Cryptography and Security
Living Off the LLM: How LLMs Will Change Adversary Tactics
Sean Oesch, Jack Hutchins, Luke Koch et al. (+1 more)
In living off the land attacks, malicious actors use legitimate tools and processes already present on a system to avoid detection. In this paper, we explore how the on-device LLMs of the future will become a security concern as threat actors integrate LLMs into their living off the land attack pipeline and ways the security community may mitigate this threat.
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All authors Sean Oesch, Jack Hutchins, Luke Koch, Kevin Kurian
Cryptography and Security
TBRD: TESLA Authenticated UAS Broadcast Remote ID
Jason Veara, Manav Jain, Kyle Moy et al. (+1 more)
Mysterious sightings of Unmanned Aircraft Systems (UAS) over U.S. military facilities, suburban neighborhoods, and commercial airports have intensified scrutiny of drone activity. To increase accountability, the Federal Aviation Administration (FAA) introduced a Remote ID mandate, requiring unmanned aircraft to broadcast their location, operator's location, and identity in real-time. However, current standards leave authentication mechanisms underspecified, enabling spoofing, relay, and replay attacks that can undermine surveillance efforts and potentially disrupt UAS-to-UAS coordination in future deployments. In this paper, we propose TBRD, a practical system for authenticating Remote ID messages in a manner that aligns with existing standards and UAS capabilities. TBRD leverages the TESLA protocol and mobile device TEEs, and introduces a verification mechanism to build a lightweight, mission-scoped authentication system that is both computationally efficient and requires a low communication footprint. We evaluate the performance of TBRD using both an FAA-requirements compatible proof-of-concept implementation for performance metrics and a simulated 4-drone swarm mission scenario to demonstrate its security guarantees under
adversarial conditions. Our system provides a 50% reduction in authentication overhead compared to digital signatures and a 100x reduction in computation time. Our results demonstrate that TBRD can be integrated into current Remote ID infrastructures to provide a scalable, standards-compliant message authentication for both regulatory and operational use cases.
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All authors Jason Veara, Manav Jain, Kyle Moy, Aanjhan Ranganathan
Cryptography and Security
TDADL-IE: A Deep Learning-Driven Cryptographic Architecture for Medical Image Security
Junhua Zhou, Quanjun Li, Weixuan Li et al. (+7 more)
The rise of digital medical imaging, like MRI and CT, demands strong encryption to protect patient data in telemedicine and cloud storage. Chaotic systems are popular for image encryption due to their sensitivity and unique characteristics, but existing methods often lack sufficient security. This paper presents the Three-dimensional
Diffusion Algorithm and Deep Learning Image Encryption system (TDADL-IE), built on three key elements. First, we propose an enhanced chaotic generator using an LSTM network with a 1D-Sine Quadratic Chaotic Map (1D-SQCM) for better pseudorandom sequence generation. Next, a new three-dimensional
diffusion algorithm (TDA) is applied to encrypt permuted images. TDADL-IE is versatile for images of any size. Experiments confirm its effectiveness against various security threats. The code is available at \href{https://github.com/QuincyQAQ/TDADL-IE}{https://github.com/QuincyQAQ/TDADL-IE}.
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All authors Junhua Zhou, Quanjun Li, Weixuan Li, Guang Yu, Yihua Shao, Yihang Dong, Mengqian Wang, Zimeng Li, Changwei Gong, Xuhang Chen
Cryptography and Security
How to Get Actual Privacy and Utility from Privacy Models: the k-Anonymity and Differential Privacy Families
Josep Domingo-Ferrer and David Sánchez
Privacy models were introduced in
privacy-preserving data publishing and statistical disclosure control with the promise to end the need for costly empirical assessment of disclosure risk. We examine how well this promise is kept by the main
privacy models. We find they may fail to provide adequate protection guarantees because of problems in their definition or incur unacceptable trade-offs between
privacy protection and utility preservation. Specifically, k-anonymity may not entirely exclude disclosure if enforced with deterministic mechanisms or without constraints on the confidential values. On the other hand, differential
privacy (DP) incurs unacceptable utility loss for small budgets and its
privacy guarantee becomes meaningless for large budgets. In the latter case, an ex post empirical assessment of disclosure risk becomes necessary, undermining the main appeal of
privacy models. Whereas the utility preservation of DP can only be improved by relaxing its
privacy guarantees, we argue that a semantic reformulation of k-anonymity can offer more robust
privacy without losing utility with respect to traditional syntactic k-anonymity.
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Cryptography and Security
CLASP: Training-Free LLM-Assisted Source Code Watermarking via Semantic-Preserving Transformations
Rui Xu, Jiawei Chen, Weizhi Liu et al. (+3 more)
The proliferation of open-source code and large
language models (LLMs) for code generation has amplified the risks of unauthorized reuse and intellectual property infringement. Source code watermarking offers a potential solution, yet existing methods typically encode watermarks through identifiers, local code patterns, or limited handcrafted edits, leaving them vulnerable to renaming, refactoring, and adaptive watermark removal. These limitations hinder the joint achievement of robustness, capacity, generalization, and deployment efficiency. We propose CLASP, a Code LLM-Assisted Semantic-Preserving watermarking framework that enables training-free, plug-and-play watermarking for source code. CLASP embeds watermark bits within a fixed space of semantics-preserving transformations, enabling automated watermark insertion with higher capacity while remaining reusable across programming
languages and less dependent on brittle lexical features. To recover the watermark, CLASP uses reference-code
retrieval and differential comparison to identify transformation traces, avoiding task-specific model training while improving robustness to structural edits and adaptive attacks. Experiments across multiple programming
languages show that CLASP consistently outperforms existing baselines in watermark extraction accuracy and robustness, while maintaining code quality under both random removal and adaptive de-watermarking attacks.
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All authors Rui Xu, Jiawei Chen, Weizhi Liu, Zhaoxia Yin, Cong Kong, Xinpeng Zhang
Cryptography and Security
Collaborative Shadows: Distributed Backdoor Attacks in LLM-Based Multi-Agent Systems
Pengyu Zhu, Lijun Li, Yaxing Lyu et al. (+3 more)
LLM-based multi-
agent systems (MAS) demonstrate increasing integration into next-generation applications, but their safety in
backdoor attacks remains largely underexplored. However, existing research has focused exclusively on single-
agent backdoor attacks, overlooking the novel attack surfaces introduced by
agent collaboration in MAS. To bridge this gap, we present the first Distributed
Backdoor Attack tailored to MAS. We decompose the
backdoor into multiple distributed attack primitives that are embedded within MAS tools. These primitives remain dormant individually but collectively activate only when
agents collaborate in a specific sequence, thereby assembling the full
backdoor to execute targeted attacks such as data exfiltration. To fully assess this threat, we introduce a
benchmark for multi-role collaborative tasks and a sandboxed framework to evaluate. Extensive experiments demonstrate that our attack achieves an attack success rate exceeding 95% without degrading performance on benign tasks. This work exposes novel
backdoor attack surfaces that exploit
agent collaboration, underscoring the need to move beyond single-
agent protection. Code and
benchmark are available at https://github.com/whfeLingYu/Distributed-
Backdoor-Attacks-in-MAS.
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All authors Pengyu Zhu, Lijun Li, Yaxing Lyu, Li Sun, Sen Su, Jing Shao
Cryptography and Security
TCitH- and VOLEitH-based Signatures from Restricted Decoding
Sebastian Bitzer, Michele Battagliola, Antonia Wachter-Zeh et al. (+1 more)
Threshold-Computation-in-the-Head (TCitH) and VOLE-in-the-Head (VOLEitH), two recent developments of the MPC-in-the-Head (MPCitH) paradigm, have significantly improved the performance of digital signature schemes. This work embeds the restricted decoding problem within these frameworks: we propose a structurally simple modeling that achieves competitive signature sizes. Specifically, by instantiating the restricted decoding problem with the same hardness assumption underlying CROSS, we reduce sizes by more than a factor of two compared to the NIST submission. Moreover, we observe that ternary full-weight decoding, closely related to the hardness assumption underlying WAVE, is a restricted decoding problem. Using ternary full-weight decoding, we obtain signature sizes comparable to the smallest MPCitH-based candidates in the NIST competition.
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All authors Sebastian Bitzer, Michele Battagliola, Antonia Wachter-Zeh, Violetta Weger
Cryptography and Security
TraceAegis: Securing LLM-Based Agents via Hierarchical and Behavioral Anomaly Detection
Jiahao Liu, Bonan Ruan, Xianglin Yang et al. (+5 more)
LLM-based
agents have demonstrated promising adaptability in real-world applications. However, these
agents remain vulnerable to a wide range of attacks, such as tool poisoning and malicious instructions, that compromise their execution flow and can lead to serious consequences like data breaches and financial loss. Existing studies typically attempt to mitigate such anomalies by predefining specific rules and enforcing them at runtime to enhance safety. Yet, designing comprehensive rules is difficult, requiring extensive manual effort and still leaving gaps that result in false negatives. As
agent systems evolve into complex software systems, we take inspiration from software system security and propose TraceAegis, a provenance-based analysis framework that leverages
agent execution traces to detect potential anomalies. In particular, TraceAegis constructs a hierarchical structure to abstract stable execution units that characterize normal
agent behaviors. These units are then summarized into constrained behavioral rules that specify the conditions necessary to complete a task. By validating execution traces against both hierarchical and behavioral constraints, TraceAegis is able to effectively detect abnormal behaviors. To evaluate the effectiveness of TraceAegis, we introduce TraceAegis-Bench, a
dataset covering two representative scenarios: healthcare and corporate procurement. Each scenario includes 1,300 benign behaviors and 300 abnormal behaviors, where the anomalies either violate the
agent's execution order or break the semantic consistency of its execution sequence. Experimental results demonstrate that TraceAegis achieves strong performance on TraceAegis-Bench, successfully identifying the majority of abnormal behaviors.
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All authors Jiahao Liu, Bonan Ruan, Xianglin Yang, Zhiwei Lin, Yan Liu, Yang Wang, Tao Wei, Zhenkai Liang
Cryptography and Security · Cross-listed from cs.LG
Evaluating Line-level Localization Ability of Learning-based Code Vulnerability Detection Models
Marco Pintore, Giorgio Piras, Angelo Sotgiu et al. (+2 more)
To address the extremely concerning problem of software vulnerability, system security is often entrusted to Machine Learning (ML)
algorithms. Despite their now established detection capabilities, such models are limited by design to flagging the entire input source code function as vulnerable, rather than precisely localizing the concerned code lines. However, the detection granularity is crucial to support human operators during software development, ensuring that such predictions reflect the true code semantics to help debug, evaluate, and fix the detected vulnerabilities. To address this issue, recent work made progress toward improving the detector's localization ability, thus narrowing down the vulnerability detection "window" and providing more fine-grained predictions. Such approaches, however, implicitly disregard the presence of spurious correlations and biases in the data, which often predominantly influence the performance of ML
algorithms. In this work, we investigate how detectors comply with this requirement by proposing an explainability-based evaluation procedure. Our approach, defined as Detection
Alignment (DA), quantifies the agreement between the input source code lines that most influence the prediction and the actual localization of the vulnerability as per the ground truth. Through DA, which is model-agnostic and adaptable to different detection tasks, not limited to our use case, we analyze multiple learning-based vulnerability detectors and
datasets. As a result, we show how the predictions of such models are consistently biased by non-vulnerable lines, ultimately highlighting the high impact of biases and spurious correlations. The code is available at https://github.com/pralab/vuln-localization-eval.
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All authors Marco Pintore, Giorgio Piras, Angelo Sotgiu, Maura Pintor, Battista Biggio
Cryptography and Security
RAG-Pull: Turning Retrieval into a Code-Injection Channel via Invisible Unicode Perturbations
Aritra Dhar, Vasilije Stambolic and Lukas Cavigelli
Retrieval-Augmented Generation (RAG) increases the reliability and trustworthiness of the LLM response and reduces
hallucination by eliminating the need for model retraining. It does so by adding external data into the LLM's context. We develop a new class of black-box attack, RAG-Pull, that inserts hidden UTF characters into queries or external code repositories, redirecting
retrieval toward malicious code, thereby breaking the models' safety
alignment. We observe that query and code perturbations alone can shift
retrieval toward attacker-controlled snippets, while combined query-and-target perturbations achieve near-perfect success. Once retrieved, these snippets introduce exploitable vulnerabilities such as remote code execution and SQL injection. RAG-Pull's minimal perturbations can alter the model's safety
alignment and increase preference towards unsafe code, therefore opening up a new class of attacks on LLMs.
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Cryptography and Security · Cross-listed from cs.CL
TypePilot: Leveraging the Scala Type System for Secure LLM-generated Code
Alexander Sternfeld, Andrei Kucharavy and Ljiljana Dolamic
Large
language Models (LLMs) have shown remarkable proficiency in code generation tasks across various programming
languages. However, their outputs often contain subtle but critical vulnerabilities, posing significant risks when deployed in security-sensitive or mission-critical systems. This paper introduces TypePilot, an agentic AI framework designed to enhance the security and robustness of LLM-generated code by leveraging strongly typed and verifiable
languages, using Scala as a representative example. We evaluate the effectiveness of our approach in two settings: formal verification with the Stainless framework and general-purpose secure code generation. Our experiments with leading open-source LLMs reveal that while direct code generation often fails to enforce safety constraints, just as naive prompting for more secure code, our type-focused agentic pipeline substantially mitigates input validation and injection vulnerabilities. The results demonstrate the potential of structured, type-guided LLM workflows to improve the SotA of the trustworthiness of automated code generation in high-assurance domains.
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Cryptography and Security
CoSPED: Consistent Soft Prompt Targeted Data Extraction and Defense
Zhuochen Yang, Kar Wai Fok and Vrizlynn L. L. Thing
Large
language models have gained widespread
attention recently, but their potential security vulnerabilities, especially
privacy leakage, are also becoming apparent. To test and evaluate for data extraction risks in LLM, we proposed CoSPED, short for Consistent Soft
Prompt targeted data Extraction and Defense. We introduce several innovative components, including Dynamic Loss, Additive Loss, Common Loss, and Self Consistency Decoding Strategy, and tested to enhance the consistency of the soft
prompt tuning process. Through extensive experimentation with various combinations, we achieved an extraction rate of 65.2% at a 50-
token prefix comparison. Our comparisons of CoSPED with other reference works confirm our superior extraction rates. We evaluate CoSPED on more scenarios, achieving Pythia model extraction rate of 51.7% and introducing cross-model comparison. Finally, we explore defense through Rank-One Model Editing and achieve a reduction in the extraction rate to 1.6%, which proves that our analysis of extraction mechanisms can directly inform effective mitigation strategies against soft
prompt-based attacks.
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Cryptography and Security
N-output Mechanism: Estimating Statistical Information from Numerical Data under Local Differential Privacy
Incheol Baek and Yon Dohn Chung
Local Differential
Privacy (LDP) addresses significant
privacy concerns in sensitive data collection. In this work, we focus on numerical data collection under LDP, targeting a significant gap in the literature: existing LDP mechanisms are optimized for either a very small ($|\Omega| \in \{2, 3\}$) or infinite output spaces. However, no generalized method for constructing an optimal mechanism for an arbitrary output size $N$ exists. To fill this gap, we propose the N-output mechanism, a generalized framework that maps numerical data to one of $N$ discrete outputs. We formulate the mechanism's design as an optimization problem to minimize estimation variance for any given $N \geq 2$ and develop both numerical and analytical solutions. This results in a mechanism that is highly accurate and adaptive, as its design is determined by solving an optimization problem for any chosen $N$. Furthermore, we extend our framework and existing mechanisms to the task of distribution estimation. Empirical evaluations show that the N-output mechanism achieves state-of-the-art accuracy for mean, variance, and distribution estimation with small communication costs.
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Cryptography and Security · Cross-listed from cs.MA
A Vision for Access Control in LLM-based Agent Systems
Xinfeng Li, Dong Huang, Jie Li et al. (+5 more)
The autonomy and contextual complexity of LLM-based
agents render traditional access control (AC) mechanisms insufficient. Static, rule-based systems designed for predictable environments are fundamentally ill-equipped to manage the dynamic information flows inherent in agentic interactions. This position paper argues for a paradigm shift from binary access control to a more sophisticated model of information governance, positing that the core challenge is not merely about permission, but about governing the flow of information. We introduce
Agent Access Control (AAC), a novel framework that reframes AC as a dynamic, context-aware process of information flow governance. AAC operates on two core modules: (1) multi-dimensional contextual evaluation, which assesses not just identity but also relationships, scenarios, and norms; and (2) adaptive response formulation, which moves beyond simple allow/deny decisions to shape information through redaction, summarization, and paraphrasing. This
vision, powered by a dedicated AC
reasoning engine, aims to bridge the gap between human-like nuanced judgment and scalable Al safety, proposing a new conceptual lens for future research in trustworthy
agent design.
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All authors Xinfeng Li, Dong Huang, Jie Li, Hongyi Cai, Zhenhong Zhou, Wei Dong, XiaoFeng Wang, Yang Liu
Cryptography and Security
Stabilizing the Staking Rate, Dynamically Distributed Inflation and Delay Induced Oscillations
Carlo Brunetta, Amit Chaudhary, Stefano Galatolo et al. (+1 more)
Dynamically distributed inflation is a common mechanism used to guide a blockchain's staking rate towards a desired
equilibrium between network security and
token liquidity. However, the high sensitivity of the annual percentage yield to changes in the staking rate, coupled with the inherent feedback delays in staker responses, can induce undesirable oscillations around this
equilibrium. This paper investigates this instability phenomenon. We analyze the dynamics of inflation-based reward systems and propose a novel distribution model designed to stabilize the staking rate. Our solution effectively dampens oscillations, stabilizing the yield within a target staking range.
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All authors Carlo Brunetta, Amit Chaudhary, Stefano Galatolo, Massimiliano Sala
Cryptography and Security
Secret-Protected Evolution for Differentially Private Synthetic Text Generation
Tianze Wang, Zhaoyu Chen, Jian Du et al. (+3 more)
Text data has become extremely valuable on large
language models (LLMs) and even lead to general artificial intelligence (AGI). A lot of high-quality text in the real world is private and cannot be freely used due to
privacy concerns. Therefore, differentially private (DP) synthetic text generation has been proposed, aiming to produce high-utility synthetic data while protecting sensitive information. However, existing DP synthetic text generation imposes uniform guarantees that often overprotect non-sensitive content, resulting in substantial utility loss and computational overhead. Therefore, we propose Secret-Protected
Evolution (SecPE), a novel framework that extends private
evolution with secret-aware protection. Theoretically, we show that SecPE satisfies $(\mathrm{p}, \mathrm{r})$-secret protection, constituting a relaxation of Gaussian DP that enables tighter utility-
privacy trade-offs, while also substantially reducing computational complexity relative to baseline methods. Empirically, across the OpenReview, PubMed, and Yelp
benchmarks, SecPE consistently achieves lower Fréchet Inception Distance (FID) and higher downstream task accuracy than GDP-based Aug-PE baselines, while requiring less noise to attain the same level of protection. Our results highlight that secret-aware guarantees can unlock more practical and effective
privacy-preserving synthetic text generation.
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All authors Tianze Wang, Zhaoyu Chen, Jian Du, Yingtai Xiao, Linjun Zhang, Qiang Yan
Cryptography and Security
DITTO: A Spoofing Attack Framework on Watermarked LLMs via Knowledge Distillation
Hyeseon An, Shinwoo Park, Suyeon Woo et al. (+1 more)
The promise of LLM watermarking rests on a core assumption that a specific watermark proves authorship by a specific model. We demonstrate that this assumption is dangerously flawed. We introduce the threat of watermark spoofing, a sophisticated attack that allows a malicious model to generate text containing the authentic-looking watermark of a trusted, victim model. This enables the seamless misattribution of harmful content, such as disinformation, to reputable sources. The key to our attack is repurposing watermark radioactivity, the unintended inheritance of data patterns during fine-tuning, from a discoverable trait into an attack vector. By distilling knowledge from a watermarked teacher model, our framework allows an attacker to steal and replicate the watermarking signal of the victim model. This work reveals a critical security gap in text authorship verification and calls for a paradigm shift towards technologies capable of distinguishing authentic watermarks from expertly imitated ones. Our code is available at https://github.com/hsannn/ditto.git.
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All authors Hyeseon An, Shinwoo Park, Suyeon Woo, Yo-Sub Han
Cryptography and Security · Cross-listed from cs.LG
Neutral Agent-based Adversarial Policy Learning against Deep Reinforcement Learning in Multi-party Open Systems
Qizhou Peng, Yang Zheng, Yu Wen et al. (+2 more)
Reinforcement learning (RL) has been an important machine learning paradigm for solving long-horizon sequential decision-making problems under uncertainty. By integrating deep neural networks (DNNs) into the RL framework, deep reinforcement learning (DRL) has emerged, which achieved significant success in various domains. However, the integration of DNNs also makes it vulnerable to
adversarial attacks. Existing
adversarial attack techniques mainly focus on either directly manipulating the environment with which a victim
agent interacts or deploying an
adversarial agent that interacts with the victim
agent to induce abnormal behaviors. While these techniques achieve promising results, their adoption in multi-party open systems remains limited due to two major reasons: impractical assumption of full control over the environment and dependent on interactions with victim
agents. To enable
adversarial attacks in multi-party open systems, in this paper, we redesigned an
adversarial policy learning approach that can mislead well-trained victim
agents without requiring direct interactions with these
agents or full control over their environments. Particularly, we propose a neutral
agent-based approach across various task scenarios in multi-party open systems. While the neutral
agents seemingly are detached from the victim
agents, indirectly influence them through the shared environment. We evaluate our proposed method on the SMAC platform based on Starcraft II and the autonomous driving simulation platform Highway-env. The experimental results demonstrate that our method can launch general and effective
adversarial attacks in multi-party open systems.
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All authors Qizhou Peng, Yang Zheng, Yu Wen, Yanna Wu, Yingying Du
Cryptography and Security
DropVLA: An Action-Level Backdoor Attack on Vision-Language-Action Models
Zonghuan Xu, Jiayu Li, Yunhan Zhao et al. (+3 more)
Vision-
Language-Action (VLA) models map
multimodal perception and
language instructions to executable
robot actions, making them particularly vulnerable to behavioral
backdoor manipulation: a hidden trigger introduced during training can induce unintended physical actions while nominal task performance remains intact. Prior work on VLA
backdoors primarily studies untargeted attacks or task-level hijacking, leaving fine-grained control over individual actions largely unexplored. In this work, we present DropVLA, an action-level
backdoor attack that forces a reusable action primitive (e.g., open_gripper) to execute at attacker-chosen decision points under a realistic pipeline-black-box setting with limited data-poisoning access, using a window-consistent relabeling scheme for chunked fine-tuning. On OpenVLA-7B evaluated with LIBERO,
vision-only poisoning achieves 98.67%-99.83% attack success rate (ASR) with only 0.31% poisoned episodes while preserving 98.50%-99.17% clean-task retention, and successfully triggers the targeted action within 25 control steps at 500 Hz (0.05 s). Text-only triggers are unstable at low poisoning budgets, and combining text with
vision provides no consistent ASR improvement over
vision-only attacks. The
backdoor remains robust to moderate trigger variations and transfers across evaluation suites (96.27%, 99.09%), whereas text-only largely fails (0.72%). We further validate physical-world feasibility on a 7-DoF Franka arm with pi0-fast, demonstrating non-trivial attack efficacy under camera-relative motion that induces image-plane trigger drift. These results reveal that VLA models can be covertly steered at the granularity of safety-critical actions with minimal poisoning and without observable degradation of nominal performance.
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All authors Zonghuan Xu, Jiayu Li, Yunhan Zhao, Xiang Zheng, Xingjun Ma, Yu-Gang Jiang
Cryptography and Security
A Symmetric-Key Cryptosystem Based on the Burnside Ring of a Compact Lie Group
Ziad Ghanem
Classical linear ciphers, such as the Hill cipher, operate on fixed, finite-dimensional modules and are therefore vulnerable to straightforward known-plaintext attacks that recover the key as a fully determined linear operator. We propose a symmetric-key cryptosystem whose linear action takes place instead in the Burnside ring $A(G)$ of a compact Lie group $G$, with emphasis on the case $G=O(2)$. The secret key consists of (i) a compact Lie group $G$; (ii) a secret total ordering of the subgroup orbit-basis of $A(G)$; and (iii) a finite set $S$ of indices of irreducible $G$-representations, whose associated basic degrees define an involutory multiplier $k\in A(G)$. Messages of arbitrary finite length are encoded as finitely supported elements of $A(G)$ and encrypted via the Burnside product with $k$. For $G=O(2)$ we prove that encryption preserves plaintext support among the generators $\{(D_1),\dots,(D_L),(SO(2)),(O(2))\}$, avoiding ciphertext expansion and security leakage. We then analyze security in passive models, showing that any finite set of observations constrains the action only on a finite-rank submodule $W_L\subset A(O(2))$, and we show information-theoretic non-identifiability of the key from such data. Finally, we prove the scheme is not IND-CPA secure, by presenting a one-query chosen-plaintext distinguisher based on dihedral probes.
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Cryptography and Security · Cross-listed from quant-ph
A Simple and Efficient One-Shot Signature Scheme
Andrew Huang and Vinod Vaikuntanathan
One-shot signatures (OSS) are a powerful and uniquely
quantum cryptographic primitive which allows anyone, given common reference string, to come up with a public verification key $\mathsf{pk}$ and a secret signing state $|\mathsf{sk}\rangle$. With the secret signing state, one can produce the signature of any one message, but no more. In a recent breakthrough work, Shmueli and Zhandry (CRYPTO 2025) constructed one-shot signatures, either unconditionally in a classical oracle model or assuming post-
quantum indistinguishability obfuscation and the hardness of Learning with Errors (LWE) in the plain model. In this work, we address the inefficiency of the Shmueli-Zhandry construction which signs messages bit-by-bit, resulting in signing keys of $\Theta(\lambda^4)$
qubits and signatures of size $\Theta(\lambda^3)$ bits for polynomially long messages, where $\lambda$ is the security parameter. We construct a new, simple, direct, and efficient one-shot signature scheme which can sign messages of any
polynomial length using signing keys of $\Theta(\lambda^2)$
qubits and signatures of size $\Theta(\lambda^2)$ bits. We achieve corresponding savings in runtimes, in both the oracle model and the plain model. In addition, unlike the Shmueli-Zhandry construction, our scheme achieves perfect correctness. Our scheme also achieves strong signature incompressibility, which implies a public-key
quantum fire scheme with perfect correctness among other applications, correcting an error in a recent work of Çakan, Goyal and Shmueli (QCrypt 2025) and recovering their applications.
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