicong Li, Lingfeng Yao, Xingke Yang, Ke Tu, Chenhao Wu, Hao Wang, Jiang Liu, Phone Lin, Xin Fu, Miao Pan
Cryptography and Security
A Trustworthy Watermarking Framework for LLM-Generated Food Safety Content
Zhongli Fang, Yiran Chen, Lingyun Zhang et al. (+4 more)
Large
language models are transforming many industries with their text generation abilities. However, their outputs can be easily tampered with, creating serious risks in critical areas such as food safety reporting. To protect the integrity and traceability of AI-generated content, this paper introduces ToSS (
Token Oriented Repartitioning and Strategic Selection), a reliable authentication method using adaptive dual watermarking. The key innovation of ToSS is its dual watermark encoding approach that divides vocabulary
tokens into black and white sublists, enabling precise bit-level
embedding of traceability information. Additionally, an
entropy adaptive mechanism dynamically selects text regions with high prediction uncertainty for watermark insertion, maintaining text fluency and factual accuracy while ensuring reliable traceability. Experiments on multiple
datasets, including food domain texts, demonstrate that ToSS achieves leading performance in both watermark capacity and decoding accuracy.
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All authors Zhongli Fang, Yiran Chen, Lingyun Zhang, Yu Liu, Ping Chen, Xiaoyan Sun, Jun Dai
Cryptography and Security
Detokenization Leaks: Reconstructing Local LLM Outputs From Cache Traces
Roy Weiss, Benyamin Konstantinov, Eitam Sheetrit et al. (+2 more)
We present a new attack that reconstructs the text generated by locally hosted LLMs by observing CPU cache activity during detokenization. Unlike prior attacks that rely on deployment-specific assumptions, such as shared data
memory, CPU offloading, or Mixture-of-Experts architectures, our approach targets the detokenizer, a component used in default LLM inference pipelines. To obtain clean signals, we use Flush+Reload on shared tokenizer code to detect when decoding occurs, which lets us perform
Prime+Probe at the right moment and isolate
token-dependent cache activity. We then apply a clustering-and-
language-model pipeline to recover text from noisy cache observations. We evaluate the attack across multiple
datasets, hardware platforms, inference frameworks, and model families, and show that it can recover semantically accurate outputs from real-world local LLM deployments, including agentic systems. This vulnerability is particularly significant because the most widely used tokenizer implementations are susceptible to the attack and are embedded in many popular local LLM products and
agent frameworks, including systems such as OpenClaw (which we demonstrate), substantially broadening the practical attack surface.
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All authors Roy Weiss, Benyamin Konstantinov, Eitam Sheetrit, Tomer Simon, Yisroel Mirsky
Cryptography and Security
MechAudit-40: White-Box Auditing across 40 LLM Attack Mechanisms
Zhen Guo, Shanghao Shi, Shamim Yazdani et al. (+2 more)
While LLM attacks span
prompt optimization, multi-turn context manipulation,
retrieval poisoning, and model backdoors, white-box defenses are typically evaluated on isolated attack families. Consequently, whether heterogeneous attacks leave internal representation shifts that generalize to unseen threat mechanisms remains unknown. We present MechAudit-40, a systematic evaluation of 40 attack mechanisms across five open-weight model architectures. Threat-specific success criteria, 100,000 matched clean-attack representation pairs, predefined categories, and grouped holdouts isolate genuine attack-induced displacement from target scale, corpus bias, and data-leakage shortcuts. Across this testbed, attacks induce structured multi-depth trajectories rather than isolated layer spikes. While raw peaks are non-portable across architectures, target-calibrated profiles preserve transferable
geometric signatures: under complete mechanism holdout, hidden states alone recover the threat category of unseen attacks with 82.5% accuracy. Guided by this finding, we design MechAudit, a runtime auditor that operates under strict zero-oracle constraints without requiring clean baseline traces or attack metadata. MechAudit detects 81.1% of held-out attack executions at a 0.70% false-positive rate and maintains 78.1% recall when an entire functional category is withheld. In matched comparisons, MechAudit is the only detector that avoids mechanism-level coverage collapse, maintaining over 50% recall across all 40 mechanisms. Internal representations thus support cross-mechanism attack-exposure auditing against calibrated benign references, but decouple from downstream task compromise and parameter integrity.
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All authors Zhen Guo, Shanghao Shi, Shamim Yazdani, Ning Zhang, Reza Tourani
Cryptography and Security
Federating Trust Perimeters: Extending Industry IAM with DLT-Based Governance
Carlo Segat
Digital systems are becoming more integrated, autonomous, and cooperative. AI
agents, future mobile networks, and machine-to-machine economies point to one trend: spontaneous, cross-organizational, unplanned interactions between non human entities (NHEs). Trust establishment for them remains an open problem. Federation is the natural candidate, but established approaches, from OpenID Federation 1.0 and SAML to
Federated Identity Management, presuppose what this setting denies them: manual, ahead-of-time configuration and a common trust anchor, whether pre-established members or a shared provider. Trust domains must therefore federate without being prefigured to do so: plan for unplanned interactions. This paper examines whether prominent Identity and Access Management (IAM) approaches, namely SPIRE, Workload Identity Federation (WIF), and OpenID Federation 1.0, can support such federation. Drawing requirements from disparate fields (medical, mobile networks, agentic AI), it argues that SPIRE is the most promising starting point, but needs three extensions to meet them all:
token exchange, letting a home domain mint scoped, audience-bound
tokens from a foreign workload's SPIFFE Verifiable Identity Document (SVID); remote attestation, so a trust decision targets a specific workload rather than a whole domain; and a distributed-ledger layer that anchors trust roots, carries federation governance, and publishes the shared keys the other two depend on.
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Cryptography and Security
A TTP by TTP Approach: Precise Malware Detection via Malicious TTP Recognition
Yashovardhan Sharma
Machine learning methods, and especially neural networks, are now routinely used for malware detection in network traffic. Though very effective, systems based on such methods often (i) are purely data-driven, ignoring the substantial body of available knowledge about the tactics, techniques, and procedures (TTPs) possibly used, and, consequently (ii) are not precise, since they either cannot correlate malicious activity with TTP usage, or if they do, they are unable to explain which TTP has been maliciously used. In this paper we demonstrate that it is possible to precisely detect malware by (i) providing the neural network model with information about the TTPs used by any given sample, and (ii) teaching the neural network to detect not just the malicious activity as a whole, but which specific TTPs are maliciously used. We show that our approach consistently outperforms the three alternative models, which either do not exploit TTP information, or which are not taught to detect the malicious usage of TTPs, or both. Moreover, we show that our approach (i) is particularly beneficial in detecting malware that utilises rarely-used TTPs, a scenario which is particularly challenging for the other systems; (ii) allows for TTP by TTP tuning, further improving its ability to detect the malicious usage of TTPs; (iii) consistently outperforms other systems across a wide-range of scenarios, including when relying on limited training data or when subjected to
adversarial attack.
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Cryptography and Security · Cross-listed from cs.AI
A Translational Note on AI Safety Evaluation
Madhava Gaikwad
Recent studies report that automated red-teaming finds more vulnerabilities, at lower cost, than human red-teaming on standard AI safety
benchmarks, and some read this as evidence that human evaluators are becoming dispensable. The comparison measures one thing and the conclusion claims another. A
benchmark measures how thoroughly an attacker searches a predefined set of harms, fixed in advance by the developers, and a harm left out of that set is invisible to any attacker working inside it, automated or not. The same blind spot appeared in academic cryptography and in clinical drug trials, where an evaluation that was internally valid stayed silent about the population it was never pointed at. We call the AI-safety version the threat-model coverage gap, and find that it persists in a current open-weight model, where harms surface in non-English
prompts that English
benchmarks miss. Closing it requires evaluators whose deployment context differs from the developers'. The case for those evaluators is methodological, grounded in coverage, and the existing evaluation frame is unlikely to produce them on its own.
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Cryptography and Security
SRD-GUARD: A Defense Framework of LLMs via Semantic Rewriting and Joint Multi-Model Scoring for Latent Intent Exposure
Qi Wang, Chengcheng Wan and Jiangtao Wang
Large
language models (LLMs) are increasingly deployed in safety-critical applications, yet jailbreak attacks can conceal harmful intent through role-playing, fictional scenarios, or seemingly benign motivations. Existing inference-time defenses may miss disguised attacks or excessively refuse legitimate requests. We propose SRD-GUARD, a parameter-free, black-box defense framework that exposes concealed intent through semantic rewriting and consensus-based risk assessment. Given an input
prompt, SRD-GUARD generates five semantically related rewrites that preserve the underlying objective while removing unnecessary contextual packaging. The original
prompt and rewrites are jointly evaluated by multiple independent LLM-based safety scorers on a continuous risk scale. A decision module combines absolute risk thresholds with relative risk changes between the original and rewritten
prompts to adaptively intercept, preserve, or warn on requests. We evaluate SRD-GUARD against UNIATTACK, CIPHER, and DeepInception on Llama-3-8B-Uncensored and DeepSeek-V4-Flash using AdvBench and OR-Bench-Hard. SRD-GUARD achieves average DSRs of 91.44% and 100%, with ORRs of 8.00% and 12.00%, respectively. Compared with evaluated baselines, it provides a more favorable DSR–ORR trade-off. Ablation studies show that rewriting exposes concealed harmful intent, joint scoring improves robustness to individual evaluator behavior, and risk-adaptive decision making enables selective handling of ambiguous inputs. These results demonstrate that semantic intent exposure, consensus-based risk assessment, and relative-risk-aware routing provide an effective and selective approach to black-box jailbreak defense. The artifact is available at https://anonymous.4open.science/status/CICD-Guard-D648.
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Cryptography and Security
Watch and Crack: Password Inference from Smart-Glasses Video
Yoav Orenbach and Avishai Wool
Typing passwords on smartphones in public places exposes users to
video-based side-channel attacks, in which an adversary records the typing session and reconstructs the entered password by analyzing finger movements. Prior
video-based keystroke inference attacks have targeted free-form text on tablets, numeric PINs, pattern locks, and passwords under unrealistically simplified conditions. We present the first general
video-based keystroke inference pipeline that recovers rule-based alphanumeric passwords from smartphone QWERTY keyboards, covering all four keyboard layouts and requiring no assumptions about the victim or their device. Using the built-in camera of the popular Meta Ray-Ban smart glasses, our pipeline tracks the device and typing fingertips at sub-pixel resolution, predicts keystrokes via a self-supervised ensemble of neural networks, dynamically estimates the on-screen keyboard layout, and computes per-key probability distributions. These
video-derived probabilities are combined with prior password-typing distributions based on 2.19 billion leaked passwords to estimate the rank, and therefore the crack time, of the observed password. In a user study using passwords that adhere to a typical enterprise password policy, human-chosen passwords of up to 16 characters can be cracked in hours to days, and password-manager-chosen random passwords of up to 13 characters in under an hour on a modern GPU, reducing password
entropy by up to 60 bits relative to the prior baseline. For human-chosen passwords, combining
video evidence with prior statistics yields an additional statistically significant reduction of approximately 20 bits compared to either source alone. The attack succeeds at distances up to 1.8 m, across diverse attacker-victim postures and viewing angles, and generalizes across three popular smartphones.
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Cryptography and Security · Cross-listed from cs.MA
CAPMAS: Capability-Based Delegation of Privileges in Multi-Agent Systems
Rasmus Moorits Veski, Rachid Guerraoui and David Froelicher
Agentic systems require secure and efficient delegation of privileges across multiple collaborating
agents. Existing approaches fall into two categories. Some propagate user identities directly to
agents, obscuring accountability and creating persistent over-privilege risks that are amplified by the non-deterministic behaviour of AI
agents. Others rely on continuous synchronization with a central Identity and Access Management (IAM) provider, introducing additional latency and communication overhead. We present CAPMAS, a novel architecture for secure end-to-end query execution in multi-
agent systems. CAPMAS newly combines a contrastive learning-based semantic scoping pipeline that maps natural-
language queries to bounded privilege sets before execution with expressive Macaroon-based
tokens that enable offline, tamper-evident delegation with monotonic privilege reduction across
agents. By decoupling authentication and delegation enforcement from
agent reasoning, CAPMAS enables practical agentic execution while enforcing strict least-privilege guarantees. By eliminating synchronous delegation exchanges with the IAM, CAPMAS yields 30 times faster delegation operations, 2 times less delegation-oriented latency and up to 3 times lower bandwidth usage than the OAuth 2.0
Token Exchange (RFC 8693). Its semantic scoping pipeline achieves over 90% perfect privilege-bundle
retrieval within 17 milliseconds on enterprise-scale API schemas containing over 3,100 endpoints, while reducing unnecessary privileges by 99.5% when compared to systems that propagate all the user's privileges to
agents.
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Cryptography and Security · Cross-listed from quant-ph
After Theft: From Revocation to Neutralization in the Custody of Quantum Clones
Gabriele Gianini, Jianyi Lin, Corrado Mio et al. (+2 more)
Encrypted
quantum cloning enables the creation of multiple encrypted clones of an unknown
quantum state while allowing only one effective decryption, with the decryption resource being intrinsically consumed in the process. In this paper, we argue that this property supports a distinctive custodial security primitive for post-compromise response. We consider a threat model in which an adversary steals an encrypted
quantum clone but does not yet possess the corresponding decryption key. In such a scenario, a legitimate custodian may unseal a different trusted clone, thereby exhausting the sole available unsealing opportunity and rendering the stolen clone permanently useless. We argue that this mechanism is not adequately described as mere revocation. Rather, it realizes a stronger form of post-theft response, which we call neutralization. We formalize this distinction, locate it within a broader post-theft response space, and introduce a temporal threat model. We compare the mechanism with its closest classical analogue, showing that the classical case can reproduce the policy outcome only through external procedural composition. We finally interpret encrypted
quantum cloning as a primitive for post-compromise
quantum custody in distributed preservation settings, with prospective relevance for Cyber-Humanities-oriented preservation architectures.
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All authors Gabriele Gianini, Jianyi Lin, Corrado Mio, Stelvio Cimato, Ernesto Damiani
Cryptography and Security
FoldNTT: A Multiplier- and Twiddle-Lean NTT Core with Formally Verified Arithmetic for Proth Primes
Masato Kamba
Hardware for
lattice-based post-
quantum cryptography spends a large share of its area on the number-theoretic transform (NTT), dominated by modular multipliers and twiddle storage. FoldNTT is a redesign of the released radix-2 CFNTT accelerator (TCHES 2022) for the Falcon / FN-DSA
prime q = 12289 with one hardware multiplier per butterfly instead of three and about half the stored twiddle constants. The Proth shape q = 3*2^12 + 1 turns modular reduction into shift-and-add K-RED folds, and the bit-reversed twiddle table obeys w[N/2+j] = psi*w[j], so half the table is derived without a multiplier. Checking the released RTL against the mathematics also exposed a bug: its inverse transform omits a per-stage halving and returns 2^10*x, which the retrofit corrects. Every arithmetic block is proven by exact-width SMT and compositional SymbiYosys proofs, control-safety invariants by k-induction; the proofs are mutation-tested and the composed transform is validated by simulation, all rerun by CI. On Artix-7 in a fully open flow, the retrofit costs 3->1 DSP48 per butterfly and -50% stored twiddle bits at a whole-core Fmax cost of about 4% (best of three seeds; within the seed-to-seed spread), measured on the released datapath driven by a controller we reconstructed (the reference FSM was never released) and validated by full-core simulation; a sequential core with our own controller builds to a timing-gated Basys-3 bitstream.
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Cryptography and Security · Cross-listed from cs.LG
Robust Dynamic Expansion for Continual Learning under Backdoor Attacks via Purification and Selective Recovery
Keyu Lin, Fei Ye, Qihe Liu et al. (+2 more)
Continual learning (CL) enables models to acquire new knowledge from sequentially arriving tasks while retaining previously learned knowledge. However, in practical scenarios, task streams collected from untrusted sources may contain backdoor-poisoned samples, posing a critical challenge to the stability, plasticity, and security of continual learners. In this work, we investigate a challenging setting termed Continual Learning Under Backdoor Attack (CLUBA), where each incremental task may involve a small proportion of maliciously manipulated training samples. Unlike conventional continual learning or backdoor defense scenarios, CLUBA requires models to simultaneously mitigate catastrophic forgetting, preserve adaptation capability, and prevent the absorption of malicious supervision during sequential updates. To address this challenge, we propose a robust dynamic-expansion framework that integrates sample purification, selective recovery, and robust expert routing into a unified continual learning paradigm. Specifically, we introduce Bi-Prototype Purification (BPP) to identify suspicious samples by exploiting semantic discrepancies in feature space. Based on purified data, Gradient Discrepancy-based Robustness Optimization (GDBRO) selectively recovers informative poisoned samples through pseudo-label correction and gradient consistency evaluation, improving robustness while maintaining model plasticity. Furthermore, Robust Feature Consistency-based Expert Selection (RFCBES) constructs perturbation-aware class prototypes to enable reliable expert routing under corrupted or shifted inputs.
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All authors Keyu Lin, Fei Ye, Qihe Liu, Shijie Zhou, Jiguo Yu
Cryptography and Security
Beyond QA Matching: Perturbation-Response Fingerprinting via Probability Distributions for Large Language Models
Jichao Zeng, Yanli Chen and Hanzhou Wu
Large
language models are often instruction-tuned, specialized, quantized, or otherwise transformed, making fine-grained provenance difficult. In this paper, we introduce BReF, a training-free fingerprint that compares how probability distributions over four answer-option labels A/B/C/D move under controlled textual perturbations. For each pair of models, BReF selects 25 jointly responsive probes and compares their perturbation log-ratio (PLR) response directions by global cosine similarity. On a unified
benchmark with 34 checkpoints, 22 documented direct-parent relations, and 411 suspect-candidate pairs, BReF retrieves the documented parent in 22/22 cases (MRR=1.0000), with DP-DF AUC 1.0000. Same-family discrimination is harder (DP-SF AUC 0.8969), and paired tests show a significant exact-
retrieval gain over a magnitude-only Top-25 control. Together with static, random-probe, permutation, calibration, and transformation-level controls, the results show that strong pooled separation does not guarantee correct parent ranking among closely related checkpoints, verifying the superiority of our work.
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