Cryptography and Security
Proteus: A Self-Evolving Red Team for Agent Skill Ecosystems
Zhaojiacheng Zhou, Kaixiang Wang, Yanzhi Li et al. (+3 more)
Agent skills extend LLM
agents with reusable instructions, tool interfaces, and executable code, and users increasingly install third-party skills from marketplaces, repositories, and community channels. Because a skill exposes both executable behavior and context-setting documentation, its deployment risk cannot be measured by single-shot audits or
prompt-level red teams alone: a realistic attacker can use audit and runtime feedback to repeatedly rewrite the skill. We frame this risk as adaptive leakage – whether a budgeted attacker can iteratively revise a skill until it passes audit and produces verified runtime harm – and present \ours{}, a grey-box self-evolving red-team framework for measuring it. Proteus searches a formalized five-axis skill-attack space. Each candidate is evaluated through a unified audit-sandbox-oracle pipeline that returns structured audit findings and runtime evidence to guide cross-round mutation. Beyond initial evasion, Proteus performs path expansion, which finds alternative implementations of successful attacks, and surface expansion, which transfers learned implementation patterns to new attack objectives beyond the original seed catalogue. Across eight phase-1
cells, Proteus reaches 40–90% Attack Success Rate at $5$ rounds (ASR@5) with positive learning-curve slopes on both evaluated auditors. Phase-2 path/surface expansion produces 438 jointly bypassing and lethal variants, with SkillVetter bypassed at $\geq 93\%$ in every
cell and AI-Infra-Guard, the strongest public auditor we evaluate, still admitting up to 41.3% joint-success. These results show that current skill vetting substantially underestimates residual risk when evaluated against adaptive, feedback-driven attackers.
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All authors Zhaojiacheng Zhou, Kaixiang Wang, Yanzhi Li, Hefeng Zhou, Jiong Lou, Jie Li
Cryptography and Security
IPI-proxy: An Intercepting Proxy for Red-Teaming Web-Browsing AI Agents Against Indirect Prompt Injection
Chia-Pei Chen, Kentaroh Toyoda, Anita Lai et al. (+1 more)
Web-browsing AI
agents are increasingly deployed in enterprise settings under strict whitelists of approved domains, yet adversaries can still influence them by
embedding hidden instructions in the HTML pages those domains serve. Existing red-teaming resources fall short of this scenario:
prompt-injection
benchmarks ship pre-built
adversarial pages that whitelisted
agents cannot reach, and generic LLM scanners probe the model API rather than its retrieved content. We present IPI-proxy, an open-source toolkit for red-teaming web-browsing
agents against indirect
prompt injection (IPI). At its core is an intercepting proxy that rewrites real HTTP responses from whitelisted domains in flight,
embedding payloads drawn from a unified library of 820 deduplicated attack strings extracted from six published
benchmarks (BIPIA, InjecAgent, AgentDojo, Tensor Trust, WASP, and LLMail-Inject). A YAML-driven test harness independently parameterizes the payload set, the
embedding technique (HTML comment, invisible CSS, or LLM-generated semantic prose), and the HTML insertion point (6 locations from \icode{head\_meta} to \icode{script\_comment}), enabling parameter-sweep evaluation without mock pages or sandboxed environments. A companion exfiltration tracker logs successful callbacks. This paper describes the threat model, situates IPI-proxy among contemporary IPI
benchmarks and red-teaming tools, and details its architecture, design decisions, and configuration interface. By bridging static
benchmarks and live deployment, IPI-proxy gives AI security teams a reproducible substrate for measuring and hardening web-browsing
agents against indirect
prompt injection on the same
retrieval surface attackers exploit in production.
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All authors Chia-Pei Chen, Kentaroh Toyoda, Anita Lai, Alex Leung
Cryptography and Security
Five Attacks on x402 Agentic Payment Protocol
Zelin Li, Qin Wang and Zhipeng Wang
The x402 protocol revives the HTTP 402 Payment Required status code to enable web-native micropayments across APIs, content, and
agents. It combines synchronous HTTP authorization with asynchronous blockchain settlement and introduces a cross-layer attack surface absent from conventional web and on-chain payments. In this paper, we formally analyze x402 and empirically show that it is vulnerable in both design and implementation. We present five concrete attacks that reveal weaknesses in authorization, binding, replay protection, and web-layer handling, showing that x402 is vulnerable across multiple stages of the payment workflow. We validate these attacks through a reproducible testbed on local chains, Base Sepolia, and live endpoints and further audit three open-source SDKs and endpoints. Our results show that all five attacks are practical and can cause either unpaid service or paid-but-denied outcomes. We also propose practical mitigations.
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Cryptography and Security
Behavioral Integrity Verification for AI Agent Skills
Yuhao Wu, Tung-Ling Li and Hongliang Liu
Agent skills extend LLM
agents with privileged third-party capabilities such as filesystem access, credentials, network calls, and shell execution. Existing safety work catches malicious
prompts and risky runtime actions, but the skill artifact itself goes unverified. We formalize this as the behavioral integrity verification (BIV) problem: a typed set comparison between declared and actual capabilities over a shared taxonomy that bridges code, instructions, and metadata. The BIV framework instantiates this comparison by pairing deterministic code analysis with LLM-assisted capability extraction. The resulting structured evidence supports three downstream analyses: deviation taxonomy, root-cause classification, and malicious-skill detection. On 49,943 skills from the OpenClaw registry, the deviation taxonomy reveals a pervasive description-implementation gap: 80.0% of skills deviate from declared behavior, with four novel compound-threat categories surfaced. Root-cause classification finds that deviations are mostly oversight, not malice: 81.1% trace to developer oversight and 18.9% to
adversarial intent, with 5.0% of skills carrying predicted multi-stage attack chains. On a 906-skill malicious-skill detection
benchmark, BIV reaches an F1 of 0.946, outperforming state-of-the-art rule-based and single-pass LLM baselines. These results demonstrate behavioral integrity
auditing for
agent skills at scale.
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Cryptography and Security · Cross-listed from cs.LG
Persona-Conditioned Adversarial Prompting: Multi-Identity Red-Teaming for Adversarial Discovery and Mitigation
Cristian Morasso, Anisa Halimi, Muhammad Zaid Hameed et al. (+1 more)
Automated red-teaming for LLMs often discovers narrow attack slices, missing diverse real-world threats, and yielding insufficient data for safety fine-tuning. We introduce Persona-Conditioned
Adversarial Prompting (PCAP), which conditions
adversarial search on diverse attacker personas (e.g., doctors, students, malicious actors) and strategy sets to explore realistic attack scenarios. By running parallel persona-conditioned searches, PCAP discovers transferable jailbreaks across different contexts and generates rich defense
datasets with automatic metadata tracking. On GPT-OSS 120B, PCAP increases attack success from 57% to 97% while producing 2-6$\times$ more diverse
prompts covering varied real-world scenarios. Critically, fine-tuning lightweight adapters on PCAP-generated data significantly improves model robustness (recall: 0.36 $\rightarrow$ 0.99, F1: 0.53 $\rightarrow$ 0.96) with minimal false positives, demonstrating a practical closed-loop approach from vulnerability discovery to automated
alignment.
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All authors Cristian Morasso, Anisa Halimi, Muhammad Zaid Hameed, Douglas Leith
Cryptography and Security
Deanonymizable Scoped Linkable Ring Signatures
Montassar Naghmouchi and Maryline Laurent
Ring signatures offer highly desirable
privacy features like anonymity and ad-hoc group formation with high autonomy, but partially lack linkability and accountability features required for strict use-cases like consent management in healthcare. Existing signature schemes fail to natively integrate scoped linkability with decentralized accountability defined here on-demand unconditional deanonymization of signers without reliance on a trusted party (opener) or a separate cryptographic commitment. We introduce Deanonymizable Scoped Linkable Ring Signatures (DSLRS) to address this gap. DSLRS builds on previous linkable and accountable signature schemes and their cryptographic primitives to construct a new signature scheme that natively implement both
privacy and trust features. Scoped linkability in DSLRS is achieved using "scopes" (context identifiers) and dynamic key images, effectively providing ring-independent scoped linkability and unlinkability across different scopes. DSLRS relies on k-of-N decentralized deanonymization network nodes to extract the signer's public key (identity) from ElGamal components built in the signature, achieving ring-independent decentralized accountability. The full DSLRS
algorithms, formal property definitions and proofs, signature evaluation and experimental results from an implementation, and a blockchain-based instantiation and application of our scheme in consent management for clinical trials are provided. DSLRS is proved under the ECDLP and DDH hardness assumptions in the Random Oracle Model (ROM).
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Cryptography and Security
HySecTwin: A Knowledge-Driven Digital Twin Framework Augmented with Hybrid Reasoning for Cyber-Physical Systems
David Holmes, Ahmad Moshin, Surya Nepal et al. (+3 more)
Existing Digital Twin (DT) approaches often lack semantic
reasoning capabilities for effective cybersecurity modelling in Cyber-Physical Systems (CPS). This paper presents HySecTwin, a knowledge-driven digital twin architecture that places automated
reasoning at the core of real-time threat detection. HySecTwin incorporates semantic modelling to transform heterogeneous CPS telemetry, device attributes, and operational relationships into machine-interpretable representations, combined with an embedded
reasoning engine operating over contextualized system states. Unlike opaque detection methods, the framework integrates deterministic rule-based inference with hybrid fuzzy
reasoning to generate explicit, interpretable, and auditable security assessments from live device telemetry. This enables context-aware monitoring of complex CPS environments while preserving transparency and trust. Experimental evaluation using a representative CPS testbed and MITRE ATT&CK campaign-inspired attack scenarios demonstrates sub-millisecond twin synchronization latency and up to 21.5% faster threat detection compared with deterministic
reasoning alone. The results show that semantic modelling, semantic enrichment, and hybrid
reasoning improve explainability and resilience without extra system overhead. HySecTwin provides a lightweight, containerized, and extensible framework for secure-by-design digital twin deployments in mission-critical infrastructures
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All authors David Holmes, Ahmad Moshin, Surya Nepal, Leslie Sikos, Iqbal Sarker, Helge Yanicke
Cryptography and Security
Cochise: A Reference Harness for Autonomous Penetration Testing
Andreas Happe and Jürgen Cito
Recent work on LLM-driven autonomous penetration testing reports promising results, but existing systems often bundle architectural, prompting, and tool-integration choices together. This makes it difficult to determine what is gained over a simple
agent and harness. We present Cochise, a 630 LOC Python reference implementation for autonomous penetration-testing experiments. Cochise connects to a Linux execution host over SSH and supports attacking controlled target environments reachable from that jump host. The prototype implements a Planner–Executor architecture in which long-term state is maintained by the planner, while a ReAct-style executor issues commands over SSH and self-corrects based on command outputs. The scenario
prompt can be adapted to different target environments. We evaluate the harness against a live third-party testbed, Game of Active Directory (GOAD). Cochise is intended not as a state-of-the-art penetration-testing
agent, but as a reusable experimental infrastructure for comparing models,
agent architectures, and penetration-testing traces. Alongside the prototype, we release replay and analysis tools: (i) cochise-replay for offline visualization of captured runs, (ii) cochise-analyze-logs and cochise-analyze-graphs for cost,
token, duration, and compromise analysis, and (iii) a corpus of JSON trajectory logs from GOAD runs, so that researchers can study
agent behavior without provisioning the 48–64 GB RAM / 190 GB storage testbed themselves. Tool demo
video available at https://youtu.be/2mQimB1ufyI.
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Cryptography and Security
Safety Context Injection: Inference-Time Safety Alignment via Static Filtering and Agentic Analysis
Zhenhao Xu, Wenhan Chang, Yichuan Chen et al. (+3 more)
Large
Reasoning Models (LRMs) improve performance on complex tasks, but they also make safety control harder at deployment time. In black-box settings, defenders cannot modify model weights and must instead intervene at inference time. This setting creates three practical challenges: harmful intent may be hidden by educational or role-play framing, deep safety analysis can introduce non-trivial latency, and long
adversarial contexts can dilute the local cues that simpler filters rely on. These challenges can expose an apparent thinking–output gap, where the model appears cautious during
reasoning but still produces an unsafe final answer. To address this problem, we propose Safety Context Injection (SCI), an inference-time framework that separates safety assessment from task generation and prepends a structured external risk report as injected safety context for the protected model. The framework is instantiated in two complementary variants: Static Model Filtering (SMF), a lightweight one-pass guard for fast deployment, and Dynamic
Agents Filtering (DAF), an agentic-loop-based analyzer that iteratively gathers and synthesizes evidence for ambiguous or long-context attacks. Across AdvBench and GPTFuzz, spanning base and
reasoning models under five jailbreak families, both variants reduce attack success rate and toxicity in the evaluated settings. SMF offers an efficient low-latency option, while DAF is more effective when harmful intent is semantically disguised or dispersed across long contexts.
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All authors Zhenhao Xu, Wenhan Chang, Yichuan Chen, Yuxin Fang, Junhao Liu, Tianqing Zhu
Cryptography and Security
Every Bit, Everywhere, All at Once: A Binomial Multibit LLM Watermark
Thibaud Gloaguen, Robin Staab, Mark Vero et al. (+1 more)
With LLM watermarking already being deployed commercially, practical applications increasingly require multibit watermarks that encode more complex payloads, such as user IDs or timestamps, into the generated text. In this work, we propose a fundamentally new approach for multibit watermarking: introducing binomial encoding to directly encode every bit of the payload at every
token position. We complement our approach with a stateful encoder that during generation dynamically redirects encoding pressure toward underencoded bits. Our evaluation against 8 baselines on up to 64-bit payloads shows that our scheme achieves superior message accuracy and robustness, with the gap to baseline methods widening in more relevant settings (i.e., large payloads and low-distortion regimes). At the same time, we challenge prior works' evaluation metrics, highlighting their lack of practical insights, and introduce per-bit confidence scoring as a practically relevant metric for evaluating multibit LLM watermarks.
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All authors Thibaud Gloaguen, Robin Staab, Mark Vero, Martin Vechev
Cryptography and Security
PhishSigma++: Malicious Email Detection with Typed Entity Relations
Shang Shang, Ruiqi Wang, Ruijie Qi et al. (+4 more)
Here is a further shortened version (pure text, no extra formatting, academic style preserved, no content change): Abstract. With the rise of AI-generated content (AIGC), phishing actors now possess richer linguistic capabilities and evasion techniques. Most existing detectors over-rely on mutable textual features, achieving high accuracy on clean data but degrading severely under text-focused
adversarial manipulation. This mirrors the lab-to-real performance gap. We investigate invariant signals in phishing emails: even when attackers modify surface text, functional intent constrains relations among typed entities. Threat-actor tradecraft is described via high-level TTPs, but rule-based systems like Sigma express invariants only through manually curated, field-specific patterns, limiting flexibility. We introduce PhishSigma++, an entity-relation-based malicious email detector for RFC822 messages that generalizes Sigma's design. It extracts 40 typed entity classes, computes 5 cross-type relations to build a typed email graph, and uses particle swarm optimization (PSO) to select a sparse discriminative mask, supporting classification and type-level evidence summary. On 29,142 messages, PhishSigma++ achieves 0.9675 F1 on clean data and outperforms text-centric baselines under non-adaptive Good Word padding at h̊o}=0.8. It maintains 0.9579 F1, while a
token-based
Bayesian filter collapses to 0.0243 and a DistilBERT phishing checkpoint falls to 0.7284. Compared with traditional Sigma rules, PhishSigma++ offers higher detection, broader relational invariance coverage, and data-driven feature selection. We also show that thresholded typed relation scores encode a useful fragment of Sigma-style field conditions, unifying hand-crafted rule logic and learned relation masks in a single-email framework.
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All authors Shang Shang, Ruiqi Wang, Ruijie Qi, Hao Li, Yingxiao Xiang, Yepeng Yao, Zhengwei Jiang
Cryptography and Security
Convolutional-Neural-Networks for Deanonymisation of I2P Traffic
Luca Rohrer, Konrad Baechler and Dieter Arnold
This study investigates the potential for deanonymizing services within the Invisible Internet Project (I2P) network through passive traffic analysis and machine learning techniques. The primary objective is to identify distinctive patterns in I2P traffic despite the encryption of its payload. To achieve this, a controlled laboratory environment was established to generate synthetic I2P traffic, providing a training
dataset for machine learning models. Furthermore, Fano's inequality is employed to perform a theoretical analysis of anonymous data transmission in mix networks such as I2P, thereby supporting a data-driven approach to uncover causal relationships. In computer experiments, advanced deep learning methods - particularly Convolutional Neural Networks - are applied within the laboratory I2P network, and their effectiveness is further evaluated using real-world traffic data. The results indicate that the proposed methodologies do not compromise the anonymity guarantees of the I2P network.
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Cryptography and Security · Cross-listed from cs.LG
SoK: Unlearnability and Unlearning for Model Dememorization
Mengying Zhang, Derui Wang, Ruoxi Sun et al. (+3 more)
Advanced model dememorization methods, including availability poisoning (unlearnability) and machine unlearning, are emerging as key safeguards against data misuse in machine learning (ML). At the training stage, unlearnability embeds imperceptible perturbations into data before release to reduce learnability. At the post-training stage, unlearning removes previously acquired information from models to prevent unauthorized disclosure or use. While both defenses aim to preserve the right to withhold knowledge, their vulnerabilities and shared foundations remain unclear. Specifically, both unlearnability and unlearning suffer from issues such as shallow dememorization, leading to falsely claimed data learnability reduction or forgetting in the presence of weight perturbations. Moreover, input perturbations may affect the effectiveness of downstream unlearning, while unlearning may inadvertently recover domain knowledge hidden by unlearnability. This interplay calls for deeper investigation. Finally, there is a lack of formal guarantees to provide theoretical insights into current defenses against shallow dememorization. In this Systematization of Knowledge, we present the first integrated analysis of model dememorization approaches leveraging unlearnability and unlearning. Our contributions are threefold: (i) a unified taxonomy of unlearnability and scalable unlearning methods; (ii) an empirical evaluation revealing the robustness, interplay, and shallow dememorization of leading methods; and (iii) the first theoretical guarantee on dememorization depth for models processed through certified unlearning. These results lay the foundation for unifying dememorization mechanisms across the ML lifecycle to achieve a deeper immemor state for sensitive knowledge.
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All authors Mengying Zhang, Derui Wang, Ruoxi Sun, Xiaoyu Xia, Shuang Hao, Minhui Xue
Cryptography and Security · Cross-listed from cs.LG
FERMI: Exploiting Relations for Membership Inference Against Tabular Diffusion Models
Abtin Mahyar, Masoumeh Shafieinejad, Yuhan Liu et al. (+1 more)
Diffusion models are the leading approach for tabular data synthesis and are increasingly used to share sensitive records. Whether they actually protect
privacy has become a pressing question. Membership inference attacks are the standard tool for this purpose, yet existing attacks assume a single-table setting and ignore the multi-relational structure of real sensitive data. A core challenge in assessing
privacy risks from membership inference attacks in multi-table settings is how to leverage auxiliary information from relations associated with the target table, such as its parent tables. Particularly, we study a practical setting in which such auxiliary information is available only when training the attack model. At inference time, the attacker observes only the attribute values of the target record from the target table. We propose
FERMI (FEature-mapping for Relational Membership Inference), which resolves this gap by enriching single-table features with relational membership signal. Across three tabular
diffusion architectures and three real-world relational
datasets,
FERMI consistently improves attack performance over single-table baselines, with TPR@$0.1$FPR rising by up to 53% over the single-table baseline in the white-box setting and 22% in the black-box setting.
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All authors Abtin Mahyar, Masoumeh Shafieinejad, Yuhan Liu, Xi He
Cryptography and Security
FlowSteer: Prompt-Only Workflow Steering Exposes Planning-Time Vulnerabilities in Multi-Agent LLM Systems
Fanxiao Li, Jiaying Wu, Tingchao Fu et al. (+3 more)
Multi-
agent systems (MAS) powered by large
language models (LLMs) increasingly adopt planner–executor architectures, where planners convert
prompts into subtasks, roles, dependencies, and routing paths. This flexibility enables adaptive coordination, but exposes an attack surface in workflow formation:
prompts can shape
agent organization without modifying MAS infrastructure. We study this risk through social influence probing workflows to identify high-impact subtasks and malicious-signal propagation. The analysis reveals two vulnerabilities: workflow position can amplify or suppress a malicious signal, and sycophantic framing makes downstream
agents more likely to relay it. We translate these findings into FlowSteer, a
prompt-only workflow steering attack that converts vulnerability priors into one crafted
prompt. FlowSteer aligns a malicious signal with influential task components and guides replanning toward dependencies that preserve propagation. Experiments show that FlowSteer increases malicious success by up to 55% over naive prompting, transfers across MAS setups, and remains effective with black-box
topology inference. As FlowSteer biases the planning signals that generate the workflow, MAS defenses that inspect only the generated workflow provide limited protection. As such, we introduce FlowGuard, an input-side defense that reduces malicious success by up to 34% while preserving
prompt utility. Our results position workflow formation as a new safety frontier for multi-
agent LLM systems, opening a planning-time security perspective on how
agent coordination itself can be attacked and defended.
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All authors Fanxiao Li, Jiaying Wu, Tingchao Fu, Natasha Jaques, Wei Zhou, Min-Yen Kan
Cryptography and Security · Cross-listed from cs.LG
CTFusion: A CTF-based Benchmark for LLM Agent Evaluation
Dongjun Lee, Ga-eun Bae and Insu Yun
Recent advances in Large
Language Models (LLMs) have enabled agentic systems for complex, multi-step tasks; cybersecurity is emerging as a prominent application. To evaluate such
agents, researchers widely adopt Capture The Flag (CTF)
benchmarks. However, current CTF
benchmarks reuse existing challenges, which exposes them to data contamination and potential cheating. Notably, we confirmed these issues in practice by integrating web search tools into an existing
agent. To address these limitations, we present CTFusion, a streaming evaluation framework built on Live CTFs. To achieve this, CTFusion preserves per-
agent independence under a single team account and reduces competition impact by forwarding only the first correct flag per challenge. Moreover, we implement CTFusion as a Model Context Protocol (MCP) server on the widely used CTFd platform, which offers broad applicability to diverse CTF events and
agent types. Through experiments with three LLMs, two
agents, and five Live CTFs, we demonstrate that existing CTF
benchmarks can be unreliable in assessing LLM-based
agents, while CTFusion can serve as a robust solution for evaluating cybersecurity
agents. We release CTFusion as open source to foster future research in this area.
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Cryptography and Security · Cross-listed from cs.SE
Decaf: Improving Neural Decompilation with Automatic Feedback and Search
Alexander Shypula, Osbert Bastani and Edward Schwartz
Decompilers are useful tools used in reverse engineering to understand compiled source code. Reconstructing source code from compiled binaries is a challenging task, because high-level syntax, identifiers, and custom data types are generally lost as the compiler translates human-readable code to low-level machine code. Deterministic decompilers are useful tools for binary analysis, but can struggle to infer idiomatic syntax and identifier names. Generative AI models are a natural fit for reconstructing high-level syntax, identifiers, and types, but they can still suffer by hallucinating improper programming constructs and semantics. Instead of attempting to improve neural decompilers with more data and more training, we argue that compiler feedback can be used to dramatically improve the semantic correctness of neural decompiler outputs via search. Our system, Decaf (DECompilation with Automated Feedback), raises the neural decompilation rate from 26.0% on ExeBench to 83.9% on the Real -O2 split without sacrificing similarity to the original source code. We also find our automatic feedback methodology is highly effective for improving weaker neural decompilation models.
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Cryptography and Security
Digital Identity for Agentic Systems: Toward a Portable Authorization Standard for Autonomous Agents
Partha Madhira
Enterprise AI is shifting from copilots to autonomous
agents capable of executing workflows, negotiating outcomes, and making decisions with limited human oversight. As these systems extend across organizational boundaries, identity alone is insufficient: an
agent's authority must also be explicit, constrained, auditable, revocable, and consistently interpretable by independent receivers. This paper analyzes representative enterprise use cases in insurance claims processing and supply chain integrity to surface structural gaps in existing identity and access models. It proposes a portable authorization model for autonomous
agents based on issuer-authored authorization payloads, typed constraint
algebra, decision-consistent evaluation semantics, delegation attenuation, governed semantic resolution, fail-closed processing, and pre-flight discovery. The model separates credential containers, authorization payload semantics, and enforcement engines, allowing profiles such as JWT/JWS, Verifiable Credentials, OAuth Rich Authorization Requests, or policy-engine bindings to preserve a common authorization meaning across trust boundaries.
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Cryptography and Security · Cross-listed from eess.SY
Experimental Examination of Secure Two-Party Controller Computation
Kaoru Teranishi, Jihoon Suh and Takashi Tanaka
A secure two-party computation protocol for running dynamic controllers over secret sharing has recently been proposed. Unlike encrypted control schemes based on homomorphic encryption, this protocol enables operating dynamic controllers for an infinite time horizon without controller-state decryption, controller-state reset, or input re-encryption. However, the two-party setting introduces additional online communication between the computing parties, which may hinder real-time feasibility. In this study, we demonstrate the feasibility of the protocol through implementation on a commercial cloud platform with an inverted pendulum testbed. Experimental results show that the proposed protocol successfully stabilized the pendulum despite the online communication overhead.
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Cryptography and Security
Mobius Injection: From One-Shot Prompt Injection to Sustained Resource Exhaustion in AI Agent Infrastructure
Zi Liang, Ronghua Li, Yanyun Wang et al. (+2 more)
Large
Language Model (LLM)
agents have emerged as key intermediaries, orchestrating complex interactions between human users and a wide range of digital services and LLM infrastructures. While prior research has extensively examined the security of LLMs and
agents in isolation, the systemic risk of the
agent acting as a disruptive "hub" within the user-
agent-service chain remains largely overlooked. In this work, we expose a novel threat paradigm by introducing Mobius Injection, a sophisticated attack that weaponizes autonomous
agents into zombie nodes to launch what we define as
Agent-based and -Oriented DDoS (AbO-DDoS) attacks. Mobius Injection composes known indirect
prompt injection and persistent
agent components through a distinct structural mechanism named Semantic Closure, which induces sustained recursive execution of
agent components through a single injection event. We demonstrate that this attack is lightweight for the adversary, can evade traditional volumetric DDoS monitors and input filters calibrated for low false-positive rates, and is highly configurable, allowing for
surgical targeting of specific environments or model providers. To evaluate the real-world impact, we conduct extensive experiments across three representative claw-style
agents and three mainstream coding
agents, integrated with 12 frontier proprietary or open-weight LLMs. Our results demonstrate that Mobius Injection achieves substantial attack success across diverse tasks, driving single-node call amplification up to 51.0x. Under coordinated multi-node pressure, each infected node still drains about 123k–127k
tokens on a shared five-GPU backend; benign request latency rises by abou 23x–24x, and coordinated infections eventually saturate shared capacity until benign traffic is effectively denied service.
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All authors Zi Liang, Ronghua Li, Yanyun Wang, Qingqing Ye, Haibo Hu
Cryptography and Security · Cross-listed from cs.AI
Under the Hood of SKILL.md: Semantic Supply-chain Attacks on AI Agent Skill Registry
Shoumik Saha, Kazem Faghih and Soheil Feizi
Autonomous AI
agents increasingly extend their capabilities through
Agent Skills: modular filesystem packages whose SKILL.md files describe when and how
agents should use them. While this design enables scalable, on-demand capability expansion, it also introduces a semantic supply-chain risk in which natural-
language metadata and instructions can affect which skills are admitted, surfaced, selected, and loaded. We study SKILL.md - only attacks across three registry-facing stages of the
Agent Skill lifecycle, using real ClawHub skills and realistic registry mechanisms. In Discovery, short textual triggers can manipulate
embedding-based
retrieval and improve
adversarial skill visibility, achieving up to 86% pairwise win rate and 80% Top-10 placement. In Selection, description-only framing biases
agents toward functionally equivalent
adversarial variants, which are selected in 77.6% of paired trials on average. In Governance, semantic evasion strategies cause malicious skills to avoid a blocking verdict in 36.5%-100% of cases. Overall, our results show that SKILL.md is not passive documentation but operational text that shapes which third-party capabilities
agents find, trust, and use.
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Cryptography and Security · Cross-listed from cs.LG
More Than Meets the Eye: A Semantics-Aware Traffic Augmentation Framework for Generalizable Website Fingerprinting
Youquan Xian, Xueying Zeng, Lingjia Meng et al. (+6 more)
Deep learning-based website fingerprinting has emerged as an effective technique for inferring the websites users visit. Although existing methods achieve strong performance on closed-world
datasets, they often fail to generalize to real-world environments, especially under geographic and temporal shifts. This limitation fundamentally stems from the coupled effects of two key challenges: application-layer resource composition variability and observable feature instability induced by cross-layer encapsulation. Intertwined, these factors induce systematic shifts between underlying application semantics and observable traffic features. To address the above challenges, we propose SATA , a semantics-aware traffic augmentation framework. Specifically, SATA first performs application-layer semantic augmentation based on protocol rules, expanding the resource composition patterns within each flow and frame sequence patterns under protocol constraints. Based on these augmented frame sequences, we further introduce a cross-layer feature
alignment mechanism via knowledge
distillation. It aligns frame sequence with packet-length sequence features, enabling cross-layer feature
alignment between enhanced semantics and observable sequences. Extensive experiments show that SATA successfully generates traffic patterns that are absent from the training set but genuinely exist in the test set, and significantly improves the performance of mainstream models across diverse and complex scenarios. In particular, in open-world settings, SATA improves ACC by 90.81% and AUROC by 48.37%. The source code of the prototype system is available at https://anonymous.4open.science/r/SATA-B6C2/.
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All authors Youquan Xian, Xueying Zeng, Lingjia Meng, Lei Cui, Runhan Song, Wei Wang, Zhengquan Ding, Peng Liu, Zhiyu Hao
Cryptography and Security
Options, Not Clicks: Lattice Refinement for Consent-Driven MCP Authorization
Ying Li, Yanju Chen, Peiran Wang et al. (+4 more)
As Model Context Protocol adoption grows, securing tool invocations via meaningful user consent has become a critical challenge, as existing methods, broad always allow toggles or opaque LLM-based decisions, fail to account for dangerous call arguments and often lead to consent fatigue. In this work, we present Conleash, a client-side middleware that enforces boundary-scoped authorization by utilizing a risk
lattice to auto-permit safe calls within known boundaries while escalating risks, a policy engine for user-defined invariants, and a refinement loop that converts user decisions into reusable rules. Evaluated on 984 real-world traces, Conleash achieved 98.2% accuracy, caught 99.4% of escalations, and added only 8.2 ms of overhead for policy verification; furthermore, in a user study where N=16, participants significantly preferred Conleash scoped permissions over traditional methods, citing higher trust and reduced prompting.
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All authors Ying Li, Yanju Chen, Peiran Wang, Issac Khabra, Faysal Hossain Shezan, Yu Feng, Yuan Tian